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To maximize their fitness, individuals of one sex can display discrete reproductive phenotypes, called alternative reproductive tactics ( ARTs). Individuals following ARTs show behavioural variation, which might result in differences in energy intake and expenditure. However, few studies have compared activity budgets and non-sexual behaviour of individuals following ARTs in nature. We studied male African striped mice Rhabdomys pumilio, which can follow three ARTs: (1) breeding male of a group of females; (2) philopatrics remaining in their natal group; or (3) solitary living roamers. We predicted that each tactic is characterized by its specific activity budget, representing alternative energy trade-offs. We conducted focal animal observations on 70 males following ARTs. Roamers had higher travelling rates than philopatrics, and breeders had larger daily range sizes compared to philopatrics but not roamers. Philopatrics had higher foraging rates than breeders and showed more socio-positive behaviour than roamers. Breeders and philopatrics were in their nest more often than roamers, potentially engaging in social interactions with other group members. Roamers were chased off more often than breeders, but the three tactics did not differ concerning rates of socio-negative behaviour. Overall, philopatrics allocated their time towards behaviours that would increase body mass and survival probability, which could improve the probability to switch to a tactic of higher reproductive success. In contrast, breeders and roamers allocated their time towards behaviours that would increase their chances to mate. In conclusion, following ARTs results in contrasting activity budgets that reflect the differences in reproductive behaviours observed between tactics. [ABSTRACT FROM AUTHOR]

Urbanization is a persistent and widespread driver of global environmental change, potentially shaping evolutionary processes due to genetic drift and reduced gene flow in cities induced by habitat fragmentation and small population sizes. We tested this prediction for the eastern grey squirrel (Sciurus carolinensis), a common and conspicuous forest-dwelling rodent, by obtaining 44K SNPs using reduced representation sequencing (ddRAD) for 403 individuals sampled across the species' native range in eastern North America. We observed moderate levels of genetic diversity, low levels of inbreeding, and only a modest signal of isolation-by-distance. Clustering and migration analyses show that estimated levels of migration and genetic connectivity were higher than expected across cities and forested areas, specifically within the eastern portion of the species' range dominated by urbanization, and genetic connectivity was less than expected within the western range where the landscape is fragmented by agriculture. Landscape genetic methods revealed greater gene flow among individual squirrels in forested regions, which likely provide abundant food and shelter for squirrels. Although gene flow appears to be higher in areas with more tree cover, only slight discontinuities in gene flow suggest eastern grey squirrels have maintained connected populations across urban areas in all but the most heavily fragmented agricultural landscapes. Our results suggest urbanization shapes biological evolution in wildlife species depending strongly on the composition and habitability of the landscape matrix surrounding urban areas., (© 2023 John Wiley & Sons Ltd.)

Background: Pastoralists live in challenging environments, which may be accompanied by unique activity, energy, and water requirements., Aim: Few studies have examined whether the demands of pastoralism contribute to differences in total energy expenditure (TEE) and water turnover (WT) compared to other lifestyles., Subjects and Methods: Accelerometer-derived physical activity, doubly labelled water-derived TEE and WT, and anthropometric data were collected for 34 semi-nomadic Daasanach adults from three northern Kenyan communities with different levels of pastoralist activity. Daasanach TEEs and WTs were compared to those of other small-scale and industrialised populations., Results: When modelled as a function of fat-free-mass, fat-mass, age, and sex, TEE did not differ between Daasanach communities. Daasanach TEE (1564-4172 kcal/day) was not significantly correlated with activity and 91% of TEEs were within the range expected for individuals from comparison populations. Mean WT did not differ between Daasanach communities; Daasanach absolute (7.54 litres/day men; 7.46 litres/day women), mass-adjusted, and TEE-adjusted WT was higher than most populations worldwide., Conclusions: The similar mass-adjusted TEE of Daasanach and industrialised populations supports the hypothesis that habitual TEE is constrained, with physically demanding lifestyles necessitating trade-offs in energy allocation. Elevated WT in the absence of elevated TEE likely reflects a demanding active lifestyle in a hot, arid climate.

Insufficient physical activity is a major risk factor for cardiometabolic disease (i.e., unhealthy weight gain, heart disease, and diabetes) in humans and may also negatively affect health of primates in human care. Effects of physical activity on energy expenditure and cardiometabolic health are virtually unstudied in nonhuman primates. We investigated physical activity and metabolic markers in 15 adult ring-tailed lemurs (Lemur catta) and 11 Coquerel's sifakas (Propithecus coquereli) at the Duke Lemur Center during a period of low activity in winter when the animals were housed in buildings (with outdoor access) and a period of high activity when individuals were free-ranging in large, outdoor, forested enclosures. We compared body mass, blood glucose, triglycerides, HDL- and LDL-cholesterol, physical activity via accelerometry, and total energy expenditure (TEE) via the doubly labeled water method (in ring-tailed lemurs only) between both conditions. Both species were more active and had a lower body mass in summer. Ring-tailed lemurs had a higher TEE and lower triglyceride levels in summer, whereas sifaka had higher triglyceride levels in summer. Individuals that increased their activity more, also lost more body mass. Individuals that lost more body mass, also had a positive change in HDL-cholesterol (i.e., higher values in summer). Changes in activity were not associated with changes in markers of metabolic health, body fat percentage and TEE (both unadjusted and adjusted for body composition). Older age was associated with lower activity in both species, and decreased glucose in ring-tailed lemurs, but was otherwise unrelated to metabolic markers and, for ring-tailed lemurs, adjusted TEE. Overall, body mass was lower during summer but the increase in physical activity did not strongly influence metabolic health or TEE in these populations., (© 2023 The Authors. American Journal of Primatology published by Wiley Periodicals LLC.)

Continuous multiday ultramarathon competitions are increasingly popular and impose extreme energetic and nutritional demands on competitors. However, few data have been published on energy expenditure during these events. Here, we report doubly labeled water-derived measures of total energy expenditure (in kilocalories per day) and estimated physical activity level (PAL: total energy expenditure/basal metabolic rate) collected from five elite and subelite finishers (four males and one female, age 34.6 ± 4.9 years)-and nutritional intake data from the winner-of the Cocodona 250, a ∼402-km race in Arizona, and from a fastest-known-time record (one male, age 30 years) on the ∼1,315-km Arizona Trail. PAL during these events exceeded four times basal metabolic rate (Cocodona range: 4.34-6.94; Arizona Trail: 5.63). Combining the results with other doubly labeled water-derived total energy expenditure data from ultraendurance events show a strong inverse relationship between event duration and PAL (r2 = .68, p < .0001). Cocodona race duration was inversely, though not significantly, associated with PAL (r2 = .70, p = .08). Water turnover varied widely between athletes and was not explained by PAL or body mass. The Cocodona race winner met ∼53% of energy demand via dietary intake, 85.6% of which was carbohydrate, while ∼47% of energy demand was met via catabolism of body energy stores. Together, these results illustrate the energetic deficits incurred during competitive continuous multiday ultramarathon efforts and implicate macronutrient absorption and/or storage as key factors in ultramarathon performance.

We must differentiate between stressful and harsh environments to understand animals' resilience to global change. Harshness is not stress. Stressful environments activate the physiological stress response to increase energy availability, while harsh environments inhibit the physiological stress response to save energy., Competing Interests: Declaration of interests No interests are declared., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Urban habitats provide wildlife with predictable, easily accessible and abundant food sources in the form of human food waste. Urban eastern gray squirrels ( Sciurus carolinensis ) are commonly observed feeding in trash bins, but we lack data regarding the type, quantity and seasonal changes in food waste usage. We observed five trash bins on an urban university campus during four different observation periods. We recorded the time squirrels spent on and inside trash bins and type of retrieved food items. We also recorded ambient temperature, human presence and trash bin filling. Moreover, we determined changes in squirrel population density in a natural and three anthropogenic habitats during the same periods. Trash bins were fuller when human presence was higher. The higher human presence, the more squirrels went on and inside the bin, but there was no effect on number of retrieved food items. Trash bin usage by squirrels decreased when ambient temperature and bin filling increased. Most food items were retrieved during the coldest observation period, a period of high human presence, and the majority of retrieved food items were starchy foods (e.g., bread, French fries). The relationship between the number of squirrels observed along transects and a measure of urbanization, the normalized difference built-up index, was negative in periods with high ambient temperatures and positive in periods with low ambient temperatures, indicating winter may be less challenging in urban areas, likely facilitated by the availability of anthropogenic food sources, allowing a higher level of activity throughout winter., Supplementary Information: The online version contains supplementary material available at 10.1007/s42991-022-00326-3., Competing Interests: Conflict of interestThe authors declare that they have no conflict of interest., (© The Author(s) under exclusive licence to Deutsche Gesellschaft für Säugetierkunde 2022, corrected publication 2022Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.)

Matschie's tree kangaroo (Dendrolagus matschiei) is an endangered arboreal marsupial native to Papua New Guinea. Detailed field studies of its behavior and ecology are scarce due largely to its occupation of remote cloud forests and cryptic nature. Although this species has been in human care since the 1950s, much of its biology is still unknown. The current ex situ population is not sustainable due to health and reproductive problems, believed to stem largely from issues with diet and obesity. To better assess potential discrepancies between energy requirements and energy intake, we sought to 1) quantify total energy expenditure (TEE) of two zoo-housed Matschie's tree kangaroos (body mass = 9.0-9.7 kg) on a diet composed largely of leafy browse; 2) quantify food and macronutrient intake, apparent dry matter macronutrient digestibility, and metabolizable energy (ME) intake over a 14-month period; and 3) test for seasonal changes in ME intake due to seasonal differences in the varieties of leafy browse offered. Using the doubly labeled water method, we determined TEE for the female (288 kcal day -1) and male (411 kcal day -1). Resulting mean TEE was well below the expected value for marsupials and macropods (i.e., ~60% of the expected value based on body mass). The mean calculated ME intakes for the female and male were 307 kcal day-1 and 454 kcal day-1, respectively. There were significant seasonal differences in ME intakes, driven by reduced intake in the autumn. These results demonstrate that Matschie's tree kangaroos can be maintained at healthy body weights and conditions on fiber-rich and browse-heavy diets. Our findings contribute important insights into tree kangaroo energetics and physiology and can be applied to help reformulate the diet of Matschie's tree kangaroos at captive facilities to improve population health and sustainability., Competing Interests: The authors have declared that no competing interests exist.

Objective: High levels of total energy expenditure (TEE, kcal/day) have been documented among numerous human populations such as tropical climate horticulturalists and high-altitude agriculturalists. However, less work has been conducted among highly physically active cold climate populations., Methods: In October 2018, TEE was measured using the doubly labeled water (TEE DLW , N = 10) and flex-heart rate methods (TEE HR , N = 24) for 6-14 days among reindeer herders (20-62 years) in northern Finland during an especially physically demanding, but not seasonally representative, period of the year for herders-the annual reindeer herd roundup. Self-reported dietary intake was also collected during TEE measurement periods. TEE was then compared to that of hunter gatherer, farming, and market economies., Results: During the herd roundup, herders expended a mean of 4183 ± 949 kcal/day as measured by the DLW method, which was not significantly different from TEE HR . Mean caloric intake was 1718 ± 709 kcal/day, and was significantly lower than TEE DLW and TEE HR (p < .001). Herder TEE DLW was significantly higher than that of hunter gatherer (p = .0014) and market (p < .0014) economy populations; however, herder TEE DLW was not different from that of farming populations (p = .91)., Conclusion: High TEE and low caloric intake among herders reflect the extreme demands placed on herders during the annual herd round up. Although TEE DLW was similar between cold climate herders and hot climate farming populations, there are likely differences in how that TEE is comprised, reflecting the local ecologies of these populations., (© 2021 Wiley Periodicals LLC.)

Low total energy expenditure (TEE, MJ/d) has been a hypothesized risk factor for weight gain, but repeatability of TEE, a critical variable in longitudinal studies of energy balance, is understudied. We examine repeated doubly labeled water (DLW) measurements of TEE in 348 adults and 47 children from the IAEA DLW Database (mean ± SD time interval: 1.9 ± 2.9 y) to assess repeatability of TEE, and to examine if TEE adjusted for age, sex, fat-free mass, and fat mass is associated with changes in weight or body composition. Here, we report that repeatability of TEE is high for adults, but not children. Bivariate Bayesian mixed models show no among or within-individual correlation between body composition (fat mass or percentage) and unadjusted TEE in adults. For adults aged 20-60 y (N = 267; time interval: 7.4 ± 12.2 weeks), increases in adjusted TEE are associated with weight gain but not with changes in body composition; results are similar for subjects with intervals >4 weeks (N = 53; 29.1 ± 12.8 weeks). This suggests low TEE is not a risk factor for, and high TEE is not protective against, weight or body fat gain over the time intervals tested., (© 2022. The Author(s).)

Marine mammals are thought to have an energetically expensive lifestyle because endothermy is costly in marine environments. However, measurements of total energy expenditure (TEE; kcal day-1) are available only for a limited number of marine mammals, because large body size and inaccessible habitats make TEE measurements expensive and difficult to obtain for many taxa. We measured TEE in 10 adult common bottlenose dolphins (Tursiops truncatus) living in natural seawater lagoons at two facilities (Dolphin Research Center and Dolphin Quest) using the doubly labeled water method. We assessed the relative effects of body mass, age and physical activity on TEE. We also examined whether TEE of bottlenose dolphins, and more generally of marine mammals, differs from that expected for their body mass compared with other eutherian mammals, using phylogenetic least squares (PGLS) regressions. There were no differences in body mass or TEE (unadjusted TEE and TEE adjusted for fat-free mass) between dolphins from the two facilities. Our results show that adjusted TEE decreased and fat mass increased with age. Different measures of activity were not related to age, body fat or adjusted TEE. Both PGLS and the non-phylogenetic linear regression indicate that marine mammals have an elevated TEE compared with that of terrestrial mammals. However, bottlenose dolphins expended 17.1% less energy than other marine mammals of similar body mass. The two oldest dolphins (>40 years) showed a lower TEE, similar to the decline in TEE seen in older humans. To our knowledge, this is the first study to show an age-related metabolic decline in a large non-human mammal., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2021. Published by The Company of Biologists Ltd.)

African elephants, the largest land animal, face particular physiological challenges in captivity and the wild. Captive elephants can become over- or under-conditioned with inadequate exercise and diet management. Few studies have quantified body composition or water turnover in elephants, and none to date have examined longitudinal responses to changes in diet or air temperature. Using the stable isotope deuterium oxide ( 2 H 2 O), we investigated changes in body mass, estimated fat-free mass (FFM, including fat-free gut content) and body fat in response to a multi-year intervention that reduced dietary energy density for adult African elephants housed at the North Carolina Zoo. We also examined the relationship between air temperature and water turnover. Deuterium dilution and depletion rates were assayed via blood samples and used to calculate body composition and water turnover in two male and three female African elephants at six intervals over a 3-year period. Within the first year after the dietary intervention, there was an increase in overall body mass, a reduction in body fat percentage and an increase in FFM. However, final values of both body fat percentage and FFM were similar to initial values. Water turnover (males: 359 ± 9 l d -1 ; females: 241 ± 28 l d -1 ) was consistent with the allometric scaling of water use in other terrestrial mammals. Water turnover increased with outdoor air temperature. Our study highlights the physiological water dependence of elephants and shows that individuals have to drink every 2-3 days to avoid critical water loss of approximately 10% body mass in hot conditions., Competing Interests: We report no competing interests., (© 2020 The Authors.)

Individuals that are capable of accumulating appropriate fat stores are assumed to have selective advantages when food becomes scarce. Similarly to species from temperate zones, some species inhabiting arid areas accumulate fat stores prior to periods of food limitation. Yet, we have little knowledge concerning seasonal variation in body composition and the relationship between fat store size and disappearance risk in species from arid habitats. Using the water dilution method, we examined the body composition of African striped mice ( Rhabdomys pumilio ) living in a seasonal habitat with a long food-restricted dry season. We tested for seasonal changes in body composition ( N =159 measurements of 113 individuals) and whether dry season survival was related to fat mass ( N =66 individuals). Fat stores were similar in size at the onset and the end of the dry season, but surprisingly smaller at the onset of the moist breeding season. Fat stores showed a negative relationship with food availability. Individual variation in fat stores was not associated with disappearance risk, but there was a positive association of disappearance risk with body mass. Increased disappearance risk of heavy individuals suggests elevated dispersal rates in competitive individuals. This study suggests that non-breeding philopatric striped mice do not accumulate large fat stores prior to the food-limited dry season but that they might mobilize fat stores at the onset of the breeding season to satisfy the energetic demands of reproduction and/or to decrease costs associated with larger fat stores, such as increased predation risk., Competing Interests: Competing interestsThe authors declare no competing or financial interests., (© 2019. Published by The Company of Biologists Ltd.)

In many species, males follow alternative reproductive tactics (ARTs), where one tactic (called bourgeois) has much higher reproductive success than alternative tactics followed by males with lower competitive ability. The extent to which ARTs differ in energetic costs is unknown, but it is important to understand the fitness payoffs of ARTs. We studied male African striped mice (Rhabdomys pumilio) which follow one of three ARTs: heavy bourgeois males defend harems of females and have 10 times higher reproductive success than smaller roamers, which have ten times higher reproductive success than philopatric males, which remain in their natal group and are the smallest males. Bourgeois and philopatric males live in social groups that defend one territory, while roamers are solitary and roam over larger areas. We predicted that roamers will face higher energetic costs compared to group-living males because they do not gain thermoregulatory benefits of huddling in groups and might travel larger distances as they have larger home ranges. We measured daily energy expenditure (DEE) of 30 males, resting metabolic rate (RMR) of 79 males, travel distances and daily ranges of 31 males and changes in body mass of 51 males. Roamers had higher DEE and higher RMR than both types of group-living males. Philopatric males had shorter travel distances and smaller daily ranges than both roamers and bourgeois males, which did not differ from each other. This indicates that the higher DEE of roamers compared to bourgeois males cannot be explained by larger travel distances. Philopatrics gained body mass faster than bourgeois males and roamers, thereby increasing their competitive ability and thus the probability of later switching to a tactic of higher reproductive success. Our results suggest that roamers suffer energetic costs that might reduce their ability of gaining body mass and thus the likelihood of switching to the bourgeois tactic, indicating evolutionary trade-offs between investing energy into roaming versus gaining body mass., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Animals that spend more energy than they obtain risk entering allostatic overload, reducing survival and fitness. They are predicted to adjust their daily energy expenditure (DEE) during periods of food scarcity. Adjustments of DEE to changes in food availability have been well-studied in species in temperate zones during winter, but less so in species enduring seasonal droughts. Likely mechanisms regulating DEE involve adjustments of activity and maintenance metabolism. Species that experience seasonal droughts and changes in food availability, like the African striped mouse (Rhabdomys pumilio), are appropriate model organisms to study the regulation of seasonal changes of DEE. We quantified DEE using the 'doubly labelled water' method, measured resting metabolic rate (RMR), and concomitantly determined activity levels using all-day focal observations of 69 free-living striped mice in the cold moist season with high food availability and the hot dry season with low food availability. Striped mice decreased their DEE in the food scarce dry season using multiple mechanisms, especially reductions in RMR, and reduced overall physical activity. This was further facilitated passively by reduced thermoregulatory costs. Our study demonstrates that animals reduce DEE via active and passive mechanisms in food-restricted environments, and highlights that several environmental factors should be considered simultaneously when aiming to understand how animals cope with harsh environments.

Family groups with helpers occur in several species of fish, birds and mammals. In such cooperatively breeding species all group members help with raising the offspring, i.e. parents and offspring from previous litters. While the ecological reasons and ultimate consequences of allo-parental care have been studied in detail, we know little about its physiological regulation. We propose three alternative hypotheses for the endocrine regulation of allo-parental care. 1. The neoteny-helper hypothesis predicts that helpers that did not undergo adolescence yet show helping behavior without any endocrine mechanisms activating it, as helping is the default response towards infant stimuli. The endocrine changes during adolescence would then deactivate helping behavior. 2. The parent-helper hypothesis predicts that helpers undergo the same endocrine changes as parents (increased prolactin and corticosterone levels; decreased testosterone in males but increased estrogen in females). We predict that this hypothesis is especially important in post-adolescent helpers. 3. The helper-specific hypothesis predicts that there are specific endocrine mechanisms that only exist in helpers but not in breeders. We review evidence for these three hypotheses in 23 species of fish, birds, and mammals. We found no evidence for the helper-specific hypothesis but for both other hypotheses. As predicted, this depended on whether helpers were pre- or post-adolescent, but information on whether or not helpers underwent adolescence was often missing. Thus, future studies should investigate whether or not helpers have reached sexual maturity, differentiate between pre- and post-adolescent helpers, and study behavioral changes in helping behavior during adolescence. We conclude that the neurobiological circuits in the brain necessary for allo-parental care might often be the default stage in helpers from cooperative breeding species, which might be deactivated by specific endocrine mechanisms during adolescence, and then would need reactivation for allo-parental and parental care., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Resting metabolic rate (RMR) influences energy allocation to survival, growth, and reproduction, and significant seasonal changes in RMR have been reported. According to one hypothesis, seasonal changes in RMR are mainly attributable to seasonal changes in ambient temperature (T a ) and food availability. Studies on species from the temperate zone indicated that food availability is the main driver. However, whether this is generally true is unknown, because studies from the tropics and subtropics, where most species live, are rare. We studied the African striped mouse (Rhabdomys pumilio) inhabiting a seasonal environment with hot dry seasons with low food availability and cold moist seasons with high food availability. Using 603 RMR measurements of 277 individuals, we investigated the relative importance of food availability and T a on RMR during selected periods, in which one extrinsic factor varied while the other factor was relatively constant. At similar T a , residual RMR increased with increasing levels of food availability. In contrast, different T a did not influence residual RMR at similar levels of food availability. Thus, our study on a subtropical species gives support to the hypothesis, derived from temperate zone species, that food availability mainly drives seasonal changes in RMR.

Diverse motivational triggers, including diet, elicit stereotypic behavior. We investigated whether diets comprised of different protein levels but similar levels of energy were associated with the occurrence of locomotor stereotypies in the striped mouse Rhabdomys dilectus chakae. In a first experiment, 20 stereotypic and 20 non-stereotypic (10 subjects per sex and per group) juvenile (40 days old) subjects were placed on baseline (BP), high (HP) or low protein (LP) diet treatments (120 subjects in total). All subjects initially identified as stereotypic displayed stereotypic behavior in the BP and HP treatments on Days 60-63 and Days 80-83 compared to 35% and 12.5% of LP subjects, respectively. Moreover, LP subjects displayed lower levels of activity and stereotypic behavior than BP and HP subjects. Those identified as non-stereotypic never displayed stereotypy. In a second experiment, 48 individuals, bred and reared on LP and whose parents were stereotypic, were assigned to either HP (13 males, 12 females) or LP (12 males, 11 females) treatments at 50 days of age for 30 days. Stereotypy was three times less likely to occur in the LP than the HP treatment, and activity was greater in LP-HP individuals than LP-LP individuals. In both experiments, LP individuals had the lowest body mass. Striped mice adjusted their behaviors in response to dietary protein levels. Protein deficiency reduced activity and stereotypic behavior and prevalence, possibly related to an energy or neurological deficit., (© 2017 Wiley Periodicals, Inc.)

It has often been proposed that bolder, more explorative or more active individuals also have a higher resting metabolic rate (RMR), indicating metabolic costs of these personality types. However, such individuals might often be restless and thus excluded from RMR datasets, leading to a significant sampling bias. We tested (1) whether such a bias occurs when animals are measured for a relatively common but short time period of 3h, and if so, (2) whether alternative measures of metabolic rate, that allow the incorporation of non-resting individuals, would reveal associations between metabolism and personality. For this, we studied free-living individuals of the African striped mouse (Rhabdomys pumilio) both during the moist season (N=25 individuals) with high food availability and the dry season (N=48 individuals) with low food availability. We assessed variation in the latency to explore a novel object, and the time spent active and time spent in the centre of a neutral arena. We examined links between personality and (i) RMR and (ii) four alternative metabolic rate (MR) metrics: average MR, highest MR, lowest MR and span of MR. Twenty-nine percent of the measured individuals had to be excluded from our RMR study because they remained restless during respirometry trials. Striped mice showed a behavioural syndrome where fast explorers also spent more time in centre and more time active than slow explorers. Individuals that did not rest during respirometry trials were faster explorers and in the moist season, they were also more active and spent more time in the centre than individuals that rested. We found no relationship between RMR and the behavioural syndrome, which might be due to the exclusion of individuals with a certain behavioural type, leaving a subset of compliant individuals. In the moist season, we found positive relationships between the behavioural syndrome and span of MR and lowest MR. In the dry season, low food availability may mask links between the behavioural syndrome and alternative MR measures due to reduced overall activity in striped mice. Our study demonstrated the importance to consider personality when measuring RMR and suggests that some alternative MRs may be useful to examine relationships between metabolism and personality when it is impossible to measure individuals over extended time periods., (Copyright © 2017 Elsevier Inc. All rights reserved.)

In response to variation in food availability and ambient temperature ( T a ), many animals show seasonal adaptations in their physiology. Laboratory studies showed that thyroid hormones are involved in the regulation of metabolism, and their regulatory function is especially important when the energy balance of an individual is compromised. However, little is known about the relationship between thyroid hormones and metabolism in free-living animals and animals inhabiting seasonal environments. Here, we studied seasonal changes in triiodothyronine (T 3 ) levels, resting metabolic rate (RMR) and two physiological markers of energy balance (blood glucose and ketone bodies) in 61 free-living African striped mice ( Rhabdomys pumilio ) that live in an semi-arid environment with food shortage during the dry season. We predicted a positive relationship between T 3 levels and RMR. Further, we predicted higher T 3 levels, blood glucose levels and RMR, but lower ketone body concentrations, during the moist season when food availability is high compared with summer when food availability is low. RMR and T 3 levels were negatively related in the moist season but not in the dry season. Both RMR and T 3 levels were higher in the moist than in the dry season, and T 3 levels increased with increasing food availability. In the dry season, blood glucose levels were lower but ketone body concentrations were higher, indicating a change in substrate use. Seasonal adjustments in RMR and T 3 levels permit a reduction of energy expenditure when food is scarce, and reflect an adaptive response to reduced food availability in the dry season., (© 2017. Published by The Company of Biologists Ltd.)

Dietary protein deficiency influences the behavioural phenotypes of mammals. We studied whether protein deficiency during gestation and/or post-weaning heightened anxiety, reduced memory recall and influenced competitive ability in the African striped mouse Rhabdomys dilectus chakae. Mice were subjected to five protein diet treatments, which they received continuously, or were raised on one diet to weaning and switched to an alternate diet post-weaning (Day 16): 1) HP-HP: high protein (24%); first letter pair indicates maternal diet and the second pair indicates offspring diet post-weaning; 2) BP-BP: baseline protein (19%); 3) LP-LP: low protein (10%); 4) HP-LP: switched from high to low protein diet; and 5) LP-HP: switched from low protein to high protein diet. From Day 70, when mice were sexually mature, 20 individuals (10 males, 10 females) per treatment were subjected to three successive experiments, in which we tested their anxiety responses in: 1) an open field arena (time spent in the centre of the open field); 2) novel object recognition (time spent exploring a novel object); and 3) social interactions (excluding BP-BP) in age-matched same-sex dyadic encounters (aggressive, amicable and avoidance behaviours). LP-LP and LP-HP treatment mice spent the least amount of time in the centre of the open field, did not demonstrate object preference compared to the other treatments, and were the most aggressive in dyadic encounters. Our study shows that the systemic effects of protein-deficient diets during early life shapes the behavioural phenotype in R. d. chakae, possibly through early organisation of neuro-biological pathways or competition among littermates., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Elevated risk of disease transmission is considered a major cost of sociality, although empirical evidence supporting this idea remains scant. Variation in spatial cohesion and the occurrence of social interactions may have profound implications for patterns of interindividual parasite transmission. We used a social network approach to shed light on the importance of different aspects of group-living (i.e. within-group associations versus physical contact) on patterns of parasitism in a neotropical primate, the brown spider monkey (Ateles hybridus), which exhibits a high degree of fission-fusion subgrouping. We used daily subgroup composition records to create a 'proximity' network, and built a separate 'contact' network using social interactions involving physical contact. In the proximity network, connectivity between individuals was homogeneous, whereas the contact network highlighted high between-individual variation in the extent to which animals had physical contact with others, which correlated with an individual's age and sex. The gastrointestinal parasite species richness of highly connected individuals was greater than that of less connected individuals in the contact network, but not in the proximity network. Our findings suggest that among brown spider monkeys, physical contact impacts the spread of several common parasites and supports the idea that pathogen transmission is one cost associated with social contact., (© 2015 The Author(s) Published by the Royal Society. All rights reserved.)

The level of dietary protein determines the onset of reproduction, affects offspring growth and maturation, and hence influences life-history traits and fitness. However, to date, the long-term life-history consequences of protein deficiency are not well understood. We studied the transgenerational effects of different levels of dietary protein on the life-history and level of maternal behavior of the striped mouse Rhabdomys dilectus chakae in captivity. Breeding pairs were assigned to three treatments based on the percentage of dietary protein: baseline (BP; 19%); high protein (HP; 24%); and low protein (LP; 10%). Reproductive output and offspring ontogeny was diminished in the LP treatment compared to the other treatments. Transgenerational effects were studied by breeding F2 females raised on the LP or HP diets on the same (HP-HP, LP-LP) or altered diets (HP-LP, LP-HP). The LP-LP treatment had no reproductive success, while reproductive capacity in the remaining treatments was determined mainly by the diet of mothers at breeding. Pups from protein-restricted females (LP, HP-LP) showed post-weaning compensatory growth. Timing of sexual maturity was age-dependent in female and mass-dependent in male offspring. Females fed low protein diets during breeding (LP, HP-LP) displayed lower levels of maternal behavior than females from the other treatments. This study demonstrates that the level of dietary protein influences the life-history of R. d. chakae in predictable ways. The taxon responds to changes in dietary protein at breeding, largely regardless of its nutrition during rearing. Such phenotypic flexibility in life-history parameters allows Rhabdomys to adaptively respond to unpredictable environmental changes., (© 2015 Wiley Periodicals, Inc.)

Numerous animal species currently experience habitat loss and fragmentation. This might result in behavioral and dietary adjustments, especially because fruit availability is frequently reduced in fragments. Food scarcity can result in elevated physiological stress levels, and chronic stress often has detrimental effects on individuals. Some animal species exhibit a high degree of fission-fusion dynamics, and theory predicts that these species reduce intragroup feeding competition by modifying their subgroup size according to resource availability. Until now, however, there have been few studies on how species with such fission-fission dynamics adjust their grouping patterns and social behavior in small fragments or on how food availability influences their stress levels. We collected data on fruit availability, feeding behavior, stress hormone levels (measured through fecal glucocorticoid metabolites (FGCM)), subgroup size, and aggression for two groups of brown spider monkeys (Ateles hybridus) in a small forest fragment in Colombia and examined whether fruit availability influences these variables. Contrary to our predictions, spider monkeys ranged in smaller subgroups, had higher FGCM levels and higher aggression rates when fruit availability was high compared to when it was low. The atypical grouping pattern of the study groups seems to be less effective at mitigating contest competition over food resources than more typical fission-fusion patterns. Overall, our findings illustrate that the relationship between resource availability, grouping patterns, aggression rates, and stress levels can be more complex than assumed thus far. Additional studies are needed to investigate the long-term consequences on the health and persistence of spider monkeys in fragmented habitats., (© 2014 The Authors. American Journal of Primatology Published by Wiley Periodicals, Inc.)

Non-invasive methods to assess stress hormone output via fecal glucocorticoid metabolites (FGCMs) have become a powerful tool in behavioral studies and conservation biology because they allow exploring the link between behavior, an animal's socio-ecological environment and its adrenocortical activity. However, FGCM levels are influenced by numerous other factors which often confound their interpretation. Thus, before applying these methods, knowledge on the impact of these factors is important. In this study we investigated the effect of (1) time of day, (2) age, (3) sex and (4) female reproductive state on FGCM levels in brown spider monkeys (Ateles hybridus) and red howler monkeys (Alouatta seniculus). Initially, we validated a 11β-hydroxyetiocholanolone enzyme immunoassay for monitoring the physiological stress response via fecal analysis in both species. We determined FGCM levels in fecal samples collected from two and six groups of wild spider monkeys (n=461 samples) and howler monkeys (n=166 samples), respectively. Our analyses revealed a strong effect of time of day on FGCM levels in spider monkeys, but no effect in howler monkeys. Adults of both species had significantly higher FGCM levels than subadults. In neither of the two species we found a sex-effect on FGCM output. Reproductive condition strongly affected FGCM levels in female spider monkeys which showed increasing concentrations with progressing gestation. This was not investigated in female howler monkeys due to an insufficient sample size. Our data indicate that the influence of the tested factors on fecal glucocorticoid metabolite output is species-specific, and that these variables need to be considered when interpreting FGCM levels in the species., (Copyright © 2013 The authors. Published by Elsevier Inc. All rights reserved.)

Interspecific aggression amongst nonhuman primates is rarely observed and has been mostly related to scenarios of resource competition. Interspecific infanticide is even rarer, and both the ultimate and proximate socio-ecological factors explaining this behavior are still unclear. We report two cases of interspecific infanticide and five cases of interspecific infant-directed aggression occurring in a well-habituated primate community living in a fragmented landscape in Colombia. All cases were initiated by male brown spider monkeys (Ateles hybridus) and were directed toward infants of either red howler monkeys (Alouatta seniculus: n = 6 cases) or white-fronted capuchins (Cebus albifrons: n = 1 case). One individual, a subadult spider monkey male, was involved in all but one case of interspecific infanticide or aggression. Other adult spider monkeys participated in interspecific aggression that did not escalate into potentially lethal encounters. We suggest that competition for food resources and space in a primate community living in high population densities and restricted to a forest fragment of ca. 65 ha might partly be driving the observed patterns of interspecific aggression. On the other hand, the fact that all but one case of interspecific infanticide and aggression involved the only subadult male spider monkey suggests this behavior might either be pathological or constitute a particular case of redirected aggression. Even if the underlying principles behind interspecific aggression and infanticide are poorly understood, they represent an important factor influencing the demographic trends of the primate community at this study site., (© 2012 Wiley Periodicals, Inc.)