Reproductive endocrinology, morphological traits, and sexual selection in a population of wild South African giraffes.

Sex steroids are pervasive in mammals and evolutionarily conserved, but differences in the nuances of endocrine profiles characterize distinct species. Two sex steroids, testosterone and progesterone, feature prominently in the life history of mammalian taxa, but neither one has been analyzed from wild giraffes. Our study was designed to address this gap in knowledge by examining how these sex steroids are related to biological features and giraffe life history. We conducted the research at Rooipoort Nature Reserve a 44,000 ha private nature reserve in South Africa on a population of South African giraffes (Giraffa camelopardalis giraffa). Eleven adult giraffe cows and seven adult bulls were immobilized and various biological samples and morphological measurements were obtained. We analyzed both testosterone and progesterone using Ultra High Performance Liquid Chromotography - Tandem Mass Spectrometry (UHPLC-MS/MS). We found that non-pregnant females had lower progesterone concentrations than pregnant females and that those in the last trimester of pregnancy showed a slight drop in progesterone, as well as an increase in testosterone. Among males, chronological age was correlated with testicle size, testosterone concentrations, and ossicone volume. We propose that the progesterone decline functions partly to accelerate resumption of ovulation because giraffes become pregnant while lactating, and that the testosterone elevation provides an endocrine mileu for female defense of neonatal calves, given that lion predation is a major threat to calf survival. We suggest that male reproductive strategies are mediated by the age-related impacts of testosterone on growth in both body mass and ossicone volume as a consequence of sexual selection. We conclude by noting that the robust and solid ossicones of male giraffes function in mate competition as wedges that are used to topple opponents by raising their legs and placing them in an off-balanced position that can seriously injure them when falling to the ground.

Reducing stress and stereotypic behaviors in captive female pygmy slow lorises (Nycticebus pygmeaus).

Improving captive conditions of pygmy slow lorises (Nekaris and Nijman have recently suggested that the pygmy slow loris should be called the pygmy loris and is distinctive enough to warrant a new genus, Xanthonycticebu) (Nycticebus pygmeaus) poses many challenges because detailed aspects of their lives in the wild are incomplete. This hinders efforts to replicate sustainable environments for them. To improve their well-being in captivity, eight rescued female pygmy slow lorises at the Japan Monkey Center (JMC) were socially housed in two types of groups following their solitary housing: two pairs and one group of four individuals. They spent much of their time in affiliative behaviors, as well as sharing sleeping sites after placement in a social group. The purpose of my study was to examine whether social housing helped in reducing stress by comparing fecal glucocorticoids and stereotypic behaviors when housed alone and when with conspecifics. Overall, the levels of fecal glucocorticoids were significantly lower when socially housed than when kept alone. One individual exhibited stereotypic behavior when housed alone, but this behavior disappeared after social housing. These findings support recent evidence that pygmy slow lorises are social animals and will benefit from group housing in captivity. We conclude that social housing of pygmy slow lorises improves their well-being by reducing stress levels, and that their group housing in captivity can provide dividends for the conservation of this endangered nocturnal primate because lorises intended for release should find it easier to adapt to natural conditions.

Costs and benefits of living in a vegetated, compared with non-vegetated, enclosure in male Japanese macaques (Macaca fuscata).

Improving captive environments for primates has been an important tool to enhance animal welfare. One method has been to provide primates with naturalistic vegetated enclosures to promote species-specific behaviors, enhancing interactions with their social and natural environment, such as an increase in feeding, foraging, and positive social behaviors such as play. To investigate the benefits in which living in naturalistic environments promote general animal well-being, we observed immature and adult males living in two outdoor housed groups of Japanese macaques (Macaca fuscata) in the Kyoto University Primate Research Institute (KUPRI), Inuyama, Japan, from June of 2015 until June 2016. One enclosure was naturally vegetated and the other was not. We recorded male activity budgets, affiliative (groom, play) behaviors, and rates of agonistic interactions. To examine health status, we recorded and compared coat conditions for both groups. We found that males in the vegetated enclosure spent more time in social play than males in the non-vegetated enclosure, while males in the non-vegetated enclosure displayed more stereotypic behaviors and agonistic interactions. We recorded better coat conditions in the vegetated enclosure males while rates of social grooming or self-grooming were no different between males in the two enclosures. The males in the vegetated enclosure did not have activity budgets more similar to their wild counterparts; but they spent more time in feeding-related activities and less time resting, which was more similar to their wild counterparts than males in the non-vegetated enclosure. Our findings suggest that individuals housed in naturalistic environments have significantly greater behavioral and physical markers of wellbeing than those housed in unnatural, large outdoor enclosures. Although we found that males in both types of enclosures overall had similar time budgets to males in the wild, the detailed behavioral and health results suggest that the welfare benefits to males were greater in the vegetated enclosure, compared with non-vegetated enclosures. Efforts to mimic more natural environments should promote the well-being of primates.

Behavioral Changes of Solitary Housed Female Pygmy Slow Lorises (Nycticebus pygmeaus) after Introduction into Group Enclosures.

Pygmy slow lorises (Nycticebus pygmaeus) are threatened with extinction in the wild. Their nocturnal lifestyle and small size make them difficult to study in their natural habitat, but increasing evidence suggests that they are more social than previously thought. Our study was designed to assess the sociability of pygmy slow lorises by transferring six adult females from solo cages into environmentally enriched group home cages at the Japan Monkey Centre's Slow Loris Conservation Centre. Two females were paired to create one group, while the other four were placed together in a second group. We compared their social interactions, activity budgets, and postural behaviors before and after social housing was initiated. We found that all-female slow loris groups had a high degree of sociality, preferred to stay close to each other, nested together every night, and spent less time in locomotion and more time grooming than when living alone. These results suggest that female pygmy slow lorises actively seek companions when available. The captive housing of all-female groups of lorises could lead to better husbandry practices and improved animal welfare by allowing them to have conspecific companions. We conclude that isosexual groups of pygmy slow lorises should be preferred over single housing when possible.

The impact of Masai giraffe nursery groups on the development of social associations among females and young individuals.

Fission-fusion social systems involve the splitting and merging of subgroups with frequent changes in membership occurring as a result of a number of ecological and social factors, such as demographic processes including birth, movement, or death. Giraffe reside in fission-fusion social systems, and we studied how reproductive status influence associations among females, as well as how associations differ between calves and juveniles. Data were collected in Katavi National Park, Tanzania, during five study periods. We used social network analysis to identify whether reproductive status and developmental stages predict differences in giraffe social association. We found that females with offspring maintain stronger associations than females without offspring. We also revealed that calves and juveniles had similar network association patterns. Our results suggest that the presence of dependent offspring influences the social associations of females and individuals less than 1.5 years of age are still maintaining strong social associations with nursery group members. We conclude that nursery groups among giraffe are co-operative rearing units that probably reduce the costs of rearing to mothers, and may provide a group structure for animals to begin to develop skills useful for their future life in a fission-fusion social system.

Changes in social behavior and fecal glucocorticoids in a Japanese macaque (Macaca fuscata) carrying her dead infant.

Maternal care towards dead infants has been observed in many wild and captive mammals, but the consequences of this behavior for social interactions and the physiological status of the mother remain elusive. Here, we report changes in rates of aggression and grooming time, and fecal glucocorticoid (fGC) levels in a free-ranging female Japanese macaque (Macaca fuscata) that carried her dead infant for 20 days. Our observations revealed that when carrying the dead infant, the mother showed increased rates of grimace, avoidance, and human-directed behaviors, along with reduced allogrooming time and fleeing from other individuals. Postpartum fGC levels were comparable to those of non-pregnant and non-lactating females, suggesting that the energetic costs and stress of carrying a dead infant are low. Our findings indicate that carrying a dead neonate can have three profound consequences on the mother: increased fearful behavior, decreased allogrooming, and a rapid return to baseline fGC levels. We hypothesize that dead infant-carrying may have evolved as a strategy to mitigate stress from infant loss. These findings have implications for our understanding of grief in nonhuman primates and can impact management protocols surrounding deaths in captive social groups.

A comparative perspective on the evolution of mammalian reactions to dead conspecifics.

In a variety of mammalian species, mothers and others care for and/or carry deceased newborns, and sometimes other conspecifics. The rationale for such behavior remains elusive. Based upon field observations of olive baboon (Papio anubis), African elephant (Loxodonta africana), and Thornicroft's giraffe (Giraffa camelopardalis) responses to recently dead conspecifics, combined with reports in the literature, a hypothesis is proposed to account for this activity. Among female mammals, lifetime reproductive success is more dependent upon rearing, than production, of offspring. The successful nurturing of progeny is associated with a strong maternal-offspring bond. One of the most important chemicals involved in both lactation and mother-infant bonding is oxytocin, a tiny molecule that has a lengthy evolutionary history and is implicated in the formation of social bonds across mammals. Evolution has extended the impact of oxytocin by adopting it beyond the original mother-infant bond to the establishment of social bonds that are required among group-living animals. Hence, sociality is a consequence of the same fundamental biological mediator of mother-offspring bonding, and this intricate connection between physiology and behavior has produced a situation where sometimes animals will care for or carry dead companions. Ways to test this hypothesis, as well as a potential way to refute it, are proposed.

Developmental changes in the endocrine stress response in orangutans (Pongo pygmaeus).

Non-invasive measures of stress are crucial for captive and conservation management programs. The adrenal hormone dehydroepiandrosterone-sulfate (DHEAS) has recently been adopted as a stress marker, but there is little investigation of its relationship to glucocorticoids (GC), well-known indicators of stress. This study examined the influence of age, reproductive state and environment on GC and DHEAS levels in orangutans, to test whether the GC/DHEAS ratio can provide an index of stress response in primates. We measured fecal GC (fGC) and fecal DHEAS (fDHEAS) concentrations in 7 captive orangutans from zoological parks in Japan and 22 wild orangutans from Danum Valley Conservation Area, Malaysia. We found that in a stressful condition (transportation), fDHEAS levels increased 2 days after the fGC response, which occurred 1 day after the stressor. One pregnant female had elevated levels of both hormones, and a higher fGC/fDHEAS ratio than baseline. Females in the first year of lactation had fGC levels and the fGC/fDHEAS ratio significantly higher than both baseline and females in the second and subsequent years of lactation. There was no effect of age on fGC levels, but the fGC/fDHEAS ratio was higher in infants than adults and adolescents. fDHEAS concentrations were lower in infants than juveniles, adolescents and adults, a phenomenon known as adrenarche, shared with humans and other great apes. We suggest that changes in DHEAS during orangutan life history are associated with changes in the dynamics of maintaining homeostasis that vary with age and reproductive state. The GC/DHEAS ratio index is useful to evaluate age-related abilities of responding to stressful challenges.

Salivary alpha-amylase enzyme is a non-invasive biomarker of acute stress in Japanese macaques (Macaca fuscata).

Salivary alpha-amylase (sAA) enzyme functions as a digestive enzyme in many species that consume starch in their diet. Human studies have also revealed that sAA enzyme activity levels are positively correlated with the release of the stress hormone norepinephrine, allowing sAA to act as a biomarker for sympathetic nervous system activity. Recent non-human primate studies have incorporated sAA as a physiological stress marker. However, no published reports have investigated the time course of sAA from a stressful event to return to baseline levels in non-human primates. Furthermore, no validation of sAA as a stress biomarker has been reported for Japanese macaques (Macaca fuscata). This study had two primary aims: (1) to develop a systematic method for non-invasive saliva collection and, (2) to investigate sAA as a biomarker of acute stress in M. fuscata in order to better understand its acute stress-related characteristics. We developed a non-invasive method for cooperative saliva collection using positive reinforcement training (PRT) and tracked individual progress over 595 trials in ten individually housed Japanese macaques. We detected sAA enzyme in M. fuscata via kinetic reaction assay, then performed 22 acute stress tests. Four tests met conditions for interpreting sAA in response to an acute stressor and these results show that on average sAA activity rapidly increased post-stressor (mean ± SD = 4.2 ± 0.9 min) and returned to baseline shortly thereafter (10.4 ± 0.6 min). Our report reveals for the first time the temporal dynamics of sAA when applying acute stress to Japanese macaques and could be a useful tool for assessing animal welfare.

Beneficial effect of hot spring bathing on stress levels in Japanese macaques.

The ability of animals to survive dramatic climates depends on their physiology, morphology and behaviour, but is often influenced by the configuration of their habitat. Along with autonomic responses, thermoregulatory behaviours, including postural adjustments, social aggregation, and use of trees for shelter, help individuals maintain homeostasis across climate variations. Japanese macaques (Macaca fuscata) are the world's most northerly species of nonhuman primates and have adapted to extremely cold environments. Given that thermoregulatory stress can increase glucocorticoid concentrations in primates, we hypothesized that by using an available hot spring, Japanese macaques could gain protection against weather-induced cold stress during winter. We studied 12 adult female Japanese macaques living in Jigokudani Monkey Park, Japan, during the spring birth season (April to June) and winter mating season (October to December). We collected faecal samples for determination of faecal glucocorticoid (fGC) metabolite concentrations by enzyme immunoassay, as well as behavioural data to determine time spent in the hot springs, dominance rank, aggression rates, and affiliative behaviours. We used nonparametric statistics to examine seasonal changes in hot spring bathing, and the relationship between rank and air temperature on hot spring bathing. We used general linear mixed-effect models to examine factors impacting hormone concentrations. We found that Japanese macaques use hot spring bathing for thermoregulation during the winter. In the studied troop, the single hot spring is a restricted resource favoured by dominant females. High social rank had both costs and benefits: dominant females sustained high fGC levels, which were associated with high aggression rates in winter, but benefited by priority of access to the hot spring, which was associated with low fGC concentrations and therefore might help reduce energy expenditure and subsequent body heat loss. This unique habit of hot spring bathing by Japanese macaques illustrates how behavioural flexibility can help counter cold climate stress, with likely implications for reproduction and survival.

Effect of castration on social behavior and hormones in male Japanese macaques (Macaca fuscata).

Population control is essential for animal welfare and human safety in free-ranging or captive settings, especially when resources are limited. As an alternative to lethal control, contraceptive methods such as castration in males can be a practical solution, because the testicles are a visual cue to determine which males have been sterilized. However, careful analyses should be carried out to ensure no disruption in the social structure of the population. Japanese macaques (Macaca fuscata) live in a society centered around dominance rank and matrilineal kin relationships. Testosterone and glucocorticoids have been correlated with dominance rank in humans and other species, but previous studies in Japanese macaques were inconclusive. This study aimed to investigate behavioral and physiological differences between castrated and intact male Japanese macaques, and to examine the effect of season and behavior in hormonal concentrations in intact males. Our subjects were six intact males from Jigokudani Monkey Park (Japan) and 13 castrated males from Born Free Primate Sanctuary (USA). We collected behavioral data using both focal and ad libitum sampling, and fecal samples for determination of testosterone (fT) and glucocorticoids (fGC) by enzyme immunoassay. We found that castrated males exhibited a social hierarchy, but not a linear hierarchy, as was the case in intact males. Castrated males were less aggressive than intact males, probably because fT concentrations were lower in the castrated males. Age was positively correlated with fGC levels, while fT concentrations were lower in old males than younger adult males. Fecal T levels correlated with both rank and atmospheric temperature. In intact males, both fGC and fT levels were elevated during the mating season. We found a negative correlation between fGC levels and the amount of grooming received. Our findings indicate that castration had a minimal impact on sociality, with season, temperature, and rank all influencing male sex steroid levels in intact males. Our study indicates that castration can be adopted as a population control mechanism without drastically altering the social relationships of males.

How many species of giraffe are there?

In a recent paper in Current Biology, Fennessy and colleagues [1] conclude that there are four species of giraffe and that their numbers are declining in Africa. Giraffes (Giraffa camelopardalis) are presently classified as one species, with nine subspecies, which are considered 'Vulnerable' on the IUCN Red List [2]. The present consensus of one species divided into nine subspecies has previously been questioned (Supplemental information), and Fennessy and colleagues [1] provide another viewpoint on giraffe taxonomy. The fundamental reason for different taxonomic interpretations is that they are based upon different datasets that adopt different statistical techniques and follow different criteria for nomenclature.

Daylight saving time can decrease the frequency of wildlife-vehicle collisions.

Daylight saving time (DST) could reduce collisions with wildlife by changing the timing of commuter traffic relative to the behaviour of nocturnal animals. To test this idea, we tracked wild koalas (Phascolarctos cinereus) in southeast Queensland, where koalas have declined by 80% in the last 20 years, and compared their movements with traffic patterns along roads where they are often killed. Using a simple model, we found that DST could decrease collisions with koalas by 8% on weekdays and 11% at weekends, simply by shifting the timing of traffic relative to darkness. Wildlife conservation and road safety should become part of the debate on DST.

Dead or alive? Predicting fetal loss in Japanese macaques (Macaca fuscata) by fecal metabolites.

Dehydroepiandrosterone-sulfate (DHEAS) is the main steroid product of the primate fetal adrenal during mid to late gestation and it plays a major role in providing estrogens needed for parturition. We tested the hypothesis that this hormone can indicate fetal health status and attempted to use fecal DHEAS (fDHEAS) to predict pregnancy outcome in Japanese macaques. The subjects were 16 adult females and 3 neonatal Japanese macaques living in captivity at the Primate Research Institute, Kyoto University. We classified females that gave birth to healthy infants as successful and females that gave birth to dead infants as stillbirth (late fetal loss) and miscarriage (early fetal loss). The remaining females did not become pregnant and were used as controls. We collected fecal samples from all cycling, pregnant, and post-pregnant females as well as the three neonates for analysis of fDHEAS, fecal estrogen (fE) and fecal progesterone (fP) by enzyme immunoassay. We found that fE and fP increased during gestation in both successful and stillbirth groups, but increased only during the first two months in the female that had a miscarriage. Levels of fDHEAS only increased in the second half of gestation in successful pregnancies. Neonates had extremely elevated concentrations of fDHEAS in comparison to post-parturition females, which confirms that DHEAS metabolites are a product of the fetal adrenal. Low DHEAS levels could be a marker of an unsuccessful pregnancy in primates. Monitoring fDHEAS levels can be useful in zoos and institute management and can be applied to wild and free-ranging populations.

Genetic studies on the Cayo Santiago rhesus macaques: A review of 40 years of research.

Genetic studies not only contribute substantially to our current understanding of the natural variation in behavior and health in many species, they also provide the basis of numerous in vivo models of human traits. Despite the many challenges posed by the high level of biological and social complexity, a long lifespan and difficult access in the field, genetic studies of primates are particularly rewarding because of the close evolutionary relatedness of these species to humans. The free-ranging rhesus macaque (Macaca mulatta) population on Cayo Santiago (CS), Puerto Rico, provides a unique resource in this respect because several of the abovementioned caveats are of either minor importance there, or lacking altogether, thereby allowing long-term genetic research in a primate population under constant surveillance since 1956. This review summarizes more than 40 years of genetic research carried out on CS, from early blood group typing and the genetic characterization of skeletal material via population-wide paternity testing with DNA fingerprints and short tandem repeats (STRs) to the analysis of the highly polymorphic DQB1 locus within the major histocompatibility complex (MHC). The results of the paternity studies also facilitated subsequent studies of male dominance and other factors influencing male reproductive success, of male reproductive skew, paternal kin bias, and mechanisms of paternal kin recognition. More recently, the CS macaques have been the subjects of functional genetic and gene expression analyses and have played an important role in behavioral and quantitative genetic studies. In addition, the CS colony has been used as a natural model for human adult-onset macular degeneration, glaucoma, and circadian rhythm disorder. Our review finishes off with a discussion of potential future directions of research on CS, including the transition from STRs to single nucleotide polymorphism (SNP) typing and whole genome sequencing.

Environmental, biological, and social factors influencing fecal adrenal steroid concentrations in female Japanese macaques (Macaca fuscata).

The ability to determine hormonal profiles of primate populations using non-invasive techniques can help to monitor physical fitness, stress, and physiological responses to environmental changes. We investigated fecal glucocorticoids (fGC) and DHEAS concentrations in captive Japanese macaques (Macaca fuscata) in relation to environmental, biological, and social factors. The subjects were female Japanese monkeys from 4 months to 31 years old housed in captivity (27 in social groups and 12 in single cages). Fecal samples were collected from all females, and behavioral data from the social groups during the mating season and the following birth season. Hormonal concentrations were analyzed by enzyme immunoassay. Our results revealed that both fGC and fecal DHEAS concentrations are higher in females housed indoors in single cages than in those living outdoors in social groups. We also found that fGC concentrations were higher in the cycling females during the mating (winter) season than the lactating females in the birth (spring) season. Age was negatively associated to both fGC and fecal DHEAS levels, but the relationship between age and fecal DHEAS was more evident in females housed indoors in single cages than in females housed in outdoor social groups. We did not observe any association of dominance rank with either fecal DHEAS or fGC. This study showed that measurement of fecal DHEAS and fGC can be a good method to assess stress in Japanese macaques. These findings provide insights about the physiology of these two adrenal hormones in female Japanese macaques, which can be applied to wild populations and is fundamental for captive management and conservation biology.

The influence of age and season on fecal dehydroepiandrosterone-sulfate (DHEAS) concentrations in Japanese macaques (Macaca fuscata).

Dehydroepiandrosterone (DHEA) and its sulfate, DHEAS, are the most abundant steroid hormones in primates, providing a large reservoir of precursors for the production of androgens. DHEAS levels decline with age in adult humans and nonhuman primates, prompting its consideration as a biomarker of senescence. However, the mechanisms responsible for this age-related decrease and its relationship to reproduction remain elusive. This research investigated DHEAS concentrations in fecal samples in order to determine age-related changes in captive Japanese macaques, as well as to assess the possible influence of seasonality. The subjects were 25 female Japanese macaques (2weeks to 14years-old) housed outdoors in social groups at the Primate Research Institute. We collected three fecal samples from each animal during the breeding season (October to December) and three additional samples from adult females during the non-breeding season (May to June). The hormonal concentrations were determined using enzyme immunoassay. DHEAS concentration was negatively correlated with age, but we did not find a significant difference between breeding and non-breeding seasons. Neonatal macaques had the highest DHEAS concentrations of all age groups. We suggest that elevated neonatal DHEAS is possibly a residue from fetal adrenal secretion and that, as in humans, it might assist in neurobiological development.

Fat-soluble vitamin and mineral comparisons between zoo-based and free-ranging koalas (Phascolarctos cinereus).

As part of a health investigation on koalas at San Diego Zoo, serum samples were analyzed from 18 free-ranging and 22 zoo-based koalas, Phascolarctos cinereus. Serum concentrations of calcium, chloride, cobalt, copper, iron, magnesium, manganese, molybdenum, phosphorus, potassium, selenium, sodium, zinc, and vitamins A, E, and 25(OH)D3 were quantified. Calcium, chloride, molybdenum, selenium, and vitamin E concentrations were significantly higher in zoo-based koalas than in free-ranging koalas, whereas magnesium, manganese, phosphorus, and zinc concentrations were significantly higher in the free-ranging koalas. No significant differences were found between genders. The results from this study will help to establish a starting point for determining target circulating nutrient concentrations in koalas.

Estimating daily walking distance of captive African elephants using an accelerometer.

Two central concerns for elephant husbandry and management are whether zoological enclosures are appropriately sized and the degree to which naturalistic exercise and activity are observed in such enclosures. In order to address these issues, accurate data on the daily walking distance of elephants both in situ and ex situ are necessary. We used an accelerometer, a pedometer that measures step count and activity level, to estimate walking distance in African elephants (Loxodonta africana) at the San Diego Zoo's Wild Animal Park. The accelerometer was worn simultaneously with a GPS unit that recorded actual walking distance. Estimates of walking distance were extrapolated from the accelerometer and compared with actual distances determined by GPS data. The accelerometer was found to overestimate step count, and subsequently walking distance, by including false counts of steps. Extrapolating walking distance based upon stride length measurements did not match actual GPS walking distance. However, activity level output from the accelerometer significantly correlated with actual GPS walking distance. In addition, we report that the rate of movement is comparable to that reported in other zoological settings. We provide a linear regression equation that can be utilized by other institutions to estimate daily walking distance of elephants in their collection who are outfitted with accelerometers.