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Ecologists strive for laws that explain interactions between organisms. Myriad hypotheses have been fundamental in increasing our understanding of plant–herbivore interactions, including the forage maturation hypothesis (FMH). The FMH has recently been extended to include contingencies of body size and digestive system: selection for greater energy potential should be negatively correlated with body mass and selection for proximity to surface water should be greater for hindgut fermenters compared to foregut fermenters or ruminants. While these general trends hold at a broad scale, intrapopulation variability still exists. For feral species that did not coevolve within their current ecological context, variability in habitat selection among populations may be greater. Consequently, understanding habitat selection of each population is imperative to properly inform management. For the case of feral horses, Equus ferus caballus , a large-bodied hindgut fermenter, understanding how they compare in habitat selection to sympatric species is of particular interest due to habitat alteration and potential competition. Across much of their range in western North America, horses are sympatric with the smaller-bodied ruminant pronghorn, Antilocapra americana. The two species overlap in space use, but we lack information on how each species selects resources within areas of overlap. Accordingly, we compared habitat selection between these two species during the growing season to understand how each responded to predictions of the FMH and to better guide potential management actions. Horses followed FMH predictions by selecting proximity to surface water and greater forage biomass. Meanwhile, pronghorn did not follow predictions of the FMH; pronghorn selected greater forage biomass but did not select greater energy potential. Both species selected greater herbaceous cover, flatter slopes and farther distances from oil and gas well pads. Our analysis reveals a high degree of selection overlap and underscores the importance of conducting population level studies to best understand how herbivores interact with the unique environments they inhabit. • We compared habitat selection of feral horses and pronghorn in an arid shrubland. • We assessed responses to predictions of the forage maturation hypothesis (FMH). • Feral horses selected proximity to surface water, following FMH predictions. • Pronghorn did not select greater energy potential, deviating from FMH predictions. [ABSTRACT FROM AUTHOR]

The Wild Free-Roaming Horses and Burros Act of 1971 provides federal oversight and protection for feral horses (wild free-roaming; WFR horses) that inhabit designated areas on public lands in the western United States. The Bureau of Land Management (BLM) estimated in 2019 that over 80,000 free-roaming equids inhabited 29 million hectares on 177 designated herd management areas. This population estimate exceeds the designated appropriate management level of 26,785. To provide BLM managers with insights regarding the U.S. public knowledge and perceptions about the management of WFR horses in the U.S., we surveyed the public using an online survey process. We hypothesized that respondents from the western U.S. would be more knowledgeable of the ecology and management of WFR horses, because of their proximity to most of the WFR horses managed in the U.S. We stratified the U.S. into five regions, with the intent to acquire at least 400 responses from each; we met this quota in four of the five regions (n of southwest = 376). Overall, the U.S. public was unknowledgeable about the ecology of WFR horses and legal management options to control their populations. While there were some associations between region, sex, age, income, and each of our questions, the strength of these associations was very weak. Therefore, demographics may not be useful in predicting the level of knowledge of the U.S. public concerning WFR horses. Our results highlight the need for improved outreach and communication efforts regarding the issues and consequences of free-roaming equid management approaches.

Simple Summary: Hair tissue records a longer activity profile of an animal's hypothalamic–pituitary–adrenal axis, and resulting production of cortisol, compared to other matrices (e.g., blood serum, saliva, or feces). Cortisol is a key hormone involved in mobilizing stored energy reserves to assist in meeting physiological demands, but production can also be triggered by psychological stimuli or perceived demands. For horses (Equus ferus caballus), most studies investigating hair cortisol concentrations (HCC) have used domesticated individuals where nutritional requirements are fully met, social structures may not be as dynamic, or reproductive behaviors and physiological demands are inhibited. Here, we investigated HCC from 282 samples of hair collected from a population of feral horses that exist under fully natural conditions, including a self-determined social structure, at Sable Island, Nova Scotia, Canada. We found that HCC was predominantly associated with sex, age, body condition, and year effects but, also, for females, the presence or absence of a foal. Female HCC was further influenced by social factors, including harem size and the number of adult males not associated with a band (i.e., bachelors) that coexisted in their home range. In addition, we evaluated biological (e.g., hair color) and procedural factors (sample mass and hair texture) against observed HCC. Cortisol is a glucocorticoid hormone produced during activation of the hypothalamic–pituitary–adrenal axis (HPA) in response to psychological or physiological demands. High amounts of circulating cortisol can be found in individuals experiencing energetically demanding physiological events, such as pregnancy, lactation, injury, or starvation, but, also, in individuals who may have less obvious HPA activation from social situations. The feral horse population on Sable Island (Nova Scotia, Canada) provides an opportunity to look at hair cortisol concentration (HCC) as a proxy for circulating cortisol concentration to better understand physiological correlates. The horse's complex social structure also allows us to look at how the population and group structure may influence HPA activation. Hair samples (n = 282) were analyzed from 113 females and 135 males. Females with dependent offspring (foals) had higher HCC than those females without dependent offspring (p = 0.005). Horses in poor body condition were also more likely to have higher HCC (females: p < 0.001, males: p = 0.028); females had greater variation in the body condition index (BCI), which also correlated with foal production. In general, the top-ranked models describing female cortisol levels included age, BCI, presence of a foal, as well as social measures such as harem size and the number of bachelors in the vicinity. The top model describing male cortisol levels included age, BCI, and year of collection only, and the number of bachelors in the home range appeared in subsequent, though still high-ranked, models. Among the variables not of direct interest, we found some significant results relating to hair color and hair texture. Differences in HCC patterns between feral and domestically kept horses (e.g., age and sex) are likely linked to periods of resource limitations, particularly for individuals experiencing energetically demanding processes such as reproduction, illness/parasitism, or related to experiencing the full range of social and reproductive behaviors. [ABSTRACT FROM AUTHOR]

Simple Summary: Hormone concentrations derived from hair can inform us of many aspects of an individual's life, such as their reproductive status or social position. Cortisol is often associated with physiological or even psychological stress, while testosterone is strongly associated with male development and reproductive success. This study investigated cortisol and testosterone concentrations of tail hair collected from feral horses living in a naturally established social structure. We compare values of hair derived cortisol (n = 153) and testosterone (n = 48) to an individual's social position as either an Immature male (2–4 years old), physically mature but non-reproductive male (Bachelor), reproductive dominant male (Stallion), or subordinate harem-associated male (tag). Immature males had significantly lower hair cortisol concentrations than adults. Hair testosterone concentrations were significantly higher in Stallions than males in the other social positions when age is accounted for. Bachelors exhibited a positive correlation between the two hormone levels, while among Stallions the association was negative. These findings suggest that patterns in hair hormone concentrations reflect known physiological interactions between cortisol and testosterone in relation to age, dominance, and reproduction, that have been established in the literature. Steroid-hormone concentrations from non-invasively obtained biomarkers, like hair, can provide a representation of circulating hormones diffused over relatively long time periods (e.g., weeks or months). The hormone cortisol is often associated with physiological or even psychological stress, while testosterone is strongly associated with male development and reproductive success. Increasingly, studies are using hormone levels derived from hair to make inferences among both domestic animals and wildlife. For horses, all previous hair hormone analysis has been done on companion or working animals. We evaluated the levels of hair cortisol (n = 153) and testosterone (n = 48) from 136 feral horses living on Sable Island, Canada that have been part of a long-term individual-based study since 2008. This population has been undisturbed and unmanaged for over 50 years, and exhibits the natural social organization for horses, harem defense polygyny. Hair samples were collected in mid to late summer and the segment analyzed corresponds with hair grown during, and following, the peak of the reproductive season. Social position was determined based on the male's role as either a dominant breeding Stallion (Stallion), a non-breeding subordinate male (tag), adult Bachelor (5 years old or older), or Immature male (2–4 years of age). While there was no difference in hair-cortisol concentration among any class of adult males (i.e., Stallion, tag, or Bachelor), Immature males had significantly lower hair cortisol concentrations than the other groups (p = 0.001). Hair testosterone levels among the four social positions were significantly higher among Stallions (p = 0.04). Hair testosterone concentration was also significantly related to the probability of a male being either a Bachelor or Stallion and was the only variable remaining in AICc model selection (p = 0.016, AICc = 32.3, Null AICc = 38.8). While not a significant relationship, Stallions had a negative correlation between hair cortisol concentrations and testosterone (R2 = −0.20, p = 0.383), and Bachelors, conversely, had a positive association (R2 = 0.43, p = 0.246). Our observations of hormone concentrations in relation to physiological, social, or reproductive parameters in this population suggest trends that are similar to what has been established using blood or other matrices. [ABSTRACT FROM AUTHOR]

Livestock farming, which produces milk and meat, is practised by nearly all cultures. But in addition to this, grazing livestock fulfils other fundamentally important roles, one of which is the maintenance of open landscapes, which in turn provides habitat for many rare plant and animal species. Whether wild large herbivores, such as red deer (Cervus elaphus), benefit from the management of the open landscapes is unknown, and there are conflicting views on the nature of the interaction between livestock and wildlife. To investigate this question, we studied interactions in space and time between red deer and livestock in an 787 ha fenced pasture in eastern Germany. First, we used faecal pellet counts to determine whether red deer were using the fenced pasture and whether livestock were using the entire available pasture. Second, we fitted ten red deer, as well as eight Konik horses (Equus ferus caballus) and eight Heck cattle (Bos taurus) with GPS-collars. These data allowed us to perform analyses of space–time interactions. The faecal pellet data showed that red deer did indeed use the fenced pasture and that livestock used the entire extent of the pasture. Further, we verified a neutral space–time interaction between red deer and livestock within the pasture. Thus, there was no indication of a negative effect of the presence of livestock on red deer inside the pasture. For these reasons, we recommend that low-intensity grazing by cattle and horses can maintain open landscapes without detrimental effects on the use of the area by red deer. [ABSTRACT FROM AUTHOR]

Simple Summary: The mammalian body plan is like a 'blueprint' that supports the survival and procreation of a species. This plan includes specialized bony structures for muscle attachment such as the ventral process of C6, a two-part bony projection divided into cranial and caudal ventral tubercles (CVT). In modern horses, muscles such as the longus colli attach to the ventral process of C6 and aid in the flexion, stabilization, fixation, and force redirection of cervical vertebrae. Recent studies identified an anomalous variation where the CVT was either unilaterally or bilaterally absent. Therefore, the purpose of this study is to determine if anomalous variations of the CVTs, as described in modern horses, is a post-domestication congenital abnormality or a normal presentation throughout evolution. For this purpose, the ventral processes of C6 in extinct and extant Equus specimens in museums and research/educational facilities were examined. The findings revealed the CVT of C6 was present in those extinct and extant specimens examined, and that its absence was only evident in modern horses. This implies that the absent CVT manifested post-domestication. Although the clinical significance is unknown, the relevance might be considered when reporting on diagnostic images of C6, and especially, for potential buyers in pre-purchase cases. In this study, we examined the ventral process of C6 in extinct and extant Equus (sister taxa to Equus ferus caballus only) with the purpose of describing normal morphology and identifying anomalous variations relevant to recent studies describing a congenital malformation in E. ferus caballus. Overall, 83 specimens from 9 museums and 3 research/educational facilities were examined, totalling 71 extinct specimens from 12 species and 12 extant specimens from 5 species. The lateral view revealed that a large convexity exists in the ventral process between the cranial ventral tubercle (CrVT) and the caudal ventral tubercle (CVT) in the earliest ancestor, Hyracotherium grangeri, from 55 mya, which receded throughout the millennia to become a smaller convexity in E. ferus caballus and the sister taxa. The CrVT is visibly shorter and narrower than the CVT, with a constricted section directly ventral to the transverse process, essentially demarcating the CrVT and CVT. No congenital malformations were evident. As the ventral process of C6 is an integral component for muscle attachment in supporting the head/neck during posture and locomotion, this would indicate that the caudal module in the cervical column might be compromised when a partial or complete absence of the CVT is detected via radiographs in modern E. ferus caballus. [ABSTRACT FROM AUTHOR]

Populations of feral horses (Equus ferus caballus) in the western United States have increased during the past decade, consequently affecting co‐occurring wildlife habitat. Feral horses may influence 2 native wildlife species, greater sage‐grouse (Centrocercus urophasianus; sage‐grouse) and pronghorn (Antilocapra americana) through mechanisms of habitat alteration and competition. Wyoming, USA, contains the largest populations of pronghorn and sage‐grouse of any state and also has the highest degree of range overlap between feral horses and these species. Consequently, the effects that horses may have on pronghorn and sage‐grouse populations in Wyoming have implications at local, state, and population‐wide levels. Managers need information concerning habitat selection and space use overlap among these species to develop appropriate management strategies; yet this information is absent for most feral horse management areas. To address this knowledge need, we attached global positioning system (GPS) transmitters to horses, pronghorn, and sage‐grouse within the greater Bureau of Land Management–Adobe Town Herd Management Area in southern Wyoming and northern Colorado, USA, between 2017 and 2021 to evaluate habitat selection and space use of all species during 3 biologically relevant seasons: spring (Apr–Jun; sage‐grouse breeding, nesting, and early‐brood rearing; pronghorn late gestation and early parturition), summer (Jul–Oct; sage‐grouse summer and late‐brood rearing; pronghorn late parturition and breeding), and winter (Nov–Mar; non‐breeding season). Feral horses selected flatter slopes and shorter mean shrub height across all seasons and were closer to water in spring and summer. Pronghorn habitat selection was similar to horses, but they also avoided oil and gas well pads year‐round. During spring, sage‐grouse selected greater herbaceous cover, flatter slopes, and areas farther from well pads. In summer, sage‐grouse selected greater mean shrub height, flatter slopes, and were closer to water. In winter, sage‐grouse selected flatter slopes and areas with greater vegetation production during the preceding summer. Our results indicate strong year‐round overlap in space use between horses and pronghorn, whereas overlap between horses and sage‐grouse is greatest during the summer in this region. Consequently, managers should recognize the potential for horses to influence habitat quality of pronghorn and sage‐grouse in the region. [ABSTRACT FROM AUTHOR]

Abstract The objective of this work was to determine how different types of gait affect the physiological and thermographic responses of Pantaneiro horses (Equus ferus caballus) subjected to field conditions under high environmental temperatures. Ten horses were evaluated in a double 5x5 Latin square experimental design, with five gait types: walk, trot, extended trot, gallop, and extended gallop. The following physiological measures were determined immediately after exercise: heart and respiratory rates, blood lactate content, and rectal temperature. Body surface temperatures were evaluated using an infrared camera. The walk, trot, and extended trot were the most adequate gaits for Pantaneiro horses to maintain thermoregulation within the physiological norms under conditions with a high air temperature. The temperatures obtained in the eye and elbow regions show the best predictive capacity for physiological parameters.

Horses went through functional differentiation during their evolutionary and reproductive development, however, some body parts continued to improve their specificity for speed. Regarding this, we evaluated by morphometric analysis the relationship between limb section (LS) differences in the appendicular structures of horses. Two hundred and seven (n = 207) adult horses of different breeds and sex were selected. The limb section was measured by identification of topographic palpable skeleton landmarks with a measurement tape (centimetres). Quantitative variables (limb section) were analysed with PAST Paleontological Statistics Version 3.16. Spearman's ordinal or non‐parametric correlation coefficient was used to study the relationship between the limb section of each variable (p < 0.05), with a low coefficient of variation (<30%). In 45 analysed correlations, 35 were statistically significant and 10 were discarded because p > 0.05. These results show that most variables were correlated with each other. As a result, we can imply that some LS of the horse's limbs are correlated with each other, positively or negatively and to a different degree. In conclusion, the correlations between LS lengths determine the size and shape of each horse, making individual horses unique and unrepeatable. [ABSTRACT FROM AUTHOR]

The growing population of free-roaming horses (Equus ferus caballus) on western public rangelands has necessitated that federal agencies, such as the Bureau of Land Management (BLM) and U.S. Forest Service, develop novel approaches to curb growth including reproduction management. However, bureaucracy has hindered effective research and application of horse management on public lands and examples on private lands may present new solutions. Here we present the history and current population management strategy for the Wild Horse Ranch (WHR) located in southeastern Wyoming, USA, as an example of an ongoing private entity managing horses. Prior to 1985, this ~6,000-ha ranch was used historically for domestic sheep (Ovis aries) production, and after 1985, for yearling cattle (Bos taurus). In 2005, geldings (i.e., castrated males) and mares were purchased from BLM by WHR and introduced to the ranch in conjunction with the development of home sites. In 2019, landowners formed the Wild Horse Preservation Society (WHPS) to enhance horse management and care. The WHPS uses multiple approaches to manage population growth including castrating stallions and treating mares with chemical contraception through partnerships with veterinarians and other stakeholders. In addition, WHPS feeds supplemental hay to horses in severe winter months, provides water during the summer, monitors rangeland vegetation, horse diets, and cares for abandoned foals or geriatric horses. The WHPS is a network of board members and landowners that is working for the betterment of horse welfare and rangeland health and is situated to be a leading entity and example in the area of free-enterprise free-roaming horse reproduction management. [ABSTRACT FROM AUTHOR]

Free-roaming horses (Equus ferus caballus; horses) inhabit public rangelands located primarily in 10 western U.S. states. Recent horse population increases are impacting rangeland ecosystems, native wildlife species and their habitats, and exacerbating conflicts with domestic livestock grazing. While contraceptives and physical sterilization are promising options to manage horse herd levels, public opinion concerning the use of fertility control is not well understood. To better inform policymakers, we completed a rigorous study of a random sample of public land stakeholders across the United States (n = 3,500) in 2020 using a Likert scale online survey to assess their level of agreement with the general use of reproductive controls and their preferences regarding 4 available reproductive control options. We used chi-square likelihood ratio tests to determine the associations between the knowledge of horse origins in North America and horse management in the United States, and public support of contraception and sterilization methods to control horse populations. We also assessed the associations between survey responses and respondent demographics. Most respondents either "somewhat agreed" or "strongly agreed" with the use of contraceptives to control horse birth rates (36.6% and 26.9%, respectively) when no specific type of contraceptive was described. Respondents who believed horses were native to North America "strongly agreed" with the statement regarding the use of contraceptives less often (22.2%) than respondents who recognized that European explorers introduced horses (36.6%) or believed horses arrived by crossing a land bridge (35.8%); however, this association exhibited very low power to predict the response (λ < 0.1). Similarly, while there were some associations indicated by chi-square analyses between demographic variables and support for contraceptives, these associations exhibited very low power to explain the responses. When asked to rank 4 generalized population control options, more respondents ranked physical sterilization as their preferred option (37.1%). There was an association between age and ranking order of sterilization. For ages 18--53, the range was 40.6-45.3%, significantly more than older ages, 54 to ≥73, where the range was 31.1-33.8%. Knowledge did not influence the preference for control options. Our results suggest that our respondents were more supportive of the use of contraceptives or sterilization, when described in generalities, to control the birth rates in free-roaming horses. Our research provides policymakers with objective, novel insights into public knowledge and perceptions concerning the population control of free-roaming horses on designated western rangelands. We encourage the federal, state, and tribal agencies charged with the management of free-roaming horses to develop and deliver outreach programs to better educate public land stakeholders about the ecological and economic impacts of free-roaming horses on western landscapes and efficacy of available population management options to mitigate impact and sustain herds. [ABSTRACT FROM AUTHOR]

The horse (Equus ferus caballus), originally native to North America, became extinct on the continent approximately 10,000 years ago. Horses that migrated from North America to Eurasia across the Bering Strait continued to evolve and were domesticated along with burros (E. asinus). Both species were then transported to the Americas where they were intentionally released or escaped into the wild, forming feral herds. The Wild Free-Roaming Horses and Burros Act of 1971 (WFRHBA) provided federal oversight and protection for feral horses and burros (hereafter, free-roaming equids) that inhabited designated areas on public lands in the western United States. The Bureau of Land Management (BLM) estimated in 2019 that >90,000 free-roaming equids inhabited 29 million ha on 177 designated herd management areas (HMAs). This population estimate exceeds the designated appropriate management level (AML) of 26,785. To provide BLM managers with insights regarding stakeholder knowledge and perceptions about the management of free-roaming equids in a western U.S. state where HMAs exceed AML, in 2020 we surveyed faculty, staff, and students at the state land-grant university (i.e., Utah State University [USU]). We hypothesized that, because the WFRHBA was passed in 1971, older respondents and those with natural resources education would be more informed and supportive of active free-roaming equid management, such as herd reduction. We received 959 responses (response rate of 12.5%) to our survey (i.e., 14% faculty, 14% staff, and 72% students). Most respondents (60%) were unaware of the WFRHBA, and >50% were unaware that free-roaming equids were protected. Over 45% of our respondents were unsure of HMA AML status or population growth rates. Furthermore, most respondents (65%) did not know that free-roaming equids are ecologically considered feral. Older respondents and those with rural backgrounds and natural resources education were more informed. Our results highlight the need for improved outreach and communication efforts regarding the issues and consequences of free-roaming equid management approaches. [ABSTRACT FROM AUTHOR]

Many wild horse (Equus ferus caballus) populations that inhabit designated federal land in the United States currently exceed management objectives. Overabundant wild horse populations can adversely impact the ecosystem, native wildlife, and other land uses. Unfortunately, there is not a universal solution, as each impacted area may differ ecologically, economically, socially, and politically. Wild horse management is not just a 1-time project but a long-term program where buy-in is needed from the federal and state agencies, local governments, and private partners. Local county governments and private partners can have important insights and significant influence on the development and success of local wild horse management strategies. The combined involvement of local government and stakeholders can have a wide range of benefits including increasing capacity for management, developing new management and placement techniques, and creating authentic program branding and outreach for better placement success. Partners can often complete projects in tighter time frames, find employees, and experience less government red tape in implementation. Buy-in from the local community can also decrease the amount of negative feedback during management implementation and create a support network to counteract the negative aspects of management. Located in the northeast corner of the state of California, USA, Modoc County recognized early on the need for local government participation in conversations and decisions surrounding wild horses and their management on the Devil's Garden Plateau Wild Horse Territory (WHT). The county implemented a coordinated planning and government-to-government communication process starting in 2011 to engage the Modoc National Forest, which manages the WHT, in meaningful solution-based dialogue. This paper offers examples of unique collaborative opportunities and solutions that have been successfully used in Modoc County to develop and implement a wild horse management plan. In the years since it was adopted, this plan has halted population growth and started to return the population to the appropriate management level on the Devil's Garden Plateau. [ABSTRACT FROM AUTHOR]

Domestic livestock grazing is the dominant land use on much of the current range inhabited by greater sage-grouse (Centrocercus urophasianus; sage-grouse) in the western United States. Nonnative feral horses (Equus ferus caballus) also inhabit important sage-grouse seasonal habitats. Overabundant feral horse populations and improper grazing by domestic cattle (Bos taurus) can impact the health of sagebrush (Artemisia spp.) and desert shrub rangeland communities and native wildlife. These impacts to sage-grouse can be exacerbated when they affect late brood-rearing habitat, which provide the forbs and arthropods required to fledge broods. Managers require better information regarding the extent of these impacts. In 2020, we assessed the potential impact of feral horses and domestic cattle on sage-grouse late brood-rearing habitats in western Utah and eastern Nevada, USA. We acquired late brood-rearing location data from sage-grouse marked with global positioning system and very-high frequency radio-transmitters from 2016 to 2020 for North Utah data, 2017 to 2018 for South Utah data, and 1961 to 2017 for both east and west Nevada data to delineate late brood-rearing habitats. Using these location data, we compared 8 sites (4 pairs) within horse and non-horse use areas to assess sage-grouse habitat quality characteristics between areas that have been predominantly horse and cattle grazed versus sites that have been predominantly cattle grazed. For each pairing, 1 site was located within and the other outside of a Bureau of Land Management herd management area boundary, and both sites shared similar habitat characteristics (i.e., topography, dominant vegetation, soils, and climate) and selection probability for broods. We collected vegetation and dung count data at each site to assess characteristics related to habitat quality for sage-grouse brood-rearing, based on ungulate presence. We used a mixed model analysis of variance to detect differences between each paired site comparison (α < 0.01). Horses or evidence of horse presence (i.e., dung) were not detected at our non-horse sites allowing for an unbiased comparison between paired sites. Cattle presence was noted at all our paired sites. Average annual grass frequency was 0.74 in horse and 0.17 in non-horse use areas (P = 0.20), and average annual grass cover was 4.0% compared to 0.2% in horse use areas (P = 0.32). Average annual grass biomass was 0.45 kg/ha in horse and 0.04% in non-horse use areas (P = 0.34). Vegetation height was 44.2 cm in nonhorse compared to 34.5 cm in horse use areas (P = 0.23). These results suggest that increased ungulate grazing and year-long use of late brood-rearing habitat by feral horses coupled with livestock grazing may impair habitat suitability, particularly considering ecological impacts from invasive plant species. Our results suggest that managing late brood-rearing habitats to reduce the frequency and intensity of year-long grazing by feral horses can be best accomplished by reducing horse numbers and the seasonal distribution of grazing by domestic livestock. [ABSTRACT FROM AUTHOR]

We analyzed 122 Gray Wolf (Canis lupus) scats, collected at all seasons during 2013-2017, to determine what wolves were eating in two adjacent study areas of the Chilcotin region, British Columbia: Brittany Triangle and Nemiah Valley. Freeranging horses (Equus ferus caballus), Mule Deer (Odocoileus hemionus), Moose (Alces americanus), and small mammals contributed to wolf diet throughout the year. In both study areas, horse appeared more frequently than other species in occurrence-per-faeces (OF) and occurrence-per-item (OI) analyses. Horse occurred in 58 of 97 wolf scats from Brittany (OF 59.8%, OI 52.7%), deer in 26 (OF 26.8%, OI 23.6%), small mammals in 17 (OF 17.5%, OI 17.3%), Moose in four (OF 4.1%, OI 3.6%), and bird and fish minimally (both OF <2.5%, OI <2.5%). The sample size in the more human-developed Nemiah Valley was too small to estimate reliable patterns, but results suggest a similar ranking of dietary items. Domestic Cattle (Bos taurus), available in both study areas, appeared infrequently (combined area OF <3.5%, OI <3.0%). Based on our scat findings, free-ranging horses were a regular dietary item for wolves in the area. Studies elsewhere have found that, where wolves and free-ranging horses are sympatric, a predator-prey relationship exists. [ABSTRACT FROM AUTHOR]

Context. Mustering (gathering) feral horses (Equus ferus caballus) often cause mortalities, yet cause-specific details are lacking. Aims. Given the need to optimise horse welfare, we analysed public horse muster data from the USA to understand specific causes of mortalities. Methods. We coded 393 individual horse mortality reports for 92 cause-specific mortality terms (keywords informing the deciphering of specific causes of mortality classified as anatomical, causal or conditional) and demographic details (age, sex, and body condition). Data were derived from 50 musters across seven states with at least one horse mortality. Musters were coded for type (helicopter or bait), emergency or regular planned efforts, and number of horses mustered and shipped daily. Key Results. More horses were euthanased than died naturally (330 (84.0%) and 39 (9.9%) respectively), and more horses had chronic than acute conditions (317 (80.7%) and 76 (19.3%) respectively), with both trends holding for both sexes and across ages. Body condition scores (BCS) for female horses were skewed low, whereas male horse BCS data were more normally distributed. Female horses had lower BCS than did male horses (P, 0.001). On average, each horse mortality had two cause-specific mortality terms, ranging from 1 to 7. Only 57 horses (14.5%) had terms describing anatomy, cause and condition, concurrently. Phi coefficients (j; indicators of fidelity and constancy) for cause-specific terms were related to demographic or muster attributes and were analysed with post hoc ANOVA tests of estimated marginal means to allow for ranking. Female horses were most often described as emaciated, weak, and starving, whereas male horses were described as lame, arthritic, blind or dangerous. Bait trapping and emergency musters included horses that were starving, dehydrated and weak. Conclusions. Generally, disorders associated with legs and feet, eyes, necks and nutrition were the most prevalent cause-specific mortality issues. Using a machine learning approach, validation and test accuracy were high for predicting euthanasia versus natural mortalities, but low for predicting acute versus chronic mortalities. Individual horse demographics or daily muster features had a greater relative influence than did capture type or emergency status in both comparisons. Implications. These results provide practical insight for potential cause-specific mortalities relative to demographics and muster techniques. [ABSTRACT FROM AUTHOR]

Assisted reproductive technologies have been used in zoos and breeding centres to preserve rare and endangered species of wild animals over the past three decades. The most common way to preserve the genetic material of farm and wildlife animals is to create cryobanks of semen producers and embryos. Studies of domestic species under controlled conditions provide an excellent opportunity to develop effective semen handling techniques for application to wild species of the genus Equus. The All-Russian Research Institute for Horse Breeding (ARRIH) began studies on the cryopreservation of genetic resources in the early 1950s. In 1954 the ARRIH got the world's first foal from the artificial insemination by cryopreserved sperm. The collection of genetic resources of ARRIH has been successfully working since 1972 and contains nowadays cryopreserved sperm from 56 stallions of 16 breeds of domestic and foreign selections. Freezing and subsequent thawing of stallion sperm leads to a decrease in progressive sperm motility and an increase in the number of sperm with structural pathologies. Electron microscopy is one of the most accurate methods used to assess the structural integrity of sperm. We conducted an electron microscopic study of native and cryopreserved sperm of 35 stallions of riding and trotting breeds, aged 4 to 22 years (mean age 11.3 ± 0.9 years). We found that organoids with a denser structure are more resistant to freezing and subsequent thawing of sperm. The use of stallion sperm cryopreservation according to the standard technology of ARRIH leads to a decrease in the number of sperms with intact heads by an average of 19.7%, and the share of sperm with intact heads in cryopreserved sperm is 49.1 ± 2.7% (p < 0.001). The most negatively cryopreservation of semen affects an acrosome of sperms. The main pathologies of acrosomes in sperm cryopreservation are acrosome hypoplasia and its degradation (secondary absence of acrosome). The number of spermatozoa with acrosome hypoplasia and the absence of internal content after cryopreservation increases by 20.9%, and the share of such sperms is 31.7% in thawed sperm (p < 0.001). The number of sperm with acrosome degradation during sperm freezing and thawing increases by 10.4%, and is 18.6 ± 2.4% in average. The share of spermatozoa with normal mitochondrial structure in native sperm is 89.3 ± 2.0% in average, in cryopreserved sperm – decreases by 6.5%. The share of spermatozoa with normal axoneme after cryopreservation decreases slowly, averaging by 4.4% and is 81.4 ± 2.0%. Some of the available assisted reproduction technologies will need to be further optimised in domestic horses before they can be applied to the endangered Przewalski's horse Equus ferus przewalskii.

To successfully manage population growth rates of free‐roaming horses (Equus ferus caballus), an effective, long‐acting contraceptive could be beneficial. We evaluated the efficacy and safety of an intrauterine device (IUD) in a breeding trial using seasonal pasture assemblages of 2 males individually pastured in large enclosures (~81 ha) each with 10 females per male. The study took place at a large animal research facility at Oklahoma State University in Stillwater, Oklahoma, USA. Specific objectives of the study were to evaluate the effectiveness of IUDs in preventing pregnancy over 20.5 months with return to fertility assessed over the subsequent 6 months and to evaluate potential effects of this IUD on ovarian function and uterine health (e.g., endometrial inflammation, infection, fibrosis). We developed a Y‐design IUD, made of silastic elastomer, and set the desired retention rate at 75%. After procurement of endometrial biopsies, we inserted IUDs into the uteri of 20 females and examined them via transrectal ultrasound every 2 weeks for detection of the device and assessment of uterine health. After 20.5 months we removed the remaining 15 IUDs, obtained a second endometrial biopsy for comparision, and returned the females to their respective males for continued breeding in efforts to assess uterine return to health as indicated by pregnancy rates. The Y‐design IUD met the 75% retention rate goal, with 100% contraception in females that retained the device; 12 of 20 treated females became pregnant (i.e. returned to fertility) after removal of the IUD. Based on these results, we conclude that the Y‐design IUD is a safe and effective device to control fertility in free‐roaming horses. © 2021 The Wildlife Society. Our Y‐design silastic elastomer IUD maintained a 75% retention rate and prevented establishment of pregnancy over 20 months, but ovarian cyclicity was not altered; therefore, normal estrus and diestrus phases of the female's estrous cycle were maintained, with breeding activity occurring during estrus. Once we removed the IUDs 12 females became pregnant, conveying retention of fertility. [ABSTRACT FROM AUTHOR]

Feral horses (Equus ferus caballus) in the western United States are managed by the Bureau of Land Management (BLM) and United States Forest Service in designated areas on public lands with a goal of maintaining populations in balance with multiple uses of the landscape. Small, isolated populations can be at risk of extirpation from stochastic events and deleterious genetic effects resulting from inbreeding and reduced heterozygosity. The genetic diversity of feral horse herds is periodically monitored using blood or hair samples collected during management gathers (i.e., occasions when the herd is rounded up). We conducted a study to examine genetic characteristics of the feral horse population at the BLM Little Book Cliffs Herd Management Area (HMA) in Colorado, USA, using non‐invasively collected fecal samples. Additionally, we explored whether genotypes could be used to document space use and potential sub‐population development. We used a random sampling scheme, walking transects in sampling areas covering most of the HMA to find and collect fecal samples of all ages, except those that were deteriorating. We collected >1,800 fecal samples from across the study area in May, August, and October 2014. We then identified unique individuals using a suite of microsatellite loci. Our estimates of genetic diversity from fecal samples were higher than those reported from blood and hair samples taken during recent horse gathers, likely because our sample size and spatial distribution was larger. Genotypes revealed that some individuals were found only in certain parts of the study area and at a higher proportion than random; thus, they could be considered residents in those sampling areas. Using discriminant function analyses, we detected 5 genetic groups in the sample population, but these did not correspond to individuals in specific parts of the study area. Our results support the use of fecal DNA to augment direct observations of horse presence and could be used to detect habitat use and areas of high density. Non‐invasive techniques such as fecal DNA sampling can help managers decide whether new individuals need to be translocated to a closed population to maintain genetic diversity without the human safety and animal welfare concerns associated with gathers and invasive techniques. © 2021 The Wildlife Society. We found higher estimates of genetic diversity from feral horse fecal samples collected non‐invasively than those reported from blood or hair samples collected during a gather; genotypes derived from fecal samples can be used to show feral horse space use. Fecal samples can therefore be used to examine genetic characteristics of a horse herd in the absence of a gather and can elucidate areas of high horse use. [ABSTRACT FROM AUTHOR]

Feral horse (Equus ferus caballus) populations on public rangelands in the western United States threaten forage production for livestock and wildlife habitat. Interference competition between feral horses and heterospecifics at watering sources can have negative effects on livestock and wildlife. Researchers have documented altered timing and behavior of wild ungulates at water sources when horses were present. The few studies examining these interactions have infrequently occurred within areas specifically managed for feral equids and have not occurred in sites with cattle. We used motion‐sensitive cameras at 8 watering sources to document watering activity patterns and construct indices of temporal overlap among feral horses, cattle, elk (Cervus canadensis), mule deer (Odocoileus hemionus), and pronghorn (Antilocapra americana) within the Adobe Town Herd Management Area in southern Wyoming, USA, between June and September 2018 and 2019. Feral horses, cattle, and pronghorn exhibited a high degree of temporal overlap (>79%) in water use, with feral horses and pronghorn exhibiting the highest estimated percent overlap (88.1%, 95% CI = 86.5–89.6%). Mule deer and elk watering activity also overlapped with horses and cattle but to a lesser degree (<55%). Feral horses spent a mean of 16.7 ± 30.5 (SD) minutes during a watering event and were present at a given water source on average 4.5 ± 6.3% and up to 34.9% of the day, which is less than reported in previous studies. Cattle spent on average 23.5 ± 44.9 minutes during a watering event, and were present on average 4.2 ± 7.7% and up to 42.4% of the day at a single water source. Results of generalized linear mixed‐effects models indicated that number of conspecifics was the strongest predictor of visit duration for pronghorn and horses; hour of the day and group size of heterospecifics were informative, but less important, variables. There was no difference in peak visitation time for any species between sites of high versus low horse or cattle use. Despite temporal overlap, we did not find evidence of interference competition between feral horses, cattle, and pronghorn. We recommend future examination of interference competition and its biological consequences between introduced and native ungulates at water sources of varying size across sites, equid population levels, and livestock stocking rates. © 2020 The Wildlife Society. Feral horses in the Adobe Town Management Area, Wyoming, USA, spent less time at water than reported in previous studies and strongly overlapped in watering activity with pronghorn and cattle, but not elk or mule deer. Despite temporal overlap, we did not find any evidence of interference competition between feral horses, cattle, and pronghorn. [ABSTRACT FROM AUTHOR]

The development of next-generation sequencing technologies has spurred a surge of research on bacterial microbiome diversity and function. But despite the rapid growth of the field, many uncertainties remain regarding the impact of differing methodologies on downstream results. Sample storage temperature is conventionally thought to be among the most important factors for ensuring reproducibility across marker gene studies, but to date much of the research on this topic has focused on short-term storage in the context of clinical applications. Consequently, it has remained unclear if storage at −80 °C, widely viewed as the gold standard for long-term archival of feces, is truly required for maintaining sample integrity in amplicon-based studies. A better understanding of the impacts of long-term storage conditions is important given the substantial cost and limited availability of ultra-low temperature freezers. To this end, we compared bacterial microbiome profiles inferred from 16S V3–V4 amplicon sequencing for paired fecal samples obtained from a feral horse population from Sable Island, Nova Scotia, Canada, stored at either −80 °C or −20 °C for 4 years. We found that storage temperature did not significantly affect alpha diversity measures, including amplicon sequence variant (ASV) richness and evenness, and abundance of rare sequence variants, nor presence/absence, relative abundances and phylogenetic diversity weighted measures of beta diversity. These results indicate that storage of equine feces at −20 °C for periods ranging from a few months to a few years is equivalent to storage at −80 °C for amplicon-based microbiome studies, adding to accumulating evidence indicating that standard domestic freezers are both economical and effective for microbiome research.

Radio-collars and other radio-marking devices have been invaluable tools for wildlife managers for >40 years. These marking devices have improved our understanding of wildlife spatial ecology and demographic parameters and provided new data facilitating model development for species conservation and management. Although these tools have been used on virtually all North American ungulates, their deployment on feral horses (Equus ferus caballus) or burros (E. asinus) has been limited. To determine if radio-collars and radio-tags could be safely deployed on feral equids, we conducted a 1-year observational study in 2015 to investigate fit and wear of radio-collars on feral horses and burros kept in pastures/pens at the Bureau of Land Management contracted adoption facility in Pauls Valley, Oklahoma, USA. We assessed the impact of radio-collars and transmitter tags on individual behavior, body condition, and evaluated neck surface for effects. We tested 2 radio-collar shapes (teardrop and oval) and a radio-tag (i.e., avian backpack) braided into the mane and tail of horses. Behavior of mares did not differ between radio-collared (n = 12) and control (uncollared; n = 12) individuals. Despite the small sample size, collared burro jennies (n = 4) spent more time standing than controls (n = 4). Stallions wearing radio-collars (n = 9) fed less, moved less, and stood more than controls (n = 8). During the study, we did not detect injuries to the necks of mares or burro jennies, but stallions developed small sores (that healed while still wearing radio-collars and re-haired within 3 months). Two radio-collars occasionally flipped forward over the ears onto the foreheads of stallions. Although our study confirmed that radio-collars could be safely deployed on captive mares and jennies, stallions proved challenging for a variety of reasons. While our conclusions were optimistic, longer studies will be required to ensure radio-collar safety on free-ranging feral horses and burros.

The development of next-generation sequencing technologies has spurred a surge of research on bacterial microbiome diversity and function. But despite the rapid growth of the field, many uncertainties remain regarding the impact of differing methodologies on downstream results. Sample storage temperature is conventionally thought to be among the most important factors for ensuring reproducibility across marker gene studies, but to date much of the research on this topic has focused on short-term storage in the context of clinical applications. Consequently, it has remained unclear if storage at -80 °C, widely viewed as the gold standard for long-term archival of feces, is truly required for maintaining sample integrity in amplicon-based studies. A better understanding of the impacts of long-term storage conditions is important given the substantial cost and limited availability of ultra-low temperature freezers. To this end, we compared bacterial microbiome profiles inferred from 16S V3-V4 amplicon sequencing for paired fecal samples obtained from a feral horse population from Sable Island, Nova Scotia, Canada, stored at either -80 °C or -20 °C for 4 years. We found that storage temperature did not significantly affect alpha diversity measures, including amplicon sequence variant (ASV) richness and evenness, and abundance of rare sequence variants, nor presence/absence, relative abundances and phylogenetic diversity weighted measures of beta diversity. These results indicate that storage of equine feces at -20 °C for periods ranging from a few months to a few years is equivalent to storage at -80 °C for amplicon-based microbiome studies, adding to accumulating evidence indicating that standard domestic freezers are both economical and effective for microbiome research. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate some conformation traits and body indices in two Romanian Gidran stud farms: Tulucești and Cislău. The target of this study is to establish an optimal breeding selection and mating program, which will lead to the modification of the genetic structure in order to increase population performances. The targeted conformation traits were: height at withers, thorax perimeter, and cannon bone circumference. In all cases, the coefficient of variation was low (under 10%) for all studied characters, and this indicates that in the studied horse population a continuous genetic improvement activity has been carried out over several generations. Comparing the thorax perimeter value of Romanian Gidran mares (184.2 cm) with the values reported in Croatian and Hungarian populations, we can conclude that Croatian and Hungarian mare population recorded higher values (190.3 and 192.7 cm). Regarding the height at withers, the mean height in the Romanian population (161.8 cm) was similar with that reported for Croatian population (161.9 cm), Hungarian population (161.7 cm). The cannon bone circumference values were similar: 20.4 cm in Romanian mares, 20.5 cm in Croatian mares and 19.9 cm in Hungarian mares. [ABSTRACT FROM AUTHOR]

Inflammasome, a cytosolic multi-protein complex, assembly is a response to sensing intracellular pathogenic and endogenic danger signals followed by caspase-1 activation, which maturates precursor cytokines such as interleukin (IL)-1β. Most inflammasome research has been undertaken in humans and rodents, and inflammasomes in veterinary species have not been well-characterized. In this study, we observed the effects of well-known inflammasome activators on equine peripheral blood monocytes (PBMCs). The NLRP3 inflammasome triggers include ATP, nigericin, aluminum crystals, and monosodium urate crystals, and NLRP3 activation induces IL-1β secretion in a dose-dependent manner. Activators of NLRC4 and AIM2 inflammasomes include cytosolic flagellin and dsDNA, and their activation induces IL-1β secretion. The bacterial inflammasome triggers Salmonella Typhimurium and Listeria monocytogenes also induce IL-β releases. To elucidate the role of potassium efflux as an upstream signal of NLRP3 inflammasome activation, equine PBMCs were treated with blockers of potassium efflux in the presence of NLRP3 triggers. As a result, the IL-1β secretion stemming from equine NLRP3 inflammasome activation was not completely attenuated by the inhibition of potassium efflux. Taken together, the results indicate that equine PBMCs normally secrete IL-1β in response to well-known inflammasome activators, although equine NLRP3 inflammasome activation might not be dependent on potassium efflux. [ABSTRACT FROM AUTHOR]

Inter-individual variation in juvenile body size can have important consequences for individual fitness, population dynamics, and adaptive evolution. In wild vertebrate populations, larger juvenile size is usually expected to be selected for. However, understanding how such selection may translate into adaptive evolution requires an understanding of the genetic underpinnings of early development and the factors modulating selection. In this study, we characterised the genetic basis of and selection pressures acting upon juvenile body size in a large insular population of feral horses on Sable Island, Canada, to gain insights into the evolution of juvenile body size in wild vertebrate populations. We used pedigree-based quantitative genetic 'animal models' to quantify the sources of phenotypic variation in withers-knee length, and assessed the influence of maternal age, sex, and temporal (birth year) and spatial environmental heterogeneity in modulating overwinter survival selection. We found that withers-knee length is moderately heritable and that there was a significant positive genetic correlation between males and females. There was no indication of directional selection in a pooled-sex analysis, but we did find evidence for significant sexually antagonistic selection, with a tendency for smaller body size to be favoured in males and larger body size to be favoured in females. These results suggest that juvenile body size has the potential to evolve in this population, and that selection on juvenile size may play an important role in modulating sex-specific contributions to population dynamics. However, our results also suggest that there is unlikely to be evolutionary change in the mean body size of Sable Island foals. [ABSTRACT FROM AUTHOR]

In this paper we analyse the taphonomic signatures of captive jaguars (Panthera onca) in order to explore the potential of experimental frameworks to distinguish between different felid agents in carnivore-altered palaeontological and archaeological bone assemblages. Many papers have considered carnivore ecology and the bone altering behaviour of different animals since the development of taphonomic research since the 1980's, as part of the hunter vs scavenging debate to understand early hominin sites. Hyenas have been the most studied carnivore, followed by felids and lastly canids. Within felids, lions and leopards have been the focus of most research, whereas other agents, such as jaguars or tigers are still relatively uncharacterised taphonomically. Here we present the results of an experimental feeding program to assess the nature and extent of alterations that captive jaguars can produce on horse (Equus ferus caballus) appendicular bones. Working with captive animals has some limitations, namely the generally greater extent of alterations on captive-analysed assemblages in relation to their wild counterparts. Despite this issue, we aim to start developing a broader referential framework of felid ethology that includes jaguars, a relevant taphonomic agent for understanding bone assemblages of the European and American Pleistocene. Therefore, in this preliminary study on the taphonomy of jaguars, we aim to show their prowess as bone-altering agent, capable of generating tooth-marks on long limb bone diaphyses and epiphyseal deletion. The taphonomic behaviour of jaguars has not been documented experimentally in any detail so far. [ABSTRACT FROM AUTHOR]

Ecological and social factors underpinning the inequality of male mating success in animal societies can be related to sex ratio, sexual conflict between breeders, effects of nonbreeders, resource dispersion, climatic conditions, and the various sequential stages of mating competition that constitute the sexual selection process. Here, we conducted an individual‐based study to investigate how local resource availability and demography interact with annual climate conditions to determine the degree of male mating inequality, and thus opportunity for sexual selection across two sequential reproductive episodes (harem and subsequent mate acquisition) in a naturally regulated (feral) horse population in Sable Island National Park Preserve, Canada. Using a 5‐year, spatially explicit, mark‐resight dataset and hierarchical mixed‐effects linear modeling, we evaluated the influence of adult sex ratio (ASR) on mating success and then tested for effects of freshwater availability, density, unpaired male abundance, and precipitation during each breeding season. Unpaired male abundance, freshwater availability, and ASR differed in their effects on male mating success according to year and selection episode. Opportunity for sexual selection in males associated with harem acquisition increased with ASR, and unpaired male abundance further explained weather‐related interannual variation after accounting for ASR. In contrast, once a harem was secured, ASR had little effect on male mating inequality in regard to acquiring additional females, while interannual variation in mating inequality increased with decreasing freshwater availability. Our findings show that local demography, resource availability, and weather effect opportunity for sexual selection in males differently depending on selection episode, and can attenuate or accentuate effects of ASR. [ABSTRACT FROM AUTHOR]

In Iceland, there is at least 1 horse for every 5 human inhabitants, mostly kept on uncultivated rangelands. Although the Icelandic horse is considered robust compared with other breeds, it is nevertheless susceptible to disease. Few studies have investigated the prevalence of intestinal parasites in horses in Iceland. The purpose of this study was to determine the prevalence of the tapeworm, Anoplocephala perfoliata, in horses in Iceland and to explore associations between intensity of infection and the severity of macroscopic pathological lesions in this population. In addition, the relationship between infection and geographical location in Iceland, horse age, and gender were investigated. The utility of a modified McMaster flotation method for identifying infected horses from fecal samples was also studied. The study sample consisted of 104 horses (aged 1–30 yr) slaughtered in 3 abattoirs in North and South Iceland during June and July 2016. The prevalence of A. perfoliata in the horses was 64.4%, with between 1–131 worms found in infected horses. The pathological changes in the horses associated with infection varied from mild (hyperemia in small areas) to severe (large ulcers and necrotic lesions coated with fibrin), and intensity of infection correlated with the size and type of pathological lesions in the intestines. No statistically significant associations between infection with A. perfoliata and geographical location, horse age, or horse gender were detected. The McMaster egg counting method used here was of very low sensitivity (7.4%) and was concluded to be inadequate for detection of A. perfoliata infection in horses. The prevalence of A. perfoliata in horses in Iceland in this study was found to be relatively high compared with results from many studies performed elsewhere in Europe. This may reflect the lack of treatment of horses in Iceland for this parasite, the environmental suitability for the intermediate mite host, and grazing management practices in Iceland. The high prevalence and association with pathology suggest that diagnosis of infection using a sensitive method, along with appropriate treatment, should be considered for horses in Iceland. [ABSTRACT FROM AUTHOR]

The Wild Free-Roaming Horses and Burros Act (WFRHBA) of 1971 established all “unbranded or unclaimed” equids on U.S. public lands as “living symbols of the historic and pioneer spirit of the West.” Today, >72,000 feral horses (Equus ferus caballus) and burros (E . asinus ; WHB) live on western U.S. public rangelands. The number of WHBs exceeds the Bureau of Land Management’s maximum Appropriate Management Level (AML) of 26,715 by a factor of approximately 2.7 and has nearly doubled from 2007–2015. The AML was set to balance WHB numbers with rangeland health and support other uses such as wildlife habitat and livestock grazing. Thus, public land management agencies must manage WHB under the multiple-use context. This becomes more problematic when WHB populations go largely unmanaged and excessive equid grazing negatively impacts rangeland vegetation, native wildlife, and livestock forage. In addition, approximately 46,000 WHBs exist in off -range holding facilities, further straining federal budgets. Contemporary management actions are being constrained by: (1) litigation that has stymied federal government WFRHBA enforcement eff orts, (2) public emotional concerns that lack reconciliation with the current situation, and (3) increasing complexity in the laws and subsequent amendments shaping WHB management policy. Collectively, these factors impede the implementation of concrete solutions to restore AML. Consequently, stakeholders are increasing polarized over how WHBs are or should be managed. While the ecological and animal health and welfare implications of unmanaged WHB populations are somewhat understood, publicly acceptable strategies to maintain healthy populations, healthy and functioning rangelands, and multiple uses that sustain wildlife and local communities remain unresolved.

Free-ranging or feral horses (Equus ferus caballus) were important to the livelihood of First Nations and indigenous communities in Canada. The early inhabitants of the boreal region of British Columbia (BC) capitalized on naturally occurring wildfires and anthropogenic burning to provide forage for free-ranging horses and manage habitat for wildlife. This form of pyric herbivory, or grazing driven by fi re via the attraction to the palatable vegetation in recently burned areas, is an evolutionary disturbance process that occurs globally. However, its application to manage forage availability for free-ranging horses has not been studied in northern Canada. Across Canada, there are varying levels of governance for feral and free-ranging horses depending on the provincial jurisdiction and associated legislation. The BC Range Act (Act) allows range tenure holders to free-range horses that they own for commercial operations on Crown land. Big-game guide outfitters as range tenure holders are provided grazing licences or grazing permits under the Act with an approved range use plan. Guide outfitters and other range tenure holders have incorporated fi re ecology as part of their rangeland management in mountainous portions of the boreal forest of northeastern BC to promote mosaics of vegetation height and species composition across the landscape to meet nutritional requirements of their free-ranging horses. Using resource selection function models, we evaluated the influence of pyric herbivory on boreal vegetation and use by horse herds occupying 4 distinct landscapes. We found that horses preferentially selected recently burned areas and areas that burned more frequently when they were available. We also found that horses avoided steep slopes and forest cover types. Fire and the ecological processes associated with it, including pyric herbivory, are important considerations when managing boreal rangelands in northeastern BC. Because historical fi re regimes of the boreal region of Canada differ from the arid regions of the United States inhabited by feral horses, the role of pyric herbivory in altering horse distributions in the United States is limited.

The number of feral horses (Equus ferus caballus) in the world has been estimated at 1.5–2 million, of which 5,000–10,000 occur in Argentina. Feral horses are considered an invasive alien species in Argentina, and as such, create a problem for biodiversity conservation. Only the population in Parque Provincial Ernesto Tornquist, Buenos Aires province, has been managed. In this paper, I discuss the conflicts between feral horse advocates, government authorities, and researchers that occurred after management actions were implemented and identify some factors that contributed to the conflict in positive and negative manners as well as some confusing concepts and ideas. I also summarize the studies that have been completed to describe this feral horse population demography and impact on biodiversity in Argentina. Lastly, I elaborate on the challenges impeding the future management of feral horses in Argentina.

Our understanding of the spatial ecology of feral horses (Equus ferus caballus ) and burros (E . asinus ) in the United States is limited. Robust location data are needed to better understand the permeability of Bureau of Land Management Herd Management Area boundaries, relative to feral horse movement patterns and home ranges. To increase our understanding of feral horse movement, in February to March 2017, we deployed global positioning system (GPS) collars on 14 females ≥5 years old that were captured in the Adobe Town Herd Management Area (ATHMA) of southcentral Wyoming, USA. Herein, we report initial results from movement data collected during summer (May 15 to September 15) 2017 for 9 horses. We limited our focus to these 9 horses because we received at least 2 months of continuous GPS location data from them during summer 2017. Feral horse daily movement distances averaged 9.0 km (SE = 0.3), and mean summer total home range size was 40.4 km2 (SE = 6.7). Of GPS location fixes obtained, 44.9% were outside ATHMA and 10.8% were on private land. Our results highlight the types of data that GPS collars can provide and illustrate the difficulties of managing free-roaming species such as horses and burros on landscapes with heterogeneous sociopolitical patterns. Expanded use of such technology on feral horses and burros in the United States will yield greater insight on spatial complexities constraining management.

There are currently >75,000 feral horses (Equus ferus caballus) and burros (E. asinus ) on U.S. public lands, yet the Appropriate Management Level (AML) is set at just under 27,000. Wildlife managers, conservation biologists, and livestock ranchers are concerned about the impacts that these free-ranging horses have on shared rangelands. Immunocontraceptive vaccines may have the greatest potential to regulate horse population numbers once AML is reached; however, the vaccine must have multi-year efficacy to be both technically feasible and cost-effective. Immunocontraception based on porcine zona pellucida (PZP)-specific antigens is highly tissue-specific, targeting the ova, and blocking sperm binding through antibody occupation of ZP receptors on the ova. ZonaStat-H and PZP-22 are PZP-based vaccines; however, their contraceptive efficacy does not last long enough to meet management needs. SpayVac® achieves multi-year efficacy with a single dose, without boosters, because the PZP antigens are encapsulated within liposomes (multi-layered, submicroscopic vesicles), which gradually release PZP glycoproteins to antigen-presenting cells over an extended period of time. We review results from SpayVac trials in horses and other species to deepen our understanding of how the vaccine works and how it may best be applied to regulate free-ranging horse populations at AML. We examine 3 studies in horses, which used different SpayVac formulations and delivery methods, to learn more about the relationship between antibody titers and contraceptive efficacy, as well as potential mechanisms of action (e.g., preferential stimulation of IgG4/7 antibody isotypes). Additional research to explore possible effects of injection site location, antigen purity, role of PZP antibodies, and different formulations (e.g., dose, adjuvant) is needed for efficacious application to free-ranging herds.

This commentary provides a brief review of the history of contraceptive research eff orts for feral horses (Equus ferus caballus) as well as the contraceptives and sterilization techniques currently available for feral horses. Porcine zona pellucida (PZP) immunocontraceptives have received the most attention and use over the past 40 years, but other treatments such as the GnRH vaccine Gonacon™-Equine are also available. Optimization of these treatments as well as the development of other molecular approaches, intrauterine devices, and surgical techniques is ongoing.

ABSTRACT It is not always practical to hand‐measure body size of free‐ranging animals. In recent years, parallel‐laser photogrammetry has become increasingly common for obtaining remote estimates of body size. However, it is unknown how well this technique might capture variation in body size of curvilinear features or whether the distance between parallel‐laser calipers is altered when projected onto a curved surface. We describe a photogrammetric system that may be useful for obtaining body‐size measurements from unrestrained large mammals that permit approach. We tested the use of parallel‐laser photogrammetry to estimate the size of curvilinear features in domestic horses (Equus ferus caballus) and identified morphometrics that explained variation in body weight. Despite projecting the lasers onto a curved surface (the barrel of a horse), we achieved accurate photogrammetric estimates of linear hand‐measurements. The curvilinear hand‐measurements also showed strong correlations (R2 ≥ 0.996) with their respective linear photogrammetric estimates, and most photogrammetric estimates had high reliability. Using 3 variables of body size, photogrammetric estimates and hand‐measurements explained 86.0% and 96.2% of the variation in weight, respectively. © 2015 The Wildlife Society.

Diseases of zoonotic origin have been seriously neglected in developing countries, without taking into account that this may have serious public health implications, particularly for Colombia, in recent decades there have been strong social changes that have involved, among other things, the increase of the tendency to the possession of companion animals including Equus ferus caballus, for which, the associated microbiota has been poorly studied in comparison with other animals. Therefore, we set ourselves the objective of identifying the bacterial and parasitic diversity associated with fecal matter of Equus ferus caballus. For this, independent samples were taken for each of the purposes, making the concentration of parasites using the Ritchie technique; Samples for bacterial isolation were processed and identified with the BD BBL CRYSTAL E / NF and GP Kit. For the analysis of the data, logistic regression was performed using Statgraphics. We were able to isolate 19 bacteria, of which six were explained by at least one of the variables taken into account. Nine of the isolated bacteria had not been previously reported for equines. Three genera of new parasites are reported for the species (Balantidium sp, Cyclospora sp and Taenia sp.) And four new for the country (Allantosoma sp, Blepharocorys sp, Cycloposthium sp. and Bundleia sp.) It is concluded that the variables taken into if they have influence on the incidence of some isolated microorganisms, in the same way new species of bacteria for Equus ferus caballus as well as parasites are reported. [ABSTRACT FROM AUTHOR]

In the current study, data of 930 horses was used and divided into four types of categories i.e. Draft, Wild, Sports and Race types. A set of ten microsatellite markers HTG10, ASB2, ASB17, HMS3, AHT4, HMS7, VHL20, AHT05, HTG4 and HMS6 were studied. Allelic frequency, total number of alleles, observed number of alleles, expected number of alleles, heterozygosity, Hardy-Weinberg equilibrium was calculated using GeneAIEX 6.502 software. Genetic structure of horse breeds was studied using STRUCTURE & STRUCTURE harvest software, while results were visualized by CLUMP and DISTRUCT software. Moreover, Phylogenetic analysis was performed using PHYLIP and data was visualized in MEGA 7. Maximum number of alleles was observed for sports category and most polymorphic markers among all types of horses was ASB17. The maximum and minimum values of inbreeding coefficient was found in wild and race horses respectively. Maximum observed heterozygosity was found in case of race horses; however, highest value of expected heterozygosity was found for sports horses. Present study showed that even with limited number of markers considerable level of genetic diversity between and among all types of horses was observed. [ABSTRACT FROM AUTHOR]

This commentary provides a brief review of the history of contraceptive research eff orts for feral horses (Equus ferus caballus) as well as the contraceptives and sterilization techniques currently available for feral horses. Porcine zona pellucida (PZP) immunocontraceptives have received the most attention and use over the past 40 years, but other treatments such as the GnRH vaccine Gonacon™-Equine are also available. Optimization of these treatments as well as the development of other molecular approaches, intrauterine devices, and surgical techniques is ongoing. [ABSTRACT FROM AUTHOR]

Management of wild horse (Equus ferus caballus) populations on western U.S. rangelands has been a challenge since horses were given legal protection through the passage of the Wild Free-Roaming Horses and Burros Act (WFRHBA) in 1971. Horses have no eff ective predators, and unmanaged populations can double in 4-5 years and triple in 6-8 years. In order to meet the multiple-use paradigm for managing public rangelands, the Bureau of Land Management (BLM) has limited horse population growth through the periodic capture and removal of animals. While the WFRHBA mandates disposal of captured horses through placement into private ownership and prompt destruction of any excess animals, administrative restrictions have prohibited the destruction of healthy horses for nearly the entire history of the management program. This has led to an ever-increasing number of unwanted horses maintained in captivity, which has required increasing Congressional appropriations. There are currently 44,000 horses in long-term captivity at an annual cost of approximately $50 million. Recently, Congress has denied requests from the BLM for further funding increases to support continued growth in the number of horses in long-term maintenance, obligating the BLM to dramatically curtail population management. Horse numbers on public rangelands are now rapidly increasing, and if left minimally managed will exceed the capacity of rangeland resources, resulting in serious degradation of these public lands for all other uses and eventually will result in large numbers of horses dying of starvation and dehydration. Horse advocates suggest this management crisis can be solved with the aggressive use of contraceptive technologies. Limitations in effi cacy and the logistics of administering contraceptives indicate that contraceptives can only slow population growth rates, but alone cannot decrease numbers. The BLM and other stakeholders are pressing for authorization to destroy excess horses but are facing public and Congressional opposition, with the potential that the status quo continues. A sustainable wild horse and burro (E. asinus; WHB) management program could be achieved by a combination of reducing the on-range population and treating adequate numbers of horses remaining on rangelands with contraceptives to reduce subsequent population growth rates. Under this scenario, the freeroaming horse population would produce a modest annual increment of horses, which could be removed and readily placed into private ownership. It has taken nearly half a century for the wild horse problem to reach this critical point, and any transition to a sustainable program will take time and additional resources. The fundamental challenge to developing a sustainable program will be solving the problem of the fate of excess horses. The policy decisions confronting us are historic, challenging, and controversial with a real danger of not fi nding the resolve to chart a new course for the WHB Program. If we fail and continue with the current policies, then horses, native wildlife, all stakeholders, and our public rangelands will pay a heavy price. [ABSTRACT FROM AUTHOR]

There are currently >75,000 feral horses (Equus ferus caballus) and burros (E. asinus) on U.S. public lands, yet the Appropriate Management Level (AML) is set at just under 27,000. Wildlife managers, conservation biologists, and livestock ranchers are concerned about the impacts that these free-ranging horses have on shared rangelands. Immunocontraceptive vaccines may have the greatest potential to regulate horse population numbers once AML is reached; however, the vaccine must have multi-year effi cacy to be both technically feasible and cost-eff ective. Immunocontraception based on porcine zona pellucida (PZP)-specifi c antigens is highly tissue-specifi c, targeting the ova, and blocking sperm binding through antibody occupation of ZP receptors on the ova. ZonaStat-H and PZP-22 are PZP-based vaccines; however, their contraceptive effi cacy does not last long enough to meet management needs. SpayVac® achieves multi-year effi cacy with a single dose, without boosters, because the PZP antigens are encapsulated within liposomes (multi-layered, submicroscopic vesicles), which gradually release PZP glycoproteins to antigen-presenting cells over an extended period of time. We review results from SpayVac trials in horses and other species to deepen our understanding of how the vaccine works and how it may best be applied to regulate free-ranging horse populations at AML. We examine 3 studies in horses, which used diff erent SpayVac formulations and delivery methods, to learn more about the relationship between antibody titers and contraceptive effi cacy, as well as potential mechanisms of action (e.g., preferential stimulation of IgG4/7 antibody isotypes). Additional research to explore possible eff ects of injection site location, antigen purity, role of PZP antibodies, and diff erent formulations (e.g., dose, adjuvant) is needed for effi cacious application to free-ranging herds. [ABSTRACT FROM AUTHOR]

Our understanding of the spatial ecology of feral horses (Equus ferus caballus) and burros (E. asinus) in the United States is limited. Robust location data are needed to better understand the permeability of Bureau of Land Management Herd Management Area boundaries, relative to feral horse movement patterns and home ranges. To increase our understanding of feral horse movement, in February to March 2017, we deployed global positioning system (GPS) collars on 14 females .5 years old that were captured in the Adobe Town Herd Management Area (ATHMA) of southcentral Wyoming, USA. Herein, we report initial results from movement data collected during summer (May 15 to September 15) 2017 for 9 horses. We limited our focus to these 9 horses because we received at least 2 months of continuous GPS location data from them during summer 2017. Feral horse daily movement distances averaged 9.0 km (SE = 0.3), and mean summer total home range size was 40.4 km2 (SE = 6.7). Of GPS location fi xes obtained, 44.9% were outside ATHMA and 10.8% were on private land. Our results highlight the types of data that GPS collars can provide and illustrate the diffi culties of managing free-roaming species such as horses and burros on landscapes with heterogeneous sociopolitical patterns. Expanded use of such technology on feral horses and burros in the United States will yield greater insight on spatial complexities constraining management. [ABSTRACT FROM AUTHOR]

Free-ranging or feral horses (Equus ferus caballus) were important to the livelihood of First Nations and indigenous communities in Canada. The early inhabitants of the boreal region of British Columbia (BC) capitalized on naturally occurring wildfi res and anthropogenic burning to provide forage for free-ranging horses and manage habitat for wildlife. This form of pyric herbivory, or grazing driven by fi re via the attraction to the palatable vegetation in recently burned areas, is an evolutionary disturbance process that occurs globally. However, its application to manage forage availability for free-ranging horses has not been studied in northern Canada. Across Canada, there are varying levels of governance for feral and free-ranging horses depending on the provincial jurisdiction and associated legislation. The BC Range Act (Act) allows range tenure holders to free-range horses that they own for commercial operations on Crown land. Big-game guide outfi tters as range tenure holders are provided grazing licences or grazing permits under the Act with an approved range use plan. Guide outfi tters and other range tenure holders have incorporated fi re ecology as part of their rangeland management in mountainous portions of the boreal forest of northeastern BC to promote mosaics of vegetation height and species composition across the landscape to meet nutritional requirements of their free-ranging horses. Using resource selection function models, we evaluated the infl uence of pyric herbivory on boreal vegetation and use by horse herds occupying 4 distinct landscapes. We found that horses preferentially selected recently burned areas and areas that burned more frequently when they were available. We also found that horses avoided steep slopes and forest cover types. Fire and the ecological processes associated with it, including pyric herbivory, are important considerations when managing boreal rangelands in northeastern BC. Because historical fi re regimes of the boreal region of Canada diff er from the arid regions of the United States inhabited by feral horses, the role of pyric herbivory in altering horse distributions in the United States is limited. [ABSTRACT FROM AUTHOR]

Since 1959, the U.S. Congress has legislated the treatment and management of wild horses (Equus ferus caballus) and burros (E. asinus; WHB). While the legislation has ensured WHB a place as western rangeland icons, subsequent congressional actions, in response to public lobbying, have limited federal managers' ability to manage WHB populations under the U.S. public land multiple-use doctrine. Federal land managers tasked with managing for multiple and competing interests on public lands of the western United States must not only consider WHB habitat requirements, but also wildlife species diversity and livestock grazing. Developing multiple-use management strategies while fulfi lling other mandates will require balancing rather than maximizing a single resource use or user. Grazing by wild and domestic animals can modify plant community composition and structure, and overabundant populations negatively impact rangeland-watershed function and wildlife habitats. Negative eff ects on wildlife may include avoidance of water sources by wildlife, forage loss and altered plant communities, altered bird communities, and impacts to soils and insects. Eff ective management for riparian and rangeland health includes managing both the abundance and the distribution of large grazers. Unless large grazers (including WHB) are managed, range condition and wildlife habitat are at risk. While livestock can be moved and removed, and big game can be hunted, the management and removal of WHB populations continues to face strong public opposition. The management of WHB under the federal land multiple-use doctrine will require implementing innovative, diverse, and tough management strategies founded in the biological and social sciences. This special issue of Human-Wildlife Interactions explores these issues in depth. This paper frames the context in which WHB management must be achieved under the U.S. public land multiple-use doctrine. [ABSTRACT FROM AUTHOR]

The Wild Free-Roaming Horses and Burros Act (WFRHBA) of 1971 established all "unbranded or unclaimed" equids on U.S. public lands as "living symbols of the historic and pioneer spirit of the West." Today, >72,000 feral horses (Equus ferus caballus) and burros (E. asinus; WHB) live on western U.S. public rangelands. The number of WHBs exceeds the Bureau of Land Management's maximum Appropriate Management Level (AML) of 26,715 by a factor of approximately 2.7 and has nearly doubled from 2007-2015. The AML was set to balance WHB numbers with rangeland health and support other uses such as wildlife habitat and livestock grazing. Thus, public land management agencies must manage WHB under the multiple-use context. This becomes more problematic when WHB populations go largely unmanaged and excessive equid grazing negatively impacts rangeland vegetation, native wildlife, and livestock forage. In addition, approximately 46,000 WHBs exist in off -range holding facilities, further straining federal budgets. Contemporary management actions are being constrained by: (1) litigation that has stymied federal government WFRHBA enforcement eff orts, (2) public emotional concerns that lack reconciliation with the current situation, and (3) increasing complexity in the laws and subsequent amendments shaping WHB management policy. Collectively, these factors impede the implementation of concrete solutions to restore AML. Consequently, stakeholders are increasing polarized over how WHBs are or should be managed. While the ecological and animal health and welfare implications of unmanaged WHB populations are somewhat understood, publicly acceptable strategies to maintain healthy populations, healthy and functioning rangelands, and multiple uses that sustain wildlife and local communities remain unresolved. [ABSTRACT FROM AUTHOR]

The number of feral horses (Equus ferus caballus) in the world has been estimated at 1.5-2 million, of which 5,000-10,000 occur in Argentina. Feral horses are considered an invasive alien species in Argentina, and as such, create a problem for biodiversity conservation. Only the population in Parque Provincial Ernesto Tornquist, Buenos Aires province, has been managed. In this paper, I discuss the confl icts between feral horse advocates, government authorities, and researchers that occurred after management actions were implemented and identify some factors that contributed to the confl ict in positive and negative manners as well as some confusing concepts and ideas. I also summarize the studies that have been completed to describe this feral horse population demography and impact on biodiversity in Argentina. Lastly, I elaborate on the challenges impeding the future management of feral horses in Argentina. [ABSTRACT FROM AUTHOR]

Porcine zona pellucida (PZP) immunocontraception was developed to provide a more humane, eff ective, and inexpensive method of population regulation for wildlife species. It has been used to regulate populations of several species including white tailed deer (Odocoileus virginianus), elk (Cervus elaphus), black bear (Ursus americanus), and the feral horse (Equus ferus caballus) with varying levels of success. Early studies on Assateague Island National Seashore, Maryland, USA, suggested PZP was as an ideal form of fertility control because it reduced the likelihood of conception to <10%, could be delivered remotely, was thought to be reversible, lacked debilitating physiological side eff ects, could not pass through the food chain, and showed minimal eff ects to social behaviors in a closed population of feral horses. However, research on Shackleford Banks, North Carolina, USA and on 3 western populations located in Little Brook Cliff s (Grand Junction, Colorado, USA), McCollough Peaks (east of Cody, Wyoming, USA), and the Pryor Mountains (Lovell, Wyoming, USA) has revealed behavioral and physiological side eff ects of long-term PZP use. When compared to untreated mares (those that have never received treatment), treated mares demonstrated decreased fi delity to the band stallion, increased and prolonged reproductive behavior, and an increased likelihood of extending reproductive cycling into the nonbreeding season. These eff ects were more pronounced in animals receiving more total and/or consecutive contraception treatments and can persist even after several years of treatment cessation. Finally, new data indicate that these changes to previously treated mares can aff ect the behavior and stress physiology of their band stallions, demonstrating the potential for the contraception of individuals to have population-level eff ects. These results are important to consider if we are to achieve both the eff ective management of feral horse populations in addition to the maintenance of their overall health and well-being. [ABSTRACT FROM AUTHOR]