Glucocorticoids of bison bulls in relation to social status

A primary response to stress is an increase in circulating adrenal glucocorticoids (GC) such as cortisol. Two hypotheses propose differential stress responses to agonistic and aggressive interactions in social groups. If subordinate animals are subjected to social and psychological stressors leading to chronic GC elevation, the 'stress of subordination' hypothesis predicts that GCs will be higher in subordinates than dominants. Alternatively, if dominant animals are subject to physiological stressors (e.g., fight at higher rates than subordinates) or hierarchies are unstable, the 'stress of domination' hypothesis predicts higher GCs in dominant individuals. Both models predict that GC levels will peak during the breeding season. We tested these predictions in bison bulls (Bison bison) using fecal steroid analysis to characterize GC concentration and behavioral observations to determine dominance rank, copulatory success, and tending status of bulls. Fecal samples were collected during 2003 from adult bison bulls during pre-rut (June), rut (July-August), and post-rut (September). Matched sample data indicated that mean GC levels (ng/g feces) of bulls strongly peaked during the 4-week rut, doubling from pre-rut to rut and then declining again during post-rut. High ranked dominant bulls maintained higher GC levels than lower ranked subordinate bulls. Dominance rank was positively correlated with copulatory success and age, and dominant bulls were more likely to tend (guard) cows as they approached estrus. There was a positive correlation between GC level and copulatory success, with prime-aged bulls (> or =7 years) obtaining the most copulations. GC levels were positively correlated with bull androgen levels determined in a previous study. These results support the 'stress of domination' hypothesis, indicating that dominant bison bulls pay a significant physiological price for high social status and the opportunity to mate.     

不同年龄雄性北山羊发情期时间分配特征

前人研究表明,可多次繁殖的反刍物种其雄性个体在发情期采食时间显著减少。目前有两个假说解释这一现象,即能量摄入最大化假说和能量保存假说。为验证雄性北山羊在不同发情阶段所采取的能量保存策略,作者于2014年10-12月在新疆天山中部采用焦点动物取样法采集数据,采用Kruskal-Wallis检验和Spearman秩相关性检验分析数据。研究发现雄性北山羊成体和亚成体发情期采食时间均显著低于发情前期和发情后期,但二者在不同发情阶段卧息时间无显著变化,发情期采食和卧息时间比亦显著降低。发情期发情行为时间显著高于发情前期和发情后期,非发情时间主要用于采食。发情期采食时间和卧息时间都与发情行为时间呈显著的负相关关系。雌性北山羊发情期采食时间亦显著低于发情前期和发情后期,发情期和发情后期卧息时间显著高于发情前期。本研究结果表明,发情期不同年龄阶段雄羊都主要采取能量摄入最大化策略,但同时也具有部分能量保存策略的特征。     

Season effect on genitalia and epididymal sperm from Iberian red deer, roe deer and Cantabrian chamois

Seasonality deeply affects the physiology and behavior of many species, and must be taken into account when biological resource banks (BRBs) are established. We have studied the effect of seasonality on many reproductive parameters of free-ranging Iberian red deer, roe deer and Cantabrian chamois, living in Spain. Testicles from hunted animals were collected and sent to our laboratory at different times during the year. We recorded the weight and volume of testis, the weight of the epididymis and its separate parts (caput, corpus, and cauda), the weight of the sperm sample collected from the cauda epididymis, and several sperm parameters (sperm concentration, spermatozoa recovered, motility, HOS test reactivity, acrosomal status, and viability). We studied the data according to several periods, defined accordingly to each species. For red deer, we defined rut (mid-September to mid-October), post-rut (mid-October to mid-December), and non-breeding season (February). For roe deer, they were pre-rut (June), rut (July), post-rut (first fortnight of August), and non-breeding season (September). For chamois: non-breeding season (June to mid-September) and breeding season (October-November). The rut/breeding season yielded significantly higher numbers for almost all parameters. However, in the case of red deer, sperm quality was higher in the post-rut. For roe deer, testicular weight was similar in the pre-rut and in the rut, and sperm quality did not differ significantly between these two periods, although we noticed higher values in the rut. In the case of chamois, sperm quality did not differ significantly from the breeding season, but data distribution suggested that in the non-breeding season there are less males with sperm of good quality. On the whole, we find these results of interest for BRB planning. The best season to collect sperm in this species would be the breeding season. However, post-rut in red deer, pre-rut in roe deer, and non-breeding season in chamois could be used too, because of the acceptable sperm quality, despite the lower quantity salvaged. More in-depth research needs to be carried out on the quality of sperm salvaged at different times of the year in order to confirm these findings.     

Individual Facial Coloration in Male <Emphasis Type="Italic">Eulemur fulvus rufus</Emphasis>: A Condition-dependent Ornament?

Researchers studying individual variation in conspicuous skin coloration in primates have suggested that color indicates male quality. Although primate fur color can also be flamboyant, the potential condition dependence and thus signaling function of fur remains poorly studied. We studied sources of variation in sexually dichromatic facial hair coloration in red-fronted lemurs (Eulemur fulvus rufus). We collected data on 13 adult males in Kirindy Forest, Madagascar, during two study periods in 2006 and 2007, to determine whether variation in facial hair coloration correlates with male age, rank, androgen status, and reproductive success. We quantified facial hair coloration via standardized digital photographs of each male, assessed androgen status using fecal hormone measurements, and obtained data on reproductive success through genetic paternity analyses. Male facial hair coloration showed high individual variation, and baseline coloration was related to individual androgen status but not to any other parameter tested. Color did not reflect rapid androgen changes during the mating season. However, pronounced long-term changes in androgen levels between years were accompanied by changes in facial hair coloration. Our data suggest that facial hair coloration in red-fronted lemur males is under proximate control of androgens and may provide some information about male quality, but it does not correlate with dominance rank or male reproductive success.     

Foraging time of rutting bighorn rams varies with individual behavior, not mating tactic

Mate guarding is the primary mating tactic used by dominantmales of many species of ungulates. Guarding males are thoughtto forage less during the rut than do nonguarding males, possiblyleading to greater fitness costs. I observed bighorn rams foragingduring the pre-rut and the rut. I compared how coursing (analternative mating tactic) and tending (a form of mate guarding)affected the foraging behavior of bighorn rams over the rut,to test whether foraging was more constrained by mate guardingthan by coursing. All adult males spent less time feeding duringthe rut compared with the pre-rut. The decrease in time spentfeeding, however, was independent of mating tactic. Contraryto expectation, individual rams observed both coursing and tendingspent less time foraging when coursing than when tending. Foryoung rams, the time spent in rutting activities was correlatedwith individual pre-rut mass, indicating that males either modifytheir behavior according to available metabolic reserves oradjust the energy devoted to rutting activities to the levelof expected benefits. Mate guarding does not appear to constrainforaging more than coursing. The costs of male reproductivebehavior may depend more upon individual effort than on theparticular tactic adopted.     

Seasonality of adult male Japanese macaques (Macaca fuscata): androgens and behavior in a confined troop

Seasonal variations in levels of serum testosterone, dihydrotestosterone (DHT), reproductive behavior, and social behavior were investigated in 12 adult males (5 to 20+ years of age) of the Oregon troop of Japanese macaques (Macaca fuscata). Blood samples were collected at 2- to 4-month intervals, and behaviors were monitored twice weekly over a 15-month period. Significant seasonal variations in levels of testosterone and DHT, and in frequencies of mount series, ejaculations, number of female partners, displays, courtship, and aggression were observed. Seasonal variations in reproductive and social behaviors did not correlate with seasonal variations in androgen levels because seasonal increases in these behaviors followed seasonal increases in the androgens with a 1- to 2-month delay. However, significant correlations between increased androgen levels and the onset of mating activity occur when mean monthly frequencies of mount series are shifted 1 to 2 months earlier to coincide with the rise in serum androgen levels. The frequency of adult male play and male-male mounting increased significantly when androgen levels were low. We suggest that photoperiod changes may function as a proximate cue in male Japanese macaques which induces a state of biological readiness for mating, and the behavioral consequences (i.e., mating) are then dependent upon the presence of receptive females.     

不同发情阶段雄性鹅喉羚的时间分配特征

以往研究表明受发情交配行为制约,一些雄性反刍动物在发情期食物摄入量明显降低。已有两个相关假说解释该现象:能量摄入最大化假说和能量保存假说。作者于2009 ～ 2010 年在卡拉麦里山有蹄类自然保护区研究了雄性鹅喉羚不同发情阶段的时间分配。结果表明雄羚发情期采食时间比例明显下降(37. 9% ),低于发情前期(63. 6% )和发情后期(65. 8% );发情期卧息时间比例(6. 0% )与发情后期相近(5. 4% ),明显低于发情前期(23.2% );发情前期至发情后期采食卧息时间比(分别为2. 7、6. 3、12. 1)显著增加;发情期雄羚站立和移动时间比例明显升高,采食行为时间占非发情行为时间主要部分(86. 4% ),且采食行为与发情行为显著相关。相比之下,雌羚不同发情阶段采食行为时间分配比例相似。总之,除必需投入的发情行为外,发情期雄羚最大化其能量摄入;发情行为的投入是导致发情期雄羚食物摄入量下降的主导因子,雄性能量摄入最大化假说更好地解释了发情期鹅喉羚所采取的能量策略。     

Seasonally of adult male japanese macaques (Macaca fuscata): Androgens and behavior in a confined troop

Seasonal variations in levels of serum testosterone, dihydrotestosterone (DHT), reproductive behavior, and social behavior were investigated in 12 adult males (5 to 20 + years of age) of the Oregon troop of Japanese macaques (Macaca fuscata). Blood samples were collected at 2- to 4-month intervals, and behaviors were monitored twice weekly over a 15-month period. Significant seasonal variations in levels of testosterone and DHT, and in frequencies of mount series, ejaculations, number of female partners, displays, courtship, and aggression were observed. Seasonal variations in reproductive and social behaviors did not correlate with seasonal variations in androgen levels because seasonal increases in these behaviors followed seasonal increases in the androgens with a 1- to 2-month delay. However, significant correlations between increased androgen levels and the onset of mating activity occur when mean monthly frequencies of mount series are shifted 1 to 2 months earlier to coincide with the rise in serum androgen levels. The frequency of adult male play and male-male mounting increased significantly when androgen levels were low. We suggest that photoperiod changes may function as a proximate cue in male Japanese macaques which induces a state of biological readiness for mating, and the behavioral consequences (i.e., mating) are then dependent upon the presence of receptive females.     

Fighting Tactics of Fallow Bucks (Dama dama,Cervidae): Reducing the Risks of Serious Conflict

Competition between male fallow deer (Dama dama), during the breeding season was studied to determine if conflict strategies were consistent with the reduction of risk. Agonistic interactions between males were analysed in relation to age, dominance rank and availability of mating opportunities. The breeding season was divided into two main periods: the pre-rut began when all males had cleaned the velvet from their antlers and ended on the last day before matings were first observed, while the rut refers to the period between the first and last matings. Overall, socially mature males (≥4yr old) were involved in more interactions than immature (≤3yr old) males. Males established dominance rank largely by non-contact agonistic interactions during the pre-rut and there was substantial carry-over of rank to the rut, when it was correlated with mating success. The mating success of males was skewed; mature males achieved 99.4% of the matings and immature males accounted for 0.6%. A mature male was 13 times more likely to fight than an immature male; the mature males that fought most often did so between 0.4 and 0.5 times per hour. During the rut, the number of fights was positively correlated across days with the number of matings. The majority of agonistic interactions (79%) comprising dyads of immature males, involved antler contact. In contrast, mature males engaged antlers in only 42% of their interactions. Fights between mature males lasted more than twice as long as those between immature males and were more likely to occur between opponents with similar dominance ranks. However, towards the end of the rut formerly mismatched opponents were more likely to fight. Thus males operated conditional competitive strategies to decide when to interact and fight. The persistence of rank order from the pre-rut period to the rut and the tendency for mature males to resolve disputes without antler contact, served to reduce the frequency of fights and therefore the risk of serious injury.     

Male competition and its hormonal correlates in Assamese macaques (Macaca assamensis)

In polygynous mammals, where males compete over access to females, the potential of males to monopolize reproductive females largely depends on the spatio-temporal distribution of reproductive females. We investigated mechanisms of male reproductive competition and its hormonal basis in a cercopithecine species with reduced contest potential owing to female reproductive synchrony and concealed ovulation. Over 16 months including two mating seasons we collected 1218 h of observational focal animal data and 1254 fecal samples of 11-12 adult and large subadult male Assamese macaques (Macaca assamensis) living in their natural habitat in Thailand. Androgen output along with aggressive behavior showed a seasonal pattern, with highest values being obtained by all males during the mating season and by those males experiencing acute social challenges, e.g. rank change and dispersal. Individual androgen levels and rates of attacks were linked across the study period, suggesting a promoting function of androgens for aggressive behavior. Dominance rank predicted neither mating success nor androgen levels consistently, indicating a reduced selective advantage of high social status for general mating access. However, high ranking males engaged in extended consortships with reproductive females. Distribution of consortships across males followed a priority of access distribution, with the two top ranking males accounting for 75% of consort activity, suggesting that high social status also carries fitness benefits in a species characterized by low contest potential.     

Contrasting Alternative Hypotheses to Explain Rut‐Induced Hypophagia in Territorial Male Chamois

Male ungulates in temperate environments often show a severe reduction in time spent foraging during the mating season. Several hypotheses have been put forward to explain this phenomenon but, so far, no study investigated the proximate mechanisms underlying rut‐induced hypophagia in ungulates using alternative mating tactics (AMTs). Between the pre‐rut and post‐rut of 2011 and 2012, we collected data on activity budgets, parasite burden and androgen levels of territorial and non‐territorial male Alpine chamois Rupicapra r. rupicapra in the Gran Paradiso National Park (Italy). We aimed to investigate whether AMTs showed similar reduction in time spent foraging during the mating period and to test the predictions underlying alternative hypotheses that may explain rut‐induced hypophagia. Only territorial males showed a significant reduction in time spent foraging during the rut; the lack of correlation between proportion of time spent foraging and androgen metabolites or parasite burden did not fully support the physiological and the parasite hypotheses, while the foraging constraint, the energy‐saving and the physical rest hypotheses could not be discounted. Territorial males decreased the time spent lying down from the pre‐rut to the rut, but not their foraging‐to‐lying‐down ratio. During the mating period, we found negative correlations between time spent foraging or lying down and time spent rutting. Our data suggest that territorial males’ behaviour is more consistent with the foraging constraint hypothesis than with the energy‐saving hypothesis previously suggested. Yet, during the rut territorial males did not maximise their foraging time, and the optimisation of their energy balance could rather depend upon feeding on relatively high‐quality plants. This suggestion – possibly named ‘forage quality hypothesis’ – now requires further investigations. This work showed that alternative mating behaviours may underlie different patterns of foraging strategies: we suggest that tests of alternative hypotheses to explain rut‐induced hypophagia within ungulate populations should not ignore the occurrence of AMTs.     

The reproductive pattern of male dusky salamanders (genus Desmognathus) is neither associated nor dissociated

Many seasonally breeding vertebrate species have an associated reproductive pattern: mating behavior, gonadal activity, and peak circulating androgen levels occur simultaneously. In these species, androgens influence the expression of male mating behavior. Other species have a dissociated reproductive pattern: mating behavior occurs at a different time than peak gonadal activity. In such species, it is hypothesized that mating behavior is not dependent on androgen levels [Crews, D., 1984. Gamete production, sex hormone secretion, and mating behavior uncoupled. Horm. Behav. 18, 22-28]. The salamander Desmognathus ochrophaeus mates in the spring and fall while spermatogenesis occurs during the summer, suggesting that it has a dissociated reproductive pattern and that androgens do not mediate mating behavior. To assess whether mating behavior is regulated by gonadal androgens, we castrated males to reduce endogenous androgens and implanted testosterone propionate (TP) to restore androgen levels. Castrated males mated significantly less than did control males. Castrated males given TP mated as much as control males. Compared to controls, circulating androgen levels (both testosterone (T) and dihydrotestosterone (DHT)) were reduced in castrated males and elevated in castrated males given TP implants. We also found that plasma corticosterone (CORT) levels were strongly and positively correlated with T levels. Together, these data indicate that, although spermatogenesis is dissociated in time from mating behavior, androgens are associated with the expression of mating. Thus, the associated-dissociated dichotomy does not adequately describe the reproductive pattern of D. ochrophaeus. We discuss the limitations of the associated-dissociated framework in clarifying hormone-behavior relationships in reptiles and amphibians.     

Reproductive effort of bison bulls (<Emphasis Type="Italic">Bison bison</Emphasis>) in semi-natural conditions

Reproductive effort (RE) is defined as the investment in any current reproductive act. In male ungulates, variation in RE can be explained by differences in age, dominance, phase in the breeding season and number of oestrus females simultaneously present. We investigated the relation between these factors and RE in American bison males in semi-natural conditions. We looked for differences between males in RE, measured by tending behaviour, and maintenance activities (feeding/resting) during the rut. We found no effect of age on RE. During early rut there was no difference in RE between males of different rank. Dominant males had a higher RE during peak rut, and in late rut both the first and second ranking males showed more RE than lower ranking bulls. For all males, there was a clear increase in RE towards peak rut and when more females were attractive. Maintenance behaviours decreased when more females were synchronously in oestrus. The most dominant bulls spent less time grazing than lower ranking males, and all males decreased feeding during peak rut. Resting decreased with age. We conclude that dominance, phase of rut and the number of females synchronously in oestrus are the factors that best explain variation in RE.     

Longitudinal monitoring of plasma and fecal androgens in the Tasmanian devil (Sarcophilus harrisii) and the spotted-tailed quoll (Dasyurus maculatus)

Improved knowledge of the breeding biology of carnivorous marsupials is warranted given their heightened conservation status. Past studies have focused on smaller dasyurids and little is known of male reproductive physiology in the larger species. This study aimed to characterize the pattern of androgen concentrations in male devils and spotted-tailed quolls and to evaluate fecal steroid measurement as a practical, alternative technique for monitoring reproductive activity. Blood and fecal samples were collected from captive adult devils (n=6) and adult quolls (n=8). Plasma and fecal androgen concentrations were significantly positively correlated. In both species there was a significant effect of season on androgen concentrations; and the annual increase preceded female estrus activity. For devils, fecal androgens were elevated during the austral summer: peak concentrations were observed in January-February, and copulation occurred from late February-late May. In quolls, fecal androgen concentrations were highest during austral autumn/winter: the annual increase began in April and copulation occurred from mid-May to early October. The lengthy period of elevated plasma and fecal androgens and protracted annual period of mating activity implies a period of extended spermatogenesis in both species.     

Seasonal behavioral patterns of captive alpine musk deer (<Emphasis Type="Italic">Moschus sifanicus</Emphasis>): Rut and pre-rut comparisons

Alpine musk deer (Moschus sifanicus), well-known for their musk production, are endemic to western China. Due to historical unrestricted illegal hunting and habitat loss, captive farming has been employed as a means of conserving this endangered species and developing sustainable musk harvesting techniques. For captive animals, an understanding of behavioral characteristics is vital to improve management practices. This study addressed a lack of information regarding the behavioral characteristics of alpine musk deer; specifically daily activity patterns in respect to gender and reproductive season. From August 2002 to January 2003, focal sampling was employed to observe 32 adult captive alpine musk deer (13 females and 19 males), at Xinglongshan Musk Deer Farm (XMDF), located at Xinglongshan National Nature Reserve, Gansu Province, China. Results indicated that the general behavioral patterns were similar between female and male captive alpine musk deer throughout both reproductive and non-reproductive seasons (rut and pre-rut season). Both male and female alpine musk deer demonstrated tail-pasting behavior during rut season, a previously male-only behavior trait. Female musk deer also rested comparatively more than males during pre-rut season.     

Reproductive success of bison bulls (Bison bison bison) in semi-natural conditions

Sexual size dimorphism has been related to a high variance in male reproductive success. Research on American bison (Bison bison bison), a species that shows moderate sexual dimorphism, has put forward the assumption that under wild conditions the largest part of the female herd is bred by a limited number of males. Thus far, this hypothesis has never been supported by genetic data. The aim of this study is therefore to test the hypothesis of extreme male reproductive variance among bison through the determination of the reproductive success of the bulls in private herds. We analysed genetic paternity in four private herds (n=19, 33, 39 and 54) kept under semi-natural conditions. By analysing blood, hair and tissue samples, using 8-10 polymorphic microsatellites, the reproductive success of the bulls was quantified. Additional genetic data were gathered through a survey distributed among bison breeders with private herds over the world. Results show a highly differential reproductive success for bison males in private herds kept under semi-natural conditions. In each study group, a single male sires at least 70% of the calves. In the survey groups, a single male sires 81-100% of the calves. Only one survey group displayed a deviating pattern showing a more evenly distribution of paternity (28.57, 33.33 and 38.10%) among three same aged subadult males.     

Hormones and mating system affect sex and species differences in immune function among vertebrates

Males generally exhibit reduced immune responses as well as increased intensity and prevalence of infections compared to female conspecifics. Physiologically, these sex differences may reflect the immunosuppressive effects of androgens. In addition to suppressing immune function, androgens maintain several characteristics important for reproductive success. Thus, a dynamic relationship is assumed to exist among hormones, secondary sex traits, and the immune system. Ultimately, the extent to which this relationship exists may be related to the mating system. Because polygynous males generally have higher circulating testosterone concentrations and rely more heavily on testosterone-dependent traits for reproductive success than monogamous males, sex differences in immune function are hypothesised to be more pronounced among polygynous as compared to monogamous species. Additionally, if secondary sex traits are used to advertise infection status, then females should be able to use the condition of male secondary sex traits to discern the immune/infection status of males during mate selection. The purpose of this review is to survey current studies that examine both the proximate mechanisms and ultimate function of variation in immune function and susceptibility to infection and determine whether immunological variation influences mate preference and possibly reproductive success.     

Sociality, Mate Choice, and Timing of Mating in American Bison (Bison bison): Effects of Large Males

We studied group size, composition, and mating activities in American bison (Bison bison) during rut on the Delta Junction Bison Range in interior Alaska, USA, in 1996 and 1997. Our purpose was to determine the effects of large males (≥5 yr old) on mating and associated activities. Groups with large males were larger than those containing smaller males. Most groups of bison were mixed‐sex (90%), but large males occurred in only one‐half of all groups. Moreover, females in groups with large males were more likely to copulate than those in groups with smaller males, indicating a female preference for large males. Nevertheless, our results are consistent with large males seeking out adult females for mating rather than vice versa. Mating peaked in mid‐August during both the study years and was highly synchronous. Scent marking was coincident with mating, an outcome consistent with a hypothesis of such behavior triggering ovulation. Scent marking by large male bison occurred in both male–male and male–female contexts, but was associated most often with sexual activities. No differences in group size occurred with changes in weather or among vegetation types occupied by bison. Group size of bison, however, was larger with increasing distance from the forest edge, which likely was a response to predation risk in this predator‐rich environment.     

Maternal androgens in the pied flycatcher: timing of breeding and within-female consistency

Maternal hormones can have substantial phenotypic effects in the progeny of many vertebrates. It has been proposed that mothers adaptively adjust hormone levels experienced by particular young to optimize their reproductive output. In birds, systematic variation in egg hormone levels has been related to different female reproductive strategies. Because in many bird species prospects of the offspring change seasonally and with brood number, strategic adjustment of yolk androgen levels would be expected. To test this idea, we induced pied flycatcher (Ficedula hypoleuca) females to nest twice during the same season by removing their first clutches shortly after clutch completion. We collected eggs of first and replacement clutches to measure yolk concentrations of androstenedione (A4) and testosterone (T) and captured the females that laid these clutches for phenotypic measurements. Although average egg androgen levels were remarkably consistent within females, hormone patterns differed considerably between first and replacement clutches. Eggs of replacement clutches were heavier with larger yolks compared to first clutches, but they contained on average lower levels of androgens. Within clutches, androgen concentration increased over the laying sequence in the first clutch, but decreased or remained more constant over the laying sequence in the replacement clutch. Mean yolk T, but not A4 levels, were negatively associated with laying date for both breeding attempts. Moreover, females in good body condition produced eggs containing lower levels of androgens than females in poor condition. Our results are consistent with the idea that differences in yolk androgen levels may be one mechanism underlying seasonal variation in reproductive success and it is possible that changes in egg androgen patterns may reflect a change in female reproductive strategy. High within-female consistency also highlights the possibility that there may be some underlying genetic variation in yolk androgen levels.     

Group dynamics of the Nubian ibex (Capra ibex nubiana) in the Tuwayiq Canyons, Saudi Arabia

Group dynamics of the Nubian ibex ( Capra ibex nubiana ), a sub-species adapted to arid environments, were studied at the Ibex Reserve, Saudi Arabia. Most of the animals (83%) were seen in mixed herds during the rut and post-rut. Mean group size of all sex-age categories was 7.2, with the majority of the ibex seen in groups of < 10. The sex ratio of adult animals was equal but that of juveniles, older than six months, was skewed towards females. Habitat structure, sparse vegetation cover and a small population size are factors that favour small group size. An equal adult sex ratio and a high number of juveniles indicate that the population has a high reproductive potential.