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Worldwide, coastal wetlands are threatened by disrupted hydrology, urbanization, and sea-level rise. In southwest Florida, coastal wetlands include tidal creeks and coastal ponds, which are the primary habitats used by juvenile Tarpon, Megalops atlanticus, an important sport fish. Coastal ponds can occur near uplands and are ephemerally connected to the open estuary, creating conditions of variable dissolved oxygen and salinity. Juveniles can tolerate wide-ranging abiotic conditions, but little is known about how they egress from their remote nursery habitats, which often requires them to cross > 1 km of mangrove forest to reach the open estuary. The objective of this study was to (1) compare Tarpon body condition among ponds close to the open estuary versus those ponds farther away on the Cape Haze peninsula of Charlotte Harbor, Florida, and (2) using acoustic telemetry determine what factors contribute to Tarpon emigration from the ponds to open estuarine waters. We tested the hypothesis that distinct groups of Tarpon occur in isolated ponds, leading to variation in fish length and body condition, and that opportunities for emigration from these ponds hinge on high water events. No pond stood out as having Tarpon of low body condition. Factors contributing to increased probabilities of Tarpon emigration were low barometric pressure, high-water level, and Tarpon body length. Tarpon emigrated from ponds near tidal creeks during summer king tides, while tropical cyclone conditions were needed to allow for movement from ponds farther in the landscape. The juvenile Tarpon were later detected at the mouths of large rivers 30 km up-estuary. The characterizations of water levels and event criteria needed for successful Tarpon nurseries should aid in habitat conservation and the creation of Tarpon nursery habitat in restoration designs. [ABSTRACT FROM AUTHOR]

When thick wet snow covers unfrozen ground at the beginning of winter, herders fear the development of a hard, icy bottom snow layer and the appearance of noxious moulds (microfungi) in semi-domesticated reindeer pastures. Such winter onsets were experienced in 2019 and 2021 in the reindeer herding area of Finland, after which significant reindeer losses, along with collapses in calf production and slaughter animals, were encountered. We studied the development of weather and snow conditions in the late autumn and early winter of 2021–2022 and measured snow conditions in March 2022 in 11 reindeer cooperatives. We also collected samples from reindeer winter forage plants for mycotoxin analysis. We found that the weather and snow conditions during the late autumn and early winter of 2021 caused the formation of a hard, icy bottom snow layer and the development of mycotoxins in pastures. Alternariol (AOH) and alternariol monomethyl ether (AME), produced by Alternaria spp., were found in all 33 samples (104–2562, 61–808 µg/kg DM) and zearalenone (ZEN) by Fusarium spp. in 16 samples (14–206 µg/kg). Certain significant correlations in the concentrations of mycotoxins with snow conditions and ground surface temperatures were found. We assume that besides difficult grazing conditions in the winters of 2019–2020 and 2021–2022, the presence of mycotoxins in pastures has contributed to reindeer losses and reduced the body condition, health, and reproduction of reindeer. As onsets of winters become warmer and rainier, the risk of similar pasture conditions in reindeer herding may increase. [ABSTRACT FROM AUTHOR]

Body condition is a measure of an animal's energy reserves relative to its body structure that provides important information about individual- and population-level health. Monitoring the body condition of free-ranging cetaceans has historically been difficult, but in recent years, the unmanned aerial system (UAS, or "drone") has facilitated noninvasive ways of estimating the cetacean body condition. The Charleston Estuarine System (CES) includes the estuarine and coastal ecosystems surrounding Charleston, South Carolina, and is utilized by Tamanend's bottlenose dolphins (Tursiops erebennus) throughout the year. The main goals of this study were (1) to test if UASs are suitable for monitoring body condition of dolphins in an estuarine environment, and (2) to determine if site, season, and age class influence the body condition of dolphins in the CES. Land-based UAS surveys were conducted at four sites throughout the CES between September 2022 and May 2023. The body condition of each dolphin was evaluated using images of the individual positioned flat with a straight body at the surface, and a linear mixed effects model was constructed to determine which effects were associated with significant differences in dolphin body condition. After filtering images for quality, 428 images of 174 unique dolphins were included in the final analysis, with repeated body condition estimates of 24 dolphins from multiple seasons. Both season and age class were significant predictors of dolphin body condition, but site was not. In addition, individual dolphins were catalogued in a Drone Dolphin ID database, which allowed some dolphins' unique body condition changes to be tracked over time. These findings provide an important baseline for dolphin body condition in the CES that can be built upon in future studies to better understand how body condition changes in response to environmental and anthropogenic stressors or for different age classes. [ABSTRACT FROM AUTHOR]

Patterns of feeding and growth of Atlantic salmon Salmo salar L. in the marine environment are critical to understanding how observed declines in recruitment may reflect warming or other oceanic drivers. The isotopic composition of scales can provide insight into differences in marine feeding location and possibly temperature regime. The authors used archived scale samples to measure δ13C and δ15N deposited in the scales of one sea‐winter (1SW) salmon during their last season of growth at sea before they returned to five Irish rivers. δ13C values were related statistically to observed salmon body condition (Fulton's K), and fish with higher δ13C values tended to show significantly better condition. In contrast, δ15N values were negatively related to body condition. There was no important effect on condition of length at smolt migration, and the effect of duration of marine residence varied among rivers. It is likely that δ13C values partly reflected ambient ocean temperature and recent marine feeding environment before return migration, such that the observed relationship between higher δ13C values and increased body condition may express an advantage for adult fish feeding in warmer, potentially closer, waters. If greater body condition influences fitness, then a changing temperature regime in the Northeast Atlantic may drive shifts in salmon survival and reproduction. This study provides evidence that there is spatial and trophic variation at sea between salmon from rivers of origin that are located relatively close to each other, with potential consequences for body condition and, consequently, fitness and life history; this suggests that salmon populations from geographically proximate rivers within regions may exhibit differential responses to ocean‐scale climatic changes across the Northeast Atlantic. [ABSTRACT FROM AUTHOR]

Bird body mass is often used as an index of body condition and fluctuates throughout the year in response to environmental conditions and avian life‐history events. We examined the body mass of 59,572 ducks representing 13 species (7 dabbling duck species and 6 diving duck species) harvested within the 3 regions of the Central Valley in California, USA (Sacramento Valley, Suisun Marsh, San Joaquin Valley). Data collection occurred in winter during 5 hunting seasons (2014–2015, 2015–2016, 2017–2018, 2018–2019, 2019–2020). For all species, age, and sex classes, the body mass of dabbling ducks varied temporally and was lowest at the end of the hunting season in late January, declining from the beginning of the hunting season in mid‐October (northern pintail [Anas acuta]: −11.4% to −20.4%; northern shoveler [Spatula clypeata]: −3.5% to −17.3%; cinnamon teal [Anas cyanoptera]: −5.0% to −17.1%; American wigeon [Mareca americana]: −6.9% to −12.2%; American green‐winged teal [Anas carolinensis]: −5.9% to −11.9%; mallard [Anas platyrhynchos]: −1.8% to −9.6%; gadwall [Mareca strepera]: −2.2% to −8.4%). As expected, adults (after hatch‐year) were heavier than immature (hatch‐year) birds (within males: 0.6–8.6%; within females: 0.1–6.6%) and males were heavier than females (within adults: 3.1–38.6%; within immatures: 5.4–33.5%) at the end of the hunting season in all species. Within dabbling duck species, body masses did not differ among regions at the beginning of the hunting season but were heavier in the Sacramento Valley (0.5–14.4%) than other areas by the end of the hunting season. In contrast, body masses of diving ducks did not vary substantially during the hunting season or among regions. Diving ducks demonstrated inconsistent changes in mass from the beginning to the end of the season (lesser scaup [Aythya affinis]: 3.4% to 12.3%; canvasback [Aythya valisineria]: 5.1% to 6.1%; bufflehead [Bucephala albeola]: −3.2% to 1.6%; ring‐necked duck [Aythya collaris]: −4.9% to 2.6%; common goldeneye [Bucephala clangula]: −3.2% to −2.4%; ruddy duck [Oxyura jamaicensis]: −16.5% to 5.5%). The substantial temporal and spatial differences in dabbling duck body masses suggest that habitat quality (as measured by caloric value of the available food) or quantity may decline during winter and varies regionally within California's Central Valley. [ABSTRACT FROM AUTHOR]

Body composition is an important parameter in diving animals intermittently fasting on land, such as southern elephant seals, as it is known to impact their time of departure at sea, swimming effort, foraging success, and survival. Deuterium labeled water is commonly used to assess total body water, but a precise indication of equilibration time in this species and reliable sample storage are lacking. We injected newly weaned southern elephant seal female pups with deuterium-labeled water. We thereafter blood sampled the seals several times to assess the equilibration time and body composition. We implemented two storage methods, flame-sealed capillaries and frozen serums stored at − 20 °C in a gas freezer. The frozen serums method was reliable as capillaries and safer to bring undamaged samples from the field. This method of determining body composition in wild animals is reliable and easily applicable for isolated and difficult-to-access fieldwork. [ABSTRACT FROM AUTHOR]

Despite the increased frequency with which wildfire smoke now blankets portions of world, the effects of smoke on wildlife, and birds in particular, are largely unknown. We used 2 decades of banding data from the San Francisco Bay Bird Observatory to investigate how fine particulate matter (PM2.5)—a major component and indicator of wildfire smoke—influenced capture rates and body condition of 21 passerine or near-passerine bird species. Across all study species, we found a negative effect of acute PM2.5 exposure and a positive effect of chronic PM2.5 exposure on avian capture rates. Together, these findings are indicative of decreased bird activity or local site removal during acute periods of wildfire smoke, but increased activity or site colonization under chronic smoke conditions. Importantly, we also observed a negative relationship between chronic PM2.5 exposure and body mass change in individuals with multiple captures per season. Our results indicate that wildfire smoke likely influences the health and behavior of birds, ultimately contributing to a shift in activity and body condition, with differential short-term versus long-term impacts. Although more research is needed on the mechanisms driving these observed changes in bird health and behavior, as well as validation of these relationships in more areas, our results suggest that wildfire smoke is a potentially frequent large-scale environmental stressor to birds that deserves increasing attention and recognition. [ABSTRACT FROM AUTHOR]

Myctophids are one of the most diverse and abundant fish families in the mesopelagic zone, making them a key component in the marine pelagic community. In the North Atlantic, Benthosema glaciale (glacier lantern fish) is considered the most abundant myctophid north of 35° N, yet some regions within its extensive range lack information on its basic biological parameters. We investigated the growth and described the distribution of B. glaciale in Icelandic waters, including the southern continental shelf, Iceland Basin, and Irminger Sea. Length distribution, growth, relative body condition, age, and otolith‐fish size relationships were analyzed from samples collected opportunistically with pelagic trawls during the International Ecosystem Summer Survey in the Nordic Seas (IESSNS) in July 2020. In total, 1374 individuals were caught, and only a subset of 225 were measured fresh at sea and 89 were frozen and dissected on land. Total lengths of fresh fish ranged from 38 to 85 mm, while dissected individuals ranged from 40 to 74 mm and were 2 to 6 years old. Located over the Reykjanes Ridge in the Iceland Basin region, individuals had a significantly higher mean standard length and mean age, and a lower mean body condition. We reported length–weight relationships for both fresh and frozen samples, indicating evidence that preserving of the specimens through freezing affected relationships. The von Bertalanffy growth curve was calculated along with significant otolith‐fish size relationships where r2 values ranged between 0.87 and 0.92. Our research highlights the importance of cross‐regional studies and provides baseline biology for B. glaciale in Icelandic waters, specifically in the southern continental slope and Reykjanes Ridge. [ABSTRACT FROM AUTHOR]

Monitoring the nutritional health of cetaceans has become increasingly important in a changing environment, where multiple stressors impact animals. Particularly for those species that require consumption of energy‐dense prey, such as the common dolphin. Thus far, no uniform measure for monitoring body condition has been recommended across cetaceans, and species‐specific measures may need to be developed if employed as a population condition indicator under Descriptor 1 of the Marine Strategy Framework Directive. Here, nine morphometric body condition indices were applied to long‐term common dolphin stranding data sets originating from Ireland and the UK. We report a recent decline in the nutritional health of common dolphins in the Celtic Seas ecoregion comparing animals from 2017 to 2019 to animals from 1990 to 2006, with an increase in cases of animals dying due to starvation. Using ordinal regression trees, ventral blubber thickness (VBT) was identified as the most important index to predict nutritional status, defined at necropsy, followed by the scaled mass index (SMI). Using generalised linear models, both the VBT and SMI indices differentiated individuals that died from chronic and acute causes of death (i.e., bycatch), where animals in chronic conditions had significantly thinner VBT and lower SMI. Both significant temporal and seasonal patterns in VBT were identified, with poorer body conditions observed during the autumn and better body conditions observed during the spring, as well as an overall decline detected in VBT during the study period. While VBT was positively correlated with total body length, SMI showed the opposite trend. The VBT index is recommended for monitoring nutritional health within the species when total body length and season are considered. Further research is needed to understand the underlying causes for the observed decline, including shifts in prey availability and/or quality, to inform targeted conservation management strategies. [ABSTRACT FROM AUTHOR]

The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. Bile acids (BA) play a crucial role not only in lipid digestion but also in the regulation of overall energy homeostasis, including glucose and lipid metabolism. The aim of this study was to investigate BA profiles and mRNA expression of BA-related genes in the liver of high versus normal body condition in dairy cows. We hypothesized that body condition and the transition from gestation to lactation affect hepatic BA concentrations as well as the mRNA abundance of BA-related receptors, regulatory enzymes, and transporters. Therefore, we analyzed BA in the liver as well as the mRNA abundance of BA-related synthesizing enzymes, transporters, and receptors in the liver during the transition period in cows with different body conditions around calving. In a previously established animal model, 38 German Holstein cows were divided into groups with high body condition score (HBCS; n = 19) or normal body condition score (NBCS; n = 19) based on BCS and backfat thickness (BFT). Cows were fed diets aimed at achieving the targeted differences in BCS and BFT (NBCS: BCS <3.5, BFT <1.2 cm; HBCS: BCS >3.75, BFT >1.4 cm) until they were dried off at wk 7 before parturition. Both groups were fed identical diets during the dry period and subsequent lactation. Liver biopsies were taken at wk −7, 1, 3, and 12 relative to parturition. For BA measurement, a targeted metabolomics approach with liquid chromatography electrospray ionization MS/MS was used to analyze BA in the liver. The mRNA abundance of targeted genes related to BA synthesizing enzymes, transporters, and receptors in the liver was analyzed using microfluidic quantitative PCR. In total, we could detect 14 BA in the liver: 6 primary and 8 secondary BA, with glycocholic acid (GCA) being the most abundant one. The increase of glycine-conjugated BA after parturition, in parallel to increasing serum glycine concentrations may originate from an enhanced mobilization of muscle protein to meet the high nutritional requirements in early lactating cows. Higher DMI in NBCS cows compared with HBCS cows was associated with higher liver BA concentrations such as GCA, deoxycholic acid, and cholic acid. The mRNA abundance of BA-related enzymes measured herein suggests the dominance of the alternative signaling pathway in the liver of HBCS cows. Overall, BA profiles and BA metabolism in the liver depend on both, the body condition and lactation-induced effects in periparturient dairy cows. [ABSTRACT FROM AUTHOR]

Changes in buoyancy of marine mammals can be used to infer environmental changes. In multiple seal species, how "fast" an animal sinks reveals body condition changes through shifts in buoyancy as the ratio between lean and lipid tissue changes. However, quantifying similar at‐sea changes in Weddell seals (Leptonychotes weddellii) has remained unexplored. Here, we present a method of inferring buoyancy of Weddell seals by monitoring descent rates from 4‐s time‐depth data, to reveal in situ insight of their life cycle. We defined a Buoyancy Indicator Segment (BIS) as the descent rate of a dive segment created with the broken‐stick method that was systematically filtered to only include characteristic nonstroking and directed travel segments while excluding lung buoyancy biases. We found that BISs predicted body condition changes in Weddell seals, being a function of dive duration, mean depth, and time‐of‐year. Descent rates quickened with troughs in early April due to postmolt muscle recovery, early July due to winter conditions, and early September possibly due to pregnancy. Each trough was followed by weight gain, with slowing descent rates reaching peaks in late May, early August, and late October. This new approach showed that determining at‐sea condition is possible for Weddell seals, deriving a powerful species and environmental monitoring tool. [ABSTRACT FROM AUTHOR]

Monitoring body length and body condition of individuals helps determine overall population health and assess adaptation to environmental changes. Aerial photogrammetry from drone‐based videos is a valuable method for obtaining body length and body condition measurements of cetaceans. However, the laborious manual processing of drone‐based videos to select frames to measure animals ultimately delays assessment of population health and hinders conservation actions. Here, we apply deep learning methods to expedite the processing of drone‐based videos to improve efficiency of obtaining important morphological measurements of whales. We develop two user‐friendly models to automatically (1) detect and output frames containing whales from drone‐based videos ("DeteX") and (2) extract body length and body condition measurements from input frames ("XtraX"). We use drone‐based videos of gray whales to compare manual versus automated measurements (n = 86). Our results show automated methods reduced processing times by one‐ninth, while achieving similar accuracy as manual measurements (mean coefficient of variation <5%). We also demonstrate how these methods are adaptable to other species and identify remaining challenges to help further improve automated measurements in the future. Importantly, these tools greatly speed up obtaining key morphological data while maintaining accuracy, which is critical for effectively monitoring population health. [ABSTRACT FROM AUTHOR]

Color polymorphisms in poison frogs have intrigued evolutionary ecologists, as understanding the mechanisms that sustain them is of great interest. Temporal variation in selection is considered crucial for maintaining color polymorphism, and monitoring aposematic signals provides valuable insights into such temporal dynamics. We conducted a six-year study on red-belly toads, Melanophryniscus rubriventris, analyzing color patterns and body size variation across five reproductive seasons. Our findings show stable color morph ratios over time, with no discernible differences between sexes and no interdependence between dorsal and ventral patterns. Notably, darker morphs, mostly melanic, comprised only about 25% of the population, contrasting with the higher frequency of conspicuous aposematic combinations. Intermediate morphs were more prevalent, while the most extreme conspicuous dorsal pattern was rare. Regarding body size, females were significantly larger and in better body condition than males. We observed a significant decrease in snout-vent length for males between 2021 and 2022, while females showed a significant increase between 2020 and 2022. Interestingly, there was a phenotypic association between color patterns and body size, with males exhibiting black bellies having smaller snout-vent lengths compared to those with other ventral patterns, particularly red bellies. Our study suggests that dorsal and ventral color patterns may respond differently to selection. The stability of color patterns within the population could be upheld through complex interactions involving stabilizing and sexual selection. We emphasize the importance of long-term studies and recommend that future research considers reproductive ecology and individual behavioral decisions in this polymorphic aposematic species. By incorporating these aspects, we can gain a more comprehensive understanding of the mechanisms driving phenotypic variation. [ABSTRACT FROM AUTHOR]

Background/Objectives: The negative energy balance activaties of spontaneous lipolysis. This may promotes inflammation within the adipose tissue. The aim of the study was to explain the development of inflammation during increased lactogenesis. It was hypothesized that lipolysis contributes synthesis of interleukin-6 and plasminogen. Methods: The study was in production conditions carried out using Holstein-Friesian cows. The period studied covered time of early lactation. Results: Up to the peak of lactation, milk yield strongly influenced the rate of loss of body condition. This had an impact on with the intensity of the release of the fatty acids. In both cases this relationships strengthened to the peak of production. Oobserved tendencies towards a decrease in the concentration of glucose and an increase in that of leptin. Loss of the body condition and the release of NEFA were were influencing to affect the blood concentrations of interleukin-6 and plasminogen. We have shown that IL-6 has a relatively strong correlation with the NEFA. They correlate with IL-6 independently of EB influence. This may suggest independent associations between these variables, which could potentially be applied in practice. Conclusions: The NEFA release in the long term can increase the inflammatory response within adipose tissue and can intensify the release of interleukin-6 and plasminogen. It is likely that in the initial stage of lactogenesis, the inflammatory process developing within adipose tissue is physiologically justified. Our results can provide background to this little-described area of research. [ABSTRACT FROM AUTHOR]

ABSTRACT: Bile acids (BA) play a crucial role not only in lipid digestion but also in the regulation of overall energy homeostasis, including glucose and lipid metabolism. The aim of this study was to investigate BA profiles and mRNA expression of BA-related genes in the liver of high versus normal body condition in dairy cows. We hypothesized that body condition and the transition from gestation to lactation affect hepatic BA concentrations as well as the mRNA abundance of BA-related receptors, regulatory enzymes, and transporters. Therefore, we analyzed BA in the liver as well as the mRNA abundance of BA-related synthesizing enzymes, transporters, and receptors in the liver during the transition period in cows with different body conditions around calving. In a previously established animal model, 38 German Holstein cows were divided into groups with high body condition score (HBCS; n = 19) or normal body condition score (NBCS; n = 19) based on BCS and backfat thickness (BFT). Cows were fed diets aimed at achieving the targeted differences in BCS and BFT (NBCS: BCS 3.75, BFT >1.4 cm) until they were dried off at wk 7 before parturition. Both groups were fed identical diets during the dry period and subsequent lactation. Liver biopsies were taken at wk −7, 1, 3, and 12 relative to parturition. For BA measurement, a targeted metabolomics approach with liquid chromatography electrospray ionization MS/MS was used to analyze BA in the liver. The mRNA abundance of targeted genes related to BA synthesizing enzymes, transporters, and receptors in the liver was analyzed using microfluidic quantitative PCR. In total, we could detect 14 BA in the liver: 6 primary and 8 secondary BA, with glycocholic acid (GCA) being the most abundant one. The increase of glycine-conjugated BA after parturition, in parallel to increasing serum glycine concentrations may originate from an enhanced mobilization of muscle protein to meet the high nutritional requirements in early lactating cows. Higher DMI in NBCS cows compared with HBCS cows was associated with higher liver BA concentrations such as GCA, deoxycholic acid, and cholic acid. The mRNA abundance of BA-related enzymes measured herein suggests the dominance of the alternative signaling pathway in the liver of HBCS cows. Overall, BA profiles and BA metabolism in the liver depend on both, the body condition and lactation-induced effects in periparturient dairy cows.

Abstract Parasites negatively affect the fitness of ungulate hosts directly, and in wild ungulates, these effects may be synzootic with other stressors, such as limited nutritional resources. In the Arctic, muskoxen (Ovibos moschatus) occur in a highly seasonal environment and must rely on finite energetic resources for survival and productivity. We investigated the costs of gastrointestinal nematodes on the body condition and reproductive status of 141 muskoxen, on Banks Island, Canada, when the population was at a peak in numbers and density. Using a Partial Least Squares Path Modelling approach, we found that high adult nematode abundance was associated with lower body condition, and high parasite abundance was associated with female reproduction including the indirect effect through on body condition (n = 87). These findings suggest that individuals prioritize energetic reserves for reproduction over parasite defence. In fall 2003, a severe icing event that restricted access to forage was associated with high overwinter mortality of muskoxen and a population crash. Through direct and indirect costs of parasite infection on body condition and reproduction, the high abundance of parasites may have contributed to the effects of this extreme weather event. Understanding the mechanisms in which parasites impact fitness can help explain the ecological drivers of ungulate populations and predict the interactions between the environment and populations.

Abstract Urban areas, i.e. dense housing and reduced green spaces, can significantly impact avian health, through altering land use and increasing biotic and abiotic stress. This study assessed the association of urbanization on haemosporidian infections, vectors, immune response, and body condition in Parus major nestlings, across four classes of urbanization along an urban-to-rural gradient in Vienna, Austria. Contrary to our expectations, vector abundance remained consistent across the gradient, while an increase in leukocyte count is positively associated with total parasite intensity. We found that nestlings in more urbanized areas exhibited higher parasite intensity and altered immune response, as evidenced by variations in the heterophil to lymphocyte ratio and leukocyte counts. Culicidae female vectors were associated with nestlings’ total parasites, scaled mass index, and industrial units. Nestlings in highly developed areas had higher infection rates than those in forests, suggesting increased exposure to infections. However, there was no clear relationship between total female vectors and total parasites. The level of urbanization negatively affected nestling body condition, with a decrease in fat deposits from forested to highly urbanized areas. Our findings highlight the complex interplay between urbanization, vector-borne parasite transmission, and host immune response, emphasizing the need for comprehensive urban planning to improve wildlife health and guarantee ecosystem functioning. Understanding how urbanization affects bird immunity and parasite infections is critical for adapting urban landscapes for wildlife health and ecosystem integrity.

The gut microbiota-immune-brain axis is a feedback network which influences diverse physiological processes and plays a pivotal role in overall health and wellbeing. Although research in humans and laboratory mice has shed light into the associations and mechanisms governing this communication network, evidence of such interactions in wild, especially in young animals, is lacking. We therefore investigated these interactions during early development in a population of common buzzards (Buteo buteo) and their effects on individual condition. In a longitudinal study, we used a multi-marker approach to establish potential links between the bacterial and eukaryotic gut microbiota, a panel of immune assays and feather corticosterone measurements as a proxy for long-term stress. Using Bayesian structural equation modeling, we found no support for feedback between gut microbial diversity and immune or stress parameters. However, we did find strong relationships in the feedback network. Immunity was negatively correlated with corticosterone levels, and microbial diversity was positively associated with nestling body condition. Furthermore, corticosterone levels and eukaryotic microbiota diversity decreased with age while immune activity increased. The absence of conclusive support for the microbiota-immune-brain axis in common buzzard nestlings, coupled with the evidence for stressmediated immunosuppression, suggests a dominating role of stress-dominated maturation of the immune system during early development. Confounding factors inherent to wild systems and developing animals might override associations known from adult laboratory model subjects. The positive association between microbial diversity and body condition indicates the potential health benefits of possessing a diverse and stable microbiota. [ABSTRACT FROM AUTHOR]

Wildlife contend with seasonal fluctuations in resource availability and have adapted survival and reproductive strategies to overcome resource limitations. Many northern ungulates are adapted to a dynamic nutritional landscape and rely on somatic reserves accumulated during the short growing season. Moose (Alces alces) populations in the boreal forest respond to variation in their nutritional landscapes that quickly change after wildland fires. We tested associations between somatic energy reserves of female moose and a suite of factors relevant to energy demands and nutrient availability after landscape scale wildland fires on the Kenai Peninsula, Alaska. From 2015-2022, we immobilized 97 individual, adult moose (n=163 early winter; n=98 late winter) and collected over 223,000 GPS locations. We evaluated if somatic energy reserves of cow moose were influenced by endogenous or exogenous energy demands, or access to moose forage to accumulate energy reserves. Cows that gave birth and lost their neonate(s) early in the summer had more early winter body fat (14.39% ± 0.24SE) compared with cows that gave birth and the neonate survived to 4-months-old (10.59% ± 0.34SE). Body fat measured in early winter was positively correlated with home ranges of cows during summer with a higher percent cover of aspen forage. Late winter body fat of cow moose was negatively correlated with home ranges with higher percent cover of aspen forage, but positively correlated with home ranges with higher percent cover of willows and shoulder season forages. Our results highlight that a suite of plant species and seral states is needed across the landscape for moose to accumulate and moderate the loss of somatic energy reserves over the year. Furthermore, our results emphasize the importance of shoulder season forages for moose when snow depth is low. Managing the nutritional landscape of the boreal forest through interagency wildland fire management could create a mosaic of seral states that enhances moose forage, while reducing wildland fire hazards along the wildland urban interface and providing ecosystem services. [ABSTRACT FROM AUTHOR]

In Amazonian streams, damming caused by road construction changes the system's hydrological dynamics and biological communities. We tested whether the degree of specialization in fish (Bryconops giacopinii) individuals is higher in pristine stream environments with intact ecological conditions than in streams dammed due to the construction of a highway in the Amazon rainforest. To achieve this, stomach content data and stable isotopes (δ13C and δ15N) in tissues with varying isotopic incorporation rates (liver, muscle, and caudal fin) were used to assess the variation in consumption of different prey over time. The indices within‐individual component (WIC)/total niche width (TNW) and individual specialization were employed to compare the degree of individual specialization between pristine and dammed streams. The condition factor and stomach repletion of sampled individuals were used to infer the intensity of intraspecific competition in the investigated streams. The species B. giacopinii, typically considered a trophic generalist, has been shown to be, in fact, a heterogeneous collection of specialist and generalist individuals. Contrary to our expectations, a higher degree of individual specialization was detected in streams dammed by the highway. In dammed streams, where intraspecific competition was more intense, individuals with narrower niches exhibited poorer body conditions than those with broader niches. This suggests that individuals adopting more restricted diets may have lower fitness, indicating that individual specialization may not necessarily be beneficial for individuals. Our results support the notion that intraspecific competition is an important mechanism underlying individual specialization in natural populations. Our results suggest that environmental characteristics (e.g., resource breadth and predictability) and competition for food resources interact in complex ways to determine the degree of individual specialization in natural populations. [ABSTRACT FROM AUTHOR]

Female and male hosts may maximise their fitness by evolving different strategies to compensate for the costs of parasite infections. The resulting sexual dimorphism might be apparent in differential relationships between parasite load and body condition, potentially reflecting differences in energy allocation to anti‐parasitic defences. For example, male lacertids with high body condition may produce many offspring while being intensely parasitised. In contrast, female lacertids may show a different outcome of the trade‐offs between body condition and immunity, aiming to better protect themselves from the harm of parasites.We predicted that females would have fewer parasites than males and a lower body condition across parasitaemia levels because they would invest resources in parasite defence to mitigate the costs of infection. In contrast, the male strategy to maximise access to females would imply some level of parasite tolerance and, thus, higher parasitaemia.We analysed the relationship between the body condition of lizards and the parasitemias of Karyolysus and Schellackia, two genera of blood parasites with different phylogenetic origins, in 565 females and 899 males belonging to 10 species of the Lacertidae (Squamata). These lizards were sampled over a period of 12 years across 34 sampling sites in southwestern Europe.The results concerning the Karyolysus infections were consistent with the predictions, with males having similar body condition across parasitaemia levels even though they had higher infection intensities than females. On the other hand, females with higher levels of Karyolysus parasitaemia had lower body condition. This is consistent with the prediction that different life strategies of male and female lacertids can explain the infection patterns of Karyolysus. In contrast, the parasitaemia of Schellackia was consistently low in both male and female hosts, with no significant effect on the body condition of lizards. This suggests that lizards of both sexes maintain this parasite below a pathogenic threshold. [ABSTRACT FROM AUTHOR]

Current theory predicts that plains zebra (Equus quagga) populations should be resource‐limited. Long‐term, detailed work in the Hwange ecosystem (Zimbabwe) on zebras and all their major predators provides empirical data to test this on a population that has been at a low density for at least 2 decades and is largely naturally regulated. Information on body condition is used as an indicator of resource use, and offtakes by the three major predators are estimated from a synthesis of data on densities and diets. This information leads to rejection of the expectations for resource limitation. Zebras provide a significant part of the diets of all the main predators and are important (11%) for the most abundant of these, spotted hyaenas (Crocuta crocuta). Using conservative values, we calculate that the three main predators, hyaenas, lions (Panthera leo), and leopards (Panthera pardus), kill some 17.5% of the zebra population. Given that this estimated offtake is of the same order of magnitude as maximum population growth (22.3% per year), we conclude that this population is likely to be limited by predation. Further work is needed to better understand the mechanisms by which the greater susceptibility of juveniles to predation in ungulates contributes to population limitation. [ABSTRACT FROM AUTHOR]

We aimed to evaluate the metabolic and performance differences in primiparous Nellore cows, which became pregnant at 14 or 24-mo old. Thirty-eight cows with 202 ± 5 days of gestation were divided into two treatments according to breeding age: 14 or 24-mo. Cows were evaluated for body weight (BW), body condition score (BCS), carcass characteristics, milk yield, calves’s performance, and blood characteristics. The animals were managed in eight paddocks under continuous grazing and evaluated from 90 d before parturition until 240 d after calving. We observed an interaction between breeding age and time (P < 0.01) for cow BW. Both breeding age categories experienced BW loss during parturition, with a concurrent decrease in BCS. However, following their first calving, the BW of 24-mo cows remained stable (P > 0.05), whereas 14-mo cows exhibited a gradual recovery in BW after parturition (P < 0.05). Milk yield was greater in 24-mo animals (P < 0.01), but decreased with increasing milking days (p < 0.05) for both groups. The weight gain calves from the heifers bred at 24-mo was greater (P < 0.01), which reflected in greater BW at weaning. The beta-hydroxybutyrate (β-OHB) concentration was greater before calving and a marked decrease after parturition (P < 0.05). The 24-mo cows had greater blood β-OHB (P < 0.01) at prepartum and 30 days after calving. Blood progesterone was greater in 24-mo cows (P > 0.05). Primiparous beef cows that conceive at either 14 or 24-months of age exhibit distinct nutritional requirements and metabolic profiles. Notably, cows that conceive at 24-months of age have the advantage of weaning heavier calves and displaying a more consistent reproductive cycle following their first calving than cows that conceive at 14-months. [ABSTRACT FROM AUTHOR]

This study investigates the impact of water faecal contamination on highly threatened European brook lamprey larvae (Lampetra planeri). Water samples and the midgut contents of lampreys collected from a small lowland river upstream (site 1) and downstream from a wastewater treatment plant (WWTP) discharge (site 2) were analysed to check how the faecal microbial load of the habitat is reflected in the intestines of larval lampreys. The counts of viable mesophiles, psychrophiles, Escherichia coli and faecal streptococci as bacterial indicators of microbial (including faecal) water contamination were estimated. Microbial composition and abundance in larval midgut contents depended on the numbers of various microorganisms in the water environment. At site 2, the water was heavily microbiologically contaminated throughout the year by sewage inflow from the WWTP, and the amounts of studied bacteria were also high in the midgut of lampreys inhabiting site 2 regardless of the season. At site 1, water quality was better, and the levels of tested microbial indicators were lower in the intestines of the lampreys living there. The numbers of bacteria dependent on water temperature were growing in warmer seasons both in water and in intestines. Sewage pollution negatively influenced the condition of lampreys in site 2, where they exhibited lower body condition than in site 1. [ABSTRACT FROM AUTHOR]

Determining the effectiveness of conservation actions is a priority in conservation biology, especially in island ecosystems which can host large numbers of endemic and often threatened species. In this study, we have brought together a genetic, body condition and breeding success assessment with the aim of evaluating the viability of a newly founded population of the endangered Gran Canaria blue chaffinch (Fringilla polatzeki), the forest passerine species with the most restricted distribution in the Western Palearctic. The species occurs exclusively in the Canary pine forests (Pinus canariensis) of the island of Gran Canaria, with the Inagua nature reserve harbouring the highest number individuals. In 2010, a translocation program was initiated within the same island in the nearby pine forests of La Cumbre with the goal of establishing a viable breeding population. Genetic results revealed that La Cumbre shows genetic parameters (diversity, inbreeding, and relatedness) similar to the core source of Inagua, which contrasts with the reduced genetic diversity expected due to the small size of the newly founded population. The biometric and body condition results (wing and tarsus length, body mass, and length asymmetry of the tail feathers), together with the breeding success (nest survival and number of fledglings per successful breeding attempt), were also similar in both populations. Overall, these findings suggest that the translocation program has been successful and provide insights on the effectiveness of the actions performed. Our evaluation also delivers future avenues for the conservation planning in other upland forest endangered avian species inhabiting island ecosystems, especially those threatened by the effects of global warming. [ABSTRACT FROM AUTHOR]

The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. Besides their lipid-digestive role, bile acids (BA) influence overall energy homeostasis, such as glucose and lipid metabolism. We hypothesized that BA along with their receptors, regulatory enzymes, and transporters are present in subcutaneous adipose tissue (scAT). In addition, we hypothesized that their mRNA abundance varies with the body condition of dairy cows around calving. Therefore, we analyzed BA in serum and scAT as well as the mRNA abundance of BA-related enzymes, transporters, and receptors in scAT during the transition period in cows with different body conditions around calving. In a previously established animal model, 38 German Holstein cows were divided into either a high (HBCS; n = 19) or normal BCS (NBCS; n = 19) group based on their BCS and back-fat thickness (BFT). Cows were fed different diets to achieve the targeted differences in BCS and BFT (NBCS: BCS <3.5, BFT <1.2 cm; HBCS: BCS >3.75, BFT >1.4 cm) until dry-off at 7 wk antepartum. During the dry period and subsequent lactation, both groups were fed the same diets according to their energy demands. Using a targeted metabolomics approach via liquid chromatography-electrospray ionization-MS /MS, BA were analyzed in serum and scAT at wk −7, 1, 3, and 12 relative to parturition. In serum, 15 BA were observed: cholic acid (CA), chenodeoxycholic acid (CDCA), glycocholic acid (GCA), taurocholic acid (TCA), glycochenodeoxycholic acid (GCDCA), taurochenodeoxycholic acid, deoxycholic acid (DCA), lithocholic acid, glycodeoxycholic acid (GDCA), glycolithocholic acid, taurodeoxycholic acid, taurolithocholic acid, β-muricholic acid, tauromuricholic acid (sum of α and β), and glycoursodeoxycholic acid, whereas in scAT 7 BA were detected: CA, GCA, TCA, GCDCA, taurochenodeoxycholic acid, GDCA, and taurodeoxycholic acid. In serum and scAT samples, the primary BA CA and its conjugate GCA were predominantly detected. Increasing serum concentrations of CA, CDCA, TCA, GCA, GCDCA, DCA, and β-muricholic acid with the onset of lactation might be related to the increasing DMI after parturition. Furthermore, serum concentrations of CA, CDCA, GCA, DCA, GCDCA, TCA, lithocholic acid, and GDCA were lower in HBCS cows compared with NBCS cows, concomitant with increased lipolysis in HBCS cows. The correlation between CA in serum and scAT may point to the transport of CA across cell membranes. Overall, the findings of the present study suggest a potential role of BA in lipid metabolism depending on the body condition of periparturient dairy cows. [ABSTRACT FROM AUTHOR]

Declines in body size can be an advantageous physiological response to warming temperatures, or a result of physiological and nutritional stress. Either way, studies often assume that these climate‐induced trait changes have important implications for fitness and demography. We leveraged almost three decades of capture‐mark‐recapture data of 51 bird species in Panama to examine if body size has changed through time, how sensitive body size is to changes in weather, and if body size impacts population demography. We evaluated two metrics of body size, structural size (wing length), and body condition (residual body mass). Over the study, wing length changed in varying directions for 88% of species (23 decrease, 22 increase), but the effects were weak, and change was only significant for two species. Conversely, body condition declined for 88% of species (45), effects were stronger, and that change was significant for 22% of species (11). This suggests that nutritional stress is likely the cause of changes in body size, not an adaptive response to warming. Precipitation metrics impacted body condition across three of our four feeding guilds, while wing length was only impacted by weather metrics for two guilds. This suggests that body condition is more sensitive to change in weather metrics compared to wing length. Lastly, we found that the impact of changes in body size on survival and recruitment was variable across species, but these relationships were in the opposite direction, ultimately resulting in no change in population growth for all but one species. Thus, while different stages (adult survival and recruitment) of populations may be impacted by body size, populations appear to be buffered from changes. The lack of an effect on population growth rate suggests that populations may be more resilient to changes in body size, with implications for population persistence under expected climate change. [ABSTRACT FROM AUTHOR]

Nutrient requirements for lactation often lead to a negative energy balance accompanied by reduced body condition and fertility in cattle. A previous study identified an increased abundance of serum metabolites associated with tissue mobilization and reactive oxygen species (ROS) generation in postpartum beef cows with a thin versus moderate body condition. No studies, however, have measured ROS levels in the serum and follicular fluid of postpartum beef cows for comparison with body condition. We hypothesized that beef cows with a thin body condition would have elevated levels of ROS, as indicated by hydrogen peroxide (H2O2), in serum and preovulatory follicular fluid. Serum and follicular fluid samples from thin (n = 12), moderate (n = 11), and obese (n = 16) cows underwent a H2O2 bioluminescence assay. Levels of H2O2 in each biofluid were then assessed to determine relationships with cow body condition and serum or follicular fluid metabolites. Levels of H2O2 did not differ among body condition categories. In thin cows, the serum H2O2 level was positively related to the abundance of 3 metabolites with antioxidant activity. Among all animals, the follicular fluid H2O2 level was positively associated with the abundance of 13 metabolites, many of which had antioxidant roles. The results suggest an impact of postpartum beef cow metabolism on ROS levels in preovulatory follicular fluid or serum and highlight the need for additional studies to further investigate this potential impactor of reproductive efficiency and sustainable beef production. [ABSTRACT FROM AUTHOR]

Habitat loss, fragmentation, and degradation of habitats are among the most pervasive impacts on species persistence. Mammals may vary in their response to these impacts, both in abundance and in physiological parameters. Herein, we verified how habitat quality influenced the small mammal nutritional status and stress levels among five semi‐deciduous forest remnants in the Brazilian Cerrado. To assess species' physiological responses, we used body condition as an indicator of nutritional status and neutrophil/lymphocyte (N/L) ratio as an indicator of chronic stress in Gracilinanus agilis and Rhipidomys macrurus. We sampled 264 animals belonging to the following species: G. agilis, Didelphis albiventris, Akodon montensis, Oligoryzomys spp., Rattus rattus, R. macrurus, Oecomys cleberi, Hylaeamys megacephalus, and three unidentified rodent species. We found no negative effect of reduced habitat quality on the body condition of G. agilis and R. macrurus, however, the N/L ratios of these species were lower only in high‐quality habitats, demonstrating that this parameter is an accurate indicator of chronic stress. Based on preliminary analysis, we also reported an impoverished fauna, mainly dominated by generalist species, in low‐quality habitats. Thus, we conclude that short‐term reduction in habitat quality leads to increased stress levels, which can in turn lead to future population declines and culminate in biotic homogenization. [ABSTRACT FROM AUTHOR]

Parasites negatively affect the fitness of ungulate hosts directly, and in wild ungulates, these effects may be synzootic with other stressors, such as limited nutritional resources. In the Arctic, muskoxen (Ovibos moschatus) occur in a highly seasonal environment and must rely on finite energetic resources for survival and productivity. We investigated the costs of gastrointestinal nematodes on the body condition and reproductive status of 141 muskoxen, on Banks Island, Canada, when the population was at a peak in numbers and density. Using a Partial Least Squares Path Modelling approach, we found that high adult nematode abundance was associated with lower body condition, and high parasite abundance was associated with female reproduction including the indirect effect through on body condition (n = 87). These findings suggest that individuals prioritize energetic reserves for reproduction over parasite defence. In fall 2003, a severe icing event that restricted access to forage was associated with high overwinter mortality of muskoxen and a population crash. Through direct and indirect costs of parasite infection on body condition and reproduction, the high abundance of parasites may have contributed to the effects of this extreme weather event. Understanding the mechanisms in which parasites impact fitness can help explain the ecological drivers of ungulate populations and predict the interactions between the environment and populations. [ABSTRACT FROM AUTHOR]

Urban areas, i.e. dense housing and reduced green spaces, can significantly impact avian health, through altering land use and increasing biotic and abiotic stress. This study assessed the association of urbanization on haemosporidian infections, vectors, immune response, and body condition in Parus major nestlings, across four classes of urbanization along an urban-to-rural gradient in Vienna, Austria. Contrary to our expectations, vector abundance remained consistent across the gradient, while an increase in leukocyte count is positively associated with total parasite intensity. We found that nestlings in more urbanized areas exhibited higher parasite intensity and altered immune response, as evidenced by variations in the heterophil to lymphocyte ratio and leukocyte counts. Culicidae female vectors were associated with nestlings' total parasites, scaled mass index, and industrial units. Nestlings in highly developed areas had higher infection rates than those in forests, suggesting increased exposure to infections. However, there was no clear relationship between total female vectors and total parasites. The level of urbanization negatively affected nestling body condition, with a decrease in fat deposits from forested to highly urbanized areas. Our findings highlight the complex interplay between urbanization, vector-borne parasite transmission, and host immune response, emphasizing the need for comprehensive urban planning to improve wildlife health and guarantee ecosystem functioning. Understanding how urbanization affects bird immunity and parasite infections is critical for adapting urban landscapes for wildlife health and ecosystem integrity. [ABSTRACT FROM AUTHOR]

Reproduction is known to be energetically and physiologically costly. Consequently, individuals in good condition are assumed to invest substantial resources in reproduction, while those in poor condition are unable to do so. This is particularly relevant in insects, where reproduction is a nutrient-limited process for males and females and is largely related to their energy reserves. Lepidopteran phytophagous insects are an ideal model to evaluate how larval nutrition affects adult reproductive strategies, because larval host plant is considered a key determinant of the adult phenotype and the performance of both males and females. We studied a capital breeder moth species, the European grapevine moth (Lobesia botrana), to investigate how male energy reserves, body condition and reproductive traits might influence female reproductive output, using different host plants as a means of obtaining different male quality. We found that the host cultivar for the larvae strongly influenced the energy reserves of male adult moths, affecting their body condition and ultimately their reproductive potential through the content of spermatophores they transfer to females at mating. Moreover, males having different levels of energy reserves may alter the allocation of energy between their body condition and spermatophore size and composition, supporting the idea that organisms can buffer the effect of nutritional constraints by changing allocation to different fitness-related traits. Females also seem to be able to adjust latency to oviposition accordingly. These results have important implications for understanding the population dynamics of this moth species. [ABSTRACT FROM AUTHOR]

Avian preen gland helps birds cope with their environment, although its overall functioning remains unclear. We shed light on the complexity of the preen gland's functioning by studying how multiple factors associate with gland morphology (size and shape) and physiology (wax secreted) in barn owls Tyto alba. Individual factors (sex, breeding stage, body condition) were more important predictors of preen gland than environmental factors (temperature, humidity, brood size). Sex, depending on breeding stage in adults, influenced preen gland traits, pointing to the preen gland's regulation by sex hormones and a greater pressure on females to protect their eggs, offspring and themselves throughout reproduction. Adults and fledglings in better condition had larger glands, pointing to the existence of physiological costs. Temperature and humidity, in interaction with plumage coloration, also influenced but to a lesser extent preen gland traits, suggesting that melanin pigmentation and preen gland act as superseding mechanisms when protecting plumage against microorganisms. Finally, fledglings living in larger broods had larger glands, suggesting a role for the social environment in preen gland's functioning. Overall, our study supports the idea that preen gland functions in diverse biological contexts within the same species and is thus subject to multiple selective pressures. [ABSTRACT FROM AUTHOR]

Female fecundity is dependent on age and mated status. Young female insects accumulate considerable fat stores to fuel energetically expensive ovary development and egg production. Consequently, younger females are expected to have more stored fat than older females while the latter should have larger eggloads than the former. Mating is expected to increase fecundity because male ejaculates contain fecundity-enhancing substances that stimulate egg development, ovulation and oviposition. We experimentally tested the effect of female age (young versus old) and mated status (virgin versus mated) on fat and eggloads in female Gryllus firmus field crickets (Orthoptera: Gryllidae), in addition to testing the prediction that young or mated females have higher resting metabolic rates (RMR) than old or virgin females because the former should be significantly more engaged in the energetically expensive activity of egg production than the latter. As predicted, we found that young females had more fat and fewer eggs than old females and that fat loads negatively correlated with fecundity across all females. Young females also exhibited higher RMR, as expected if egg production is energetically costly. Contrary to expectation, however, mated status had little effect on fat load, egg production or RMR. That mating had little effect on total egg production (i.e. stored and oviposited eggs) challenges the hypothesis that male fecundity-enhancing substances in the ejaculate stimulate egg production. Our experiment also permitted us to examine the validity of two popular indices of body condition, the scaled mass index (SMI) and residual body mass (R i). Neither index accurately represented the true treatment effects of age and mated status on fat load; however, the SMI reflected true fat content in young, but not old, females. • We tested effects of age and mated status on fat and eggloads in female Gryllus firmus. • Young females had more fat and fewer eggs than old females. • Fat loads were negatively correlated with fecundity across all females. • Young females had a higher resting metabolic rate (RMR) than old females. • Mated status had little effect on fat load, egg production or RMR. [ABSTRACT FROM AUTHOR]

Physical condition and temperament significantly correlate with the health and productivity of cattle. Excessively fat or extremely thin cows, suffer from a number of metabolic and immune disorders, have reduced fertility, produce less milk of low quality, and are more often culled for poor production and breeding. Bulls with impaired body condition have reduced libido and produce poor quality semen. Cows and bulls with a violent temperament have poorer carcass quality, are more often and easily injured and are also dangerous to stockmen. This work presents the most common methods of assessing the condition of cattle, and methods of establishing animals temperament. The constant progress in the development of new methods for evaluation of condition and temperament is taken into account, emphasizing the importance including artificial intelligence (AI), into research. At the same time, advantages and disadvantages of the selected methods were highlighted. [ABSTRACT FROM AUTHOR]

Abstract Monitoring the nutritional health of cetaceans has become increasingly important in a changing environment, where multiple stressors impact animals. Particularly for those species that require consumption of energy‐dense prey, such as the common dolphin. Thus far, no uniform measure for monitoring body condition has been recommended across cetaceans, and species‐specific measures may need to be developed if employed as a population condition indicator under Descriptor 1 of the Marine Strategy Framework Directive. Here, nine morphometric body condition indices were applied to long‐term common dolphin stranding data sets originating from Ireland and the UK. We report a recent decline in the nutritional health of common dolphins in the Celtic Seas ecoregion comparing animals from 2017 to 2019 to animals from 1990 to 2006, with an increase in cases of animals dying due to starvation. Using ordinal regression trees, ventral blubber thickness (VBT) was identified as the most important index to predict nutritional status, defined at necropsy, followed by the scaled mass index (SMI). Using generalised linear models, both the VBT and SMI indices differentiated individuals that died from chronic and acute causes of death (i.e., bycatch), where animals in chronic conditions had significantly thinner VBT and lower SMI. Both significant temporal and seasonal patterns in VBT were identified, with poorer body conditions observed during the autumn and better body conditions observed during the spring, as well as an overall decline detected in VBT during the study period. While VBT was positively correlated with total body length, SMI showed the opposite trend. The VBT index is recommended for monitoring nutritional health within the species when total body length and season are considered. Further research is needed to understand the underlying causes for the observed decline, including shifts in prey availability and/or quality, to inform targeted conservation management strategies.

ABSTRACT Myctophids are one of the most diverse and abundant fish families in the mesopelagic zone, making them a key component in the marine pelagic community. In the North Atlantic, Benthosema glaciale (glacier lantern fish) is considered the most abundant myctophid north of 35° N, yet some regions within its extensive range lack information on its basic biological parameters. We investigated the growth and described the distribution of B. glaciale in Icelandic waters, including the southern continental shelf, Iceland Basin, and Irminger Sea. Length distribution, growth, relative body condition, age, and otolith‐fish size relationships were analyzed from samples collected opportunistically with pelagic trawls during the International Ecosystem Summer Survey in the Nordic Seas (IESSNS) in July 2020. In total, 1374 individuals were caught, and only a subset of 225 were measured fresh at sea and 89 were frozen and dissected on land. Total lengths of fresh fish ranged from 38 to 85 mm, while dissected individuals ranged from 40 to 74 mm and were 2 to 6 years old. Located over the Reykjanes Ridge in the Iceland Basin region, individuals had a significantly higher mean standard length and mean age, and a lower mean body condition. We reported length–weight relationships for both fresh and frozen samples, indicating evidence that preserving of the specimens through freezing affected relationships. The von Bertalanffy growth curve was calculated along with significant otolith‐fish size relationships where r2 values ranged between 0.87 and 0.92. Our research highlights the importance of cross‐regional studies and provides baseline biology for B. glaciale in Icelandic waters, specifically in the southern continental slope and Reykjanes Ridge.

Nutritional status plays a vital role in regulating ovary activity. This regulation is mediated by the hypothalamus–pituitary–gonad axis and by effects exerted directly on the ovary. Therefore, to achieve the best reproductive performance, it is essential to know how the nutritional status affects the secretion of GnRH, gonadotrophins, and sex steroid hormones. Adequate body reserves and energy balance are critical for optimal reproductive performance in sheep and goats. However, over- or under-conditioned animals experience issues like extended anestrus, irregular ovarian cycles, and reduced conception. Body condition scoring allows for the evaluation of the relationships between adiposity, nutritional status, and fertility. Acute feed deficits briefly stimulate processes, but chronic restrictions suppress pulsatile LH release, disrupting ovarian function. The process of follicle development is a very complex one which involves intricate interactions between the pituitary gonadotrophins and metabolic hormones as well as between the locally produced factors by the ovarian somatic and germ cells including the IGF system and the TGF-β superfamily members. Genotype and nutrition are factors that have an impact on follicular development, and seasonal factors are also involved. This review will give a brief overview on how the body condition can be evaluated and the effects of nutrition on the hypothalamus–pituitary–gonad axis and ovarian activity, which are responsible for reproductive regulation. This paper presents a clear and reasonable summary of the pathway that runs from the nutritional status of small ruminants to ovarian activity through the hypothalamic–pituitary–gonadal axis. This review summarizes methods for body condition evaluation in small ruminants and evidence regarding acute versus prolonged nutritional impacts on the hypothalamic–pituitary–gonadal axis and ovarian activity controlling reproduction.

Abstract Background External tags, such as transmitters and loggers, are often used to study bat movements. However, physiological and behavioural effects on bats carrying tags have rarely been investigated, and recommendations on the maximum acceptable tag mass are rather based on rules of thumb than on rigorous scientific assessment. Methods We conducted a comprehensive three-step assessment of the potential physiological and behavioural effects of tagging bats, using common noctules Nyctalus noctula as a model. First, we examined seasonal changes in body mass. Second, we predicted and then measured potential changes in flight metabolic rate in a wind tunnel. Third, we conducted a meta-analysis of published data to assess effects of different tag masses on the weight and behaviour of bats. Results Individual body mass of common noctules varied seasonally by 7.0 ± 2.6 g (range: 0.5–11.5 g). Aerodynamic theory predicted a 26% increase in flight metabolic rate for a common noctule equipped with a 3.8 g tag, equating to 14% of body mass. In a wind tunnel experiment, we could not confirm the predicted increase for tagged bats. Our meta-analysis revealed a weak correlation between tag mass and emergence time and flight duration in wild bats. Interestingly, relative tag mass (3–19% of bat body mass) was not related to body mass loss, but bats lost more body mass the longer tags were attached. Notably, relatively heavy bats lost more mass than conspecifics with a more average body mass index. Conclusion Because heavy tags (> 3 g) were generally used for shorter periods of time than lighter tags (~ 1 g), the long-term effects of heavy tags on bats cannot be assessed at this time. Furthermore, the effects of disturbance and resource distribution in the landscape cannot be separated from those of tagging. We recommend that tags weighing 5–10% of a bat’s mass should only be applied for a few days. For longer studies, tags weighing less than 5% of a bat's body mass should be used. To avoid adverse effects on bats, researchers should target individuals with average, rather than peak, body mass indices.

The effects of recent climate change on the phenology of avian breeding and migration, geographical range shifts, and decreasing migration distances are well documented. Only a few studies have focused on the long-term influence of these changes on the body condition of migrants, which is important as it is likely to affect the fitness of the whole population. Eurasian blackcaps have adapted their migratory behaviour to changing ecological factors. These changes seem to favour the species and its migratory populations have increased over the last decades in Europe. In the present study, we analysed the body condition index of juvenile blackcaps at their stop-over site in the southern Baltic region during autumn migration from 1967 to 2006. This index was distinctly higher since the 1990s than in the middle of the 1960s, when the number of migrating blackcaps was at least twofold lower. Moreover, there was a reduction in recapture rates of blackcaps from 14% to 6% during these periods which may imply that warblers were staying for a shorter time at the stop-over site as their body condition was higher. We hypothesized that higher berry crop availability resulted in the higher condition of migrating blackcaps. Body condition index also reflecting fuel load in migrants was higher in long-distance blackcaps compared to the short-distance ones. As the former are time-minimizing migrants, their higher body condition/fuel load may allow them to migrate faster to wintering grounds in sub-Saharan Africa. [ABSTRACT FROM AUTHOR]

Determining the factors influencing reproductive rates is important for modeling and managing wildlife populations. In ungulates, these vital rates are often related to intrinsic characteristics such as age and body condition. We studied mid-winter pregnancy and early reproductive outcomes (offspring viability) in a reintroduced elk (Cervus canadensis) population in southeastern Kentucky, USA, modeling these rates as a function of age, body condition score, and body mass with generalized linear mixed-effects models (GLMMs) fit within an information-theoretic framework to determine which factors best predicted reproductive potential. Our models for pregnancy status suggested that pregnancy was strongly correlated with body mass and weakly with age and body condition, while models for offspring viability suggested that none of the covariates measured were predictive of parturition and offspring viability. While body mass appeared to be the strongest correlate of reproductive potential in this population, other physiological and nutritional variables likely play a role in pregnancy or fetal survival, and future work should aim to understand how these parameters both influence reproduction and are influenced by habitat management. [ABSTRACT FROM AUTHOR]

Nutritional status plays a vital role in regulating ovary activity. This regulation is mediated by the hypothalamus–pituitary–gonad axis and by effects exerted directly on the ovary. Therefore, to achieve the best reproductive performance, it is essential to know how the nutritional status affects the secretion of GnRH, gonadotrophins, and sex steroid hormones. Adequate body reserves and energy balance are critical for optimal reproductive performance in sheep and goats. However, over- or under-conditioned animals experience issues like extended anestrus, irregular ovarian cycles, and reduced conception. Body condition scoring allows for the evaluation of the relationships between adiposity, nutritional status, and fertility. Acute feed deficits briefly stimulate processes, but chronic restrictions suppress pulsatile LH release, disrupting ovarian function. The process of follicle development is a very complex one which involves intricate interactions between the pituitary gonadotrophins and metabolic hormones as well as between the locally produced factors by the ovarian somatic and germ cells including the IGF system and the TGF-β superfamily members. Genotype and nutrition are factors that have an impact on follicular development, and seasonal factors are also involved. This review will give a brief overview on how the body condition can be evaluated and the effects of nutrition on the hypothalamus–pituitary–gonad axis and ovarian activity, which are responsible for reproductive regulation. This paper presents a clear and reasonable summary of the pathway that runs from the nutritional status of small ruminants to ovarian activity through the hypothalamic–pituitary–gonadal axis. This review summarizes methods for body condition evaluation in small ruminants and evidence regarding acute versus prolonged nutritional impacts on the hypothalamic–pituitary–gonadal axis and ovarian activity controlling reproduction. [ABSTRACT FROM AUTHOR]

Urban areas—characterized by high human densities, buildings, and impermeable surfaces—are increasing globally and represent a leading threat to wildlife by drastically altering the natural resources wildlife species are accustomed to. Prior work suggests that living in urban habitats can cause wildlife to show increased cholesterol levels. In biomedical research, elevated cholesterol is linked to disease, but the consequence of elevated cholesterol in wildlife remains unclear. We measured total cholesterol in European Starlings (Sturnus vulgaris), an urban-adapted species, across an urban and a rural site. We asked: (1) Do urban starlings have elevated cholesterol? and (2) Is elevated cholesterol correlated to negative physiological outcomes in starlings? We found that nestlings from the urban (N = 16) and rural (N = 98) sites showed similar cholesterol, but adult starlings from the urban (N = 5) habitat showed elevated cholesterol compared to rural (N = 36) birds. However, elevated cholesterol was not correlated with increased oxidative damage to DNA, lowered body condition, or increased baseline glucocorticoids across any age class, suggesting that elevated cholesterol did not come at a physiological cost to starlings. Future work is needed to explore what mechanism(s) drive variation in cholesterol across urban and rural birds, as well as whether any long-term consequences of elevated cholesterol exist. Les zones urbaines, caractérisées par de densités humaines élevées et des bâtiments et des surfaces imperméables, augmentent au niveau mondial et représentent une menace majeure pour la faune sauvage en modifiant radicalement les ressources naturelles auxquelles les espèces sont habituées. Des travaux antérieurs suggèrent que vivre dans des habitats urbains peut entraîner une augmentation des taux de cholestérol chez la faune sauvage. Dans la recherche biomédicale, un taux de cholestérol élevé est lié à la maladie, mais les conséquences d'un taux de cholestérol élevé chez la faune sauvage ne sont pas claires. Nous mesurâmes le cholestérol total chez l'étourneau sansonnet (Sturnus vulgaris), une espèce adaptée à la ville, sur un site urbain et un site rural. Nous demandâmes: (1) est-ce que les étourneaux sansonnets urbains ont un taux de cholestérol élevé? et (2) est-ce qu'un taux de cholestérol élevé est corrélé à des résultats physiologiques négatifs chez les étourneaux? Nous constatâmes que les oisillons des sites urbains (N = 16) et ruraux (N = 98) présentaient un taux de cholestérol similaire, mais que les étourneaux adultes de l'habitat urbain (N = 5) présentaient un taux de cholestérol élevé par rapport aux étourneaux adultes de l'habitat rural (N = 36). Cependant, un taux de cholestérol élevé n'était pas corrélé à une augmentation des dommages oxydatifs de l'ADN, à une condition corporelle réduite ou à une augmentation des glucocorticoïdes de base dans toutes les classes d'âge, ce qui suggère qu'un taux de cholestérol élevé n'a pas eu de coût physiologique pour les étourneaux. Des travaux futurs sont nécessaires pour explorer le(s) mécanisme(s) qui déterminent la variation du cholestérol chez les oiseaux urbains et ruraux, ainsi que pour déterminer s'il existe des conséquences à long terme d'un taux de cholestérol élevé. Mots-clés: condition corporelle, dommage à l'ADN, glucocorticoïdes, urbanisation. [ABSTRACT FROM AUTHOR]

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Background: External tags, such as transmitters and loggers, are often used to study bat movements. However, physiological and behavioural effects on bats carrying tags have rarely been investigated, and recommendations on the maximum acceptable tag mass are rather based on rules of thumb than on rigorous scientific assessment. Methods: We conducted a comprehensive three-step assessment of the potential physiological and behavioural effects of tagging bats, using common noctules Nyctalus noctula as a model. First, we examined seasonal changes in body mass. Second, we predicted and then measured potential changes in flight metabolic rate in a wind tunnel. Third, we conducted a meta-analysis of published data to assess effects of different tag masses on the weight and behaviour of bats. Results: Individual body mass of common noctules varied seasonally by 7.0 ± 2.6 g (range: 0.5–11.5 g). Aerodynamic theory predicted a 26% increase in flight metabolic rate for a common noctule equipped with a 3.8 g tag, equating to 14% of body mass. In a wind tunnel experiment, we could not confirm the predicted increase for tagged bats. Our meta-analysis revealed a weak correlation between tag mass and emergence time and flight duration in wild bats. Interestingly, relative tag mass (3–19% of bat body mass) was not related to body mass loss, but bats lost more body mass the longer tags were attached. Notably, relatively heavy bats lost more mass than conspecifics with a more average body mass index. Conclusion: Because heavy tags (> 3 g) were generally used for shorter periods of time than lighter tags (~ 1 g), the long-term effects of heavy tags on bats cannot be assessed at this time. Furthermore, the effects of disturbance and resource distribution in the landscape cannot be separated from those of tagging. We recommend that tags weighing 5–10% of a bat's mass should only be applied for a few days. For longer studies, tags weighing less than 5% of a bat's body mass should be used. To avoid adverse effects on bats, researchers should target individuals with average, rather than peak, body mass indices. [ABSTRACT FROM AUTHOR]

Warming temperatures in the Gulf of Alaska have been linked to recruitment failure in Pacific cod (Gadus macrocephalus), but the mechanisms and timing of mortality events for juveniles are unclear. To date, limited research has focused on overwintering success, and the knowledge of juvenile ecology and physiology is based entirely on summer observations. Here, we investigate the changes in body condition, diet composition, and tissue-specific fatty acid (FA) storage for age-0 Pacific cod in Kodiak, Alaska, from February to December during 2018 and 2020. We observed protracted nearshore residency from June to December. Cod body condition (K dry) and predicted weight at length were lowest in October, November, and December. Although not different interannually, diet composition varied seasonally, which corresponded to an increase in cod length. A range of condition metrics (HSIwet, FA concentration in liver tissue, and the % of whole body FAs stored in the liver) began to increase in September. Cod prioritized growth during the summer, while in the autumn and pre-winter they allocated more energy into lipid storage. We conclude that seasonal changes in tissue-specific FA storage and pre-winter fish conditions are important factors to consider for understanding overwintering potential of juvenile Pacific cod. [ABSTRACT FROM AUTHOR]

Migratory, long‐lived animals are an important focus for life‐history theory because they manifest extreme trade‐offs in life‐history traits: delayed maturity, low fecundity, variable recruitment rates, long generation times, and vital rates that respond to variation across environments. Galapagos tortoises are an iconic example: they are long‐lived, migrate seasonally, face multiple anthropogenic threats, and have cryptic early life‐history stages for which vital rates are unknown. From 2012 to 2021, we studied the reproductive ecology of two species of Galapagos tortoises (Chelonoidis porteri and C. donfaustoi) along elevation gradients that coincided with substantial changes in climate and vegetation productivity. Specifically, we (1) measured the body and reproductive condition of 166 adult females, (2) tracked the movements of 33 adult females using global positioning system telemetry, and monitored their body condition seasonally, (3) recorded nest temperatures, clutch characteristics, and egg survival from 107 nests, and (4) used radiotelemetry to monitor growth, survival, and movements of 104 hatchlings. We also monitored temperature and rainfall from field sites, and remotely sensed primary productivity along the elevation gradient. Our study showed that environmental variability, mediated by elevation, influenced vital rates of giant tortoises, specifically egg production by adult females and juvenile recruitment. Adult females were either elevational migrants or year‐round lowland residents. Migrants had higher body condition than residents, and body condition was positively correlated with the probability of being gravid. Nests occurred in the hottest, driest parts of the tortoise's range, between 6 and 165 m elevation. Clutch size increased with elevation, whereas egg survival decreased. Hatchling survival and growth were highest at intermediate elevations. Hatchlings dispersed rapidly to 100–750 m from their nests before becoming sedentary (ranging over <0.2 ha). Predicted future climates may impact the relationships between elevation and vital rates of Galapagos tortoises and other species living across elevation gradients. Resilience will be maximized by ensuring the connectivity of foraging and reproductive areas within the current and possible future elevational ranges of these species. [ABSTRACT FROM AUTHOR]