Parasitism and alternative reproductive tactics in Northern chamois

Alternative reproductive tactics (ARTs), discrete phenotypic variations evolved to maximize fitness, may entail different cost‐benefit trade‐offs. In large mammals, differences in costs associated with ARTs—including energy expenditure and parasite infection—are typically greatest during the breeding season. Nonetheless, physiological and behavioral differences between ARTs can manifest throughout the year, possibly involving costs that may contribute to maintain ARTs within populations. Using the number of nematode larvae per gram of feces (LPG) as a proxy, we explored the temporal changes in lung parasite infection in territorial and nonterritorial male chamois Rupicapra in the Gran Paradiso National Park (Italy), between 2011 and 2012. We aimed to identify which tactic‐specific physiological and behavioral features (including age, hormonal levels, inter‐ and intrasexual interactions, and space use) or climatic factors (temperature and precipitation) best explained yearly variation in parasite infection within and between ARTs. Generalized additive mixed models showed that the fecal larval counts of lung nematodes underwent strong temporal changes in both male types. Differences between ARTs (with higher LPG values in territorial than nonterritorial males) were greatest during the rut and—to a lesser extent—in spring, respectively, at the peak and at the onset of territoriality. The difference in LPG between tactics was largely explained by the greater levels of hormone metabolites in territorial males during the rut. The other variables did not contribute significantly to explain the different shedding of larvae within and between ARTs. Our analysis suggests that different values of LPG between territorial and nonterritorial males are largely a result of tactic‐specific differences in the secretion of hormone metabolites, but only during the rut. To clarify whether rut‐related parasitism contributes to the maintenance of ARTs, tactic‐specific life history trade‐offs, for example, between reproduction and parasite‐related mortality, must be investigated.     

Age-specific survival of territorial and non-territorial male chamois

How alternative reproductive tactics (ARTs) are maintained in wildlife populations is one of the major questions in evolutionary biology. As a dominant status, territoriality is typically linked to increased mating opportunities, and one explanation why this behaviour coexists with other tactics is that dominance implies survival costs. Such a trade-off may occur in the Northern chamois Rupicapra rupicapra, as reproductive advantages of territorial males over non-territorial males could be counterbalanced by a reduction in survival mediated through energy expenditure, stress and parasitic infections, ultimately favouring ART coexistence. Here, we analysed age-dependent survival probabilities of territorial (n = 15) and non-territorial (n = 16) adult chamois using information collected over 12 years between 2010 and 2021 in the Gran Paradiso National Park (Western Italian Alps). Survival rates were estimated with a CMR approach using Burnham's joint modelling of live encounter and dead recovery data. The model selection procedure, based on AICc value minimisation, supported a linear decrease of survival with age but the results did not match our predictions, as territorial chamois did not have lower survival rates than non-territorial chamois. In contrast, territorial males appeared to enjoy reproductive success at lower survival costs. This, in turn, supports the role of other factors, such as snow-dependent environmental stochasticity, in the maintenance of ARTs in chamois populations. The limited sample size, however, calls for caution in interpretation, and long-term studies of lifetime reproductive success and survival are necessary to clarify the mechanisms underlying the expression and coexistence of different reproductive behaviours in this species.     

Manipulations of the AVT system shift social status and related courtship and aggressive behavior in the bluehead wrasse

Arginine vasotocin (AVT) and its mammalian homologoue arginine vasopressin (AVP) influence male sexual and aggressive behaviors in many species. We tested the effects of AVT and an AVP-V(1a) receptor antagonist on the display of alternative male tactics in a tropical coral reef fish, the bluehead wrasse Thalassoma bifasciatum. We gave AVT injections to territorial and nonterritorial males of the large and colorful phenotype (terminal phase) and an AVP-V(1a) receptor antagonist, Manning compound, to territorial males in the field. AVT increased courtship independent of status, while its effects on territoriality and aggression were dependent upon male status. In territorial males, AVT increased courtship and tended to decrease the number of chases toward initial phase individuals. In nonterritorial males, AVT increased courtship, chases toward initial phase individuals, and territorial behavior while decreasing feeding. These are all behaviors rarely seen in nonterritorial males, so AVT made these males act like territorial TP males. The AVP-V(1a) receptor antagonist had opposite effects. It decreased courtship and territorial defense, making these males act more like nonterritorial males. Manipulations of the AVT system shifted males within a single phenotype from the nonterritorial social status to the territorial social status and vice versa. Since the entire suite of behaviors related to territoriality was affected by AVT system manipulations, our results suggest that the AVT system may play a key role in motivation of behaviors related to mating.     

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.     

Feeding or Resting? The Strategy of Rutting Male Alpine Chamois

Optimal foraging theory suggests that animals normally maximize energy intake to optimize their energy balance. However, when efficiency to assimilate energy falls below the level necessary to ascertain basal energetic requirements, they should shift to an energy saving strategy. Males of many ruminant species considerably reduce their food intake during the rut. Nevertheless, they are commonly assumed to maximize energy intake besides their investments in rutting activities. Based on predictions of optimal foraging theory and the specific ruminant digestive physiology, we propose, however, that rutting males in polygynous species with time consuming mating tactics should instead use an energy saving strategy. Particularly, we predict this to be the case in Alpine chamois (Rupicapra rupicapra rupicapra), a highly polygynous mountain ungulate, of which the males defend mating territories during the rut. By combining observational and telemetry data of eight radio‐collared males we constructed individual 24‐h time budgets, and compared the behavior of males before, during and after the rut. Males spent significantly less time feeding during the rut (0.9 h) compared with before (8.5 h) and afterwards (6.4 and 7.5 h, respectively), whereas time spent lying remained more or less unchanged (pre‐rut; 12.7 h, rut; 13.3 h, post‐rut; 12.9 and 13.9 h, respectively). The ratio of time spent feeding to lying dropped from 0.67 in the pre‐rut period to 0.05 in the rutting period. As a result, males allocated on average approx. 90% of their non‐rutting time to lying, and a negative relationship between rutting and lying time emerged. Hence, males seemed to trade lying time against rutting time. We conclude from these results that male Alpine chamois do not maximize their energy intake during the rut, but rather adopt an energy saving strategy to optimize their energy balance.     

Environmental and endocrine correlates of tactic switching by nonterritorial male tree lizards (Urosaurus ornatus)

Animals often exhibit individual variation in their behavioral responses to the same stimuli in the biotic or abiotic environment. To elucidate the endocrine mechanisms mediating such behavioral variation, we have been studying a species of lizard with two distinct male phenotypes. Here we document behavioral variation across years in one of the two male phenotypes of the tree lizard, Urosaurus ornatus, and present hormone data that support an endocrine mechanism underlying this behavioral variation. Nonterritorial male tree lizards appear to be nomadic rovers in some years and sedentary satellites in others, whereas territorial males are always territorial. This behavioral variation by nonterritorial males was correlated with environmental conditions. In environmentally harsher years (as assessed by rainfall), nonterritorial males appear to behave as nomads, whereas in more benign years they are more site-faithful. A between-year comparison of levels of corticosterone and testosterone for the two male phenotypes supports a model for how hormones underlie the males' reproductive tactics, particularly the nonterritorial males' behavioral plasticity. In an environmentally harsher (drier) year, both types of males had higher corticosterone levels than in a milder (wetter) year, but only nonterritorial males had lower testosterone in the relatively harsher year. We propose that disruptive selection for individual variation in hormonal responses to environmental cues may be a common mechanism underlying the evolution of alternative male reproductive tactics in this and other species.     

Do individuals in better condition survive for longer? Field survival estimates according to male alternative reproductive tactics and sex

There is a gap in terms of the supposed survival differences recorded in the field according to individual condition. This is partly due to our inability to assess survival in the wild. Here we applied modern statistical techniques to field‐gathered data in two damselfly species whose males practice alternative reproductive tactics (ARTs) and whose indicators of condition in both sexes are known. In Paraphlebia zoe, there are two ART: a larger black‐winged (BW) male which defends mating territories and a smaller hyaline‐winged (HW) male that usually acts as a satellite. In this species, condition in both morphs is correlated with body size. In Calopteryx haemorrhoidalis, males follow tactics according to their condition with males in better condition practicing a territorial ART. In addition, in this species, condition correlates positively with wing pigmentation in both sexes. Our prediction for both species was that males practicing the territorial tactic will survive less longer than males using a nonterritorial tactic, and larger or more pigmented animals will survive for longer. In P. zoe, BW males survived less than females but did not differ from HW males, and not necessarily larger individuals survived for longer. In fact, size affected survival but only when group identity was analysed, showing a positive relationship in females and a slightly negative relationship in both male morphs. For C. haemorrhoidalis, survival was larger for more pigmented males and females, but size was not a good survival predictor. Our results partially confirm assumptions based on the maintenance of ARTs. Our results also indicate that female pigmentation, correlates with a fitness component – survival – as proposed by recent sexual selection ideas applied to females.     

Allometry of a sexual trait in relation to diet experience and alternative mating tactics in two rubyspot damselflies (Calopterygidae: Hetaerina)

Several arguments have been put forward to explain how sexual selection drives the evolution of sexual trait allometry, especially hyperallometry. The ‘positive allometry theory’ suggests that hyperallometry is a rule in all‐secondary sexual traits, whereas the ‘display hypothesis’ suggests that only males in good condition will exhibit hyperallometric sexual display traits. In the present study, we investigated: (1) the condition‐dependence nature (by using two diet treatments that varied in the amount of food provided to the larvae) of a sexually selected trait (wing pigmentation; WP) in recently‐emerged adults of the American rubyspot damselfly, Hetaerina americana, and (2) the scaling relationship between WP and body size (wing and body length) in the rubyspot damselflies H. americana and Hetaerina vulnerata, according to alternative reproductive tactics (ARTs; territorial and nonterritorial males). First, we found support that indicated that diet positively affected WP length, although there was no significant WP allometric pattern in relation to diet regimes. Second, WP was hyperallometric in both Hetaerina species. WP size was similar between ARTs and, in H. americana (but not H. vulnerata), nonterritorial males showed steeper slopes than territorial males when wing length was used. The results obtained support the notion that sexual traits are hyperallometric, although there is no clear pattern in relation to ARTs. © 2013 The Linnean Society of London     

Alternative reproductive tactics and the propensity of hybridization

One explanation for hybridization between species is the fitness benefits it occasionally confers to the hybridizing individuals. This explanation is possible in species that have evolved alternative male reproductive tactics: individuals with inferior tactics might be more prone to hybridization provided it increases their reproductive success and fitness. Here we experimentally tested whether the propensity of hybridization in the wild depends on male reproductive tactic in Calopteryx splendens damselflies. Counter to our expectation, it was males adopting the superior reproductive tactic (territoriality) that had greatest propensity to hybridize than males adopting the inferior tactics (sneakers and floaters). Moreover, among the territorial males, the most ornamented males had greatest propensity to hybridize whereas the pattern was reversed in the sneaker males. Our results suggest that there is fluctuating selection on male mate discrimination against heterospecific females depending on both ornament size and the male’s reproductive tactic.     

Relative fitness of alternative male reproductive tactics in a mammal varies between years

1. In many species, males can use different behavioural tactics to achieve fertilization, so-called alternative reproductive tactics (ARTs). Few field studies have measured fitness consequences of ARTs under varying environmental conditions. 2. Here, we describe fitness consequences of three phenotypically plastic ARTs in the African striped mouse (Rhabdomys pumilio) and show that relative fitness of ARTs differs between years. Each year represents a different generation. 3. For the generation living under high population density, tactics differed in relative fitness in accordance with the theory of conditional strategies, with highly successful territorial breeding males having 10 times higher success than solitary roaming males and 102 times higher success than adult natally philopatric males. 4. For the generation living under intermediate population density, the territorial breeding and roaming tactics yielded similar fitness, which would be in agreement with the theory of mixed strategies. No philopatric males occurred. 5. For the generation living under low population density, roaming was the only tactic used and some roamers had very high fitness. 6. The main prediction of status-dependent selection for conditional strategies is a correlation between fitness and status, often measured as body mass, but we did not find this correlation within tactics when more than one tactic was expressed in the population. 7. Female distribution seems to have an effect on which reproductive tactics male chose: female defence polygyny when females are clumped (interference competition), but a searching tactic when females are dispersed (scramble competition). In contrast to predictions arising from theory on scramble competition, male body mass was important in determining fitness only in the year when females were dispersed, but not in other years. 8. Our results indicate that the differentiation between conditional and mixed strategies is not an absolute one. In many other species, environmental conditions might fluctuate temporally and spatially so that the normally suboptimal tactic yields similar fitness to the (usually) dominant tactic or that only a single tactic prevails. 9. We suggest the term single strategy, independent of current fitness consequences, for systems where tactics are not genetically determined, in contrast to genetically determined alternative strategies.     

Preliminary analysis of reproductive success in a large mammal with alternative mating tactics,the Northern chamois,Rupicapra rupicapra

In polygynous mating systems, reproductive skew depends on the ability of males to monopolize females, which in turn may promote the development of contrasting traits in the two sexes. Although dominant individuals normally enjoy a higher reproductive success (RS) than subordinates, the use of genetic markers has shown that behavioural observations of male mating success may not provide reliable clues of RS. We report the preliminary results of the first DNA‐based paternity analysis on the Northern chamois (Rupicapra rupicapra), a scarcely dimorphic mountain ungulate described as highly polygynous, in relation to mating tactic and age. Because of sampling difficulties, the success in parentage assignment was low, and the interpretation of results requires caution. Territorial males had a greater RS than nonterritorial ones but they were unable to monopolize mating events. Age had a weak effect on paternity outcome but only males ≥ 6 years showed siring success. Although future studies are needed to assess the opportunity for sexual selection in male chamois, the concurrence of limited sexual size dimorphism, compensatory growth, unbiased sex‐specific survival, RS of alternative mating tactics and, possibly, long breeding tenure, may hint at the adoption of a conservative mating strategy in this species.     

Male Alpine Chamois Occupy Territories at Hotspots Before the Mating Season

Ungulate mating systems vary broadly both between and within species. Studies on mating systems in different habitats can provide clues to the ecological factors determining this diversity. Despite its abundance in the European Alps and its importance as a game species, surprisingly little is known about the mating system of Alpine chamois Rupicapra rupicapra rupicapra. We tested the hypothesis that adult males first defend mating territories in late spring, when females segregate from males and well before the Nov. rut. In the Gran Paradiso National Park (north‐western Italian Alps), adult males shared a winter range but occupied individual ranges in summer and early autumn. Males were more aggressive to each other in the summer than in the spring. A strong site fidelity from one year to the next was found for the summer and early autumn months. Those males that occupied the same territories both in the summer and during the rut (Nov.) appeared to be at hotspots, attractive to females during the rut because of reduced snow cover. Other males appeared to cluster around these hotspots during the rut. Territories that were first occupied during the summer were visited by more females than those that were not established until the rut began. Our results suggest that the mating system of this population of Alpine chamois consists of the early occupation of clustered mating territories. The early establishment of mating territories in areas frequented by females during the rut may lead to reproductive benefits for male chamois.     

Antagonistic selection on body size and sword length in a wild population of the swordtail fish,Xiphophorus multilineatus: Potential for intralocus tactical conflict

Alternative reproductive tactics (ARTs) have provided valuable insights into how sexual selection and life history trade‐offs can lead to variation within a sex. However, the possibility that tactics may constrain evolution through intralocus tactical conflict (IATC) is rarely considered. In addition, when IATC has been considered, the focus has often been on the genetic correlations between the ARTs, while evidence that the ARTs have different optima for associated traits and that at least one of the tactics is not at its optimum is often missing. Here, we investigate selection on three traits associated with the ARTs in the swordtail fish Xiphophorus multilineatus; body size, body shape, and the sexually selected trait for which these fishes were named, sword length (elongation of the caudal fin). All three traits are tactically dimorphic, with courter males being larger, deeper bodied and having longer swords, and the sneaker males being smaller, more fusiform and having shorter swords. Using measures of reproductive success in a wild population we calculated selection differentials, as well as linear and quadratic gradients. We demonstrated that the tactics have different optima and at least one of the tactics is not at its optimum for body size and sword length. Our results provide the first evidence of selection in the wild on the sword, an iconic trait for sexual selection. In addition, given the high probability that these traits are genetically correlated to some extent between the two tactics, our study suggests that IATC is constraining both body size and the sword from reaching their phenotypic optima. We discuss the importance of considering the role of IATC in the evolution of tactical dimorphism, how this conflict can be present despite tactical dimorphism, and how it is important to consider this conflict when explaining not only variation within a species but differences across species as well.     

Do Feeding Resources Induce the Adoption of Resource Defence Polygyny in a Lekking Butterfly?

Among polygynous species, males often compete for the possession of mating sites to increase their reproductive success. Weaker individuals frequently adopt alternative non‐territorial mate‐locating tactics, but the adoption of alternative territorial tactics may also occur. Although alternative tactics with territory defence are less common in arthropods, factors that drive its adoption may provide information to understand the organization of different territorial mating systems in the group. Here we investigate the adoption of resource‐based territoriality as an alternative to a non‐resource‐based one by males of the butterfly Paryphthimoides phronius. Male P. phronius commonly defend sunny clearings lacking feeding resources in the forest edge (non‐resource‐based territoriality). However, after experimentally offering fermenting fruit in previously undefended sites, we showed that males also adopt a resource defence tactic. Males in territories with fermenting fruits apparently feed on this resource when they are not defending the territory. However, males in sites without resources did not migrate to territories with resources when given the opportunity. To our knowledge, this is the first experimental investigation to show a non‐resource‐ and an alternative resource‐based mate‐locating tactic in a butterfly. We suggest that this behavioural flexibility may represent an important step to understand the ecological factors responsible for the organization and evolution of different territorial mating systems in insects.     

Determinants and long‐term costs of early reproduction in males of a long‐lived polygynous mammal

In long‐lived polygynous species, male reproductive success is often monopolized by a few mature dominant individuals. Young males are generally too small to be dominant and may employ alternative tactics; however, little is known about the determinants of reproductive success for young males. Understanding the causes and consequences of variability in early reproductive success may be crucial to assess the strength of sexual selection and possible long‐term trade‐offs among life‐history traits. Selective pressures driven by fluctuating environmental conditions may depend on age class. We evaluated the determinants of reproduction in male bighorn sheep (Ovis canadensis) aged 2–4 years using 30 years of individual‐level data. These young males cannot defend estrous ewes and use alternative mating tactics. We also investigated how the age of first detected reproduction was correlated to lifetime reproductive success and longevity. We found that reproductive success of males aged 3 years was positively correlated to body mass, to the proportion of males aged 2–4 years in the competitor pool, and to the number of females available per adult male. These results suggest that reproductive success depends on both competitive ability and population age–sex structure. None of these variables, however, had significant effects on the reproductive success of males aged 2 or 4 years. Known reproduction before the age of five increased lifetime reproductive success but decreased longevity, suggesting a long‐term survival cost of early reproduction. Our analyses reveal that both individual‐level phenotypic and population‐level demographic variables influence reproductive success by young males and provide a rare assessment of fitness trade‐offs in wild polygynous males.     

Correlates of Territoriality in Rutting Red Deer

The mating strategy most commonly reported for male red deer, Cervus elaphus, is the defence of females (harems), territoriality having been described only in Doñana, Spain. We observed rutting males at five different populations in Spain and during 4 consecutive yr in Doñana. Female defence was the only strategy observed in two of the populations, whereas territorial defence coexisted with female defence in the remaining three populations. Territorial defence appeared to be more costly than female defence, in terms of rates of aggressive interaction, and territorial males tended to gather more females per d than non-territorial ones. Both mating strategies seemed to respond to local variations in habitat, which in turn affected female distribution. Females concentrated in areas with high-quality forage, and most territories contained patches of high-quality food (i.e. greater quality within boundaries) or were located along main routes used by females. The results are interpreted in the light of environmental conditions in southern Europe, where the rut coincides with the less favourable season for herbivores (in terms of food resources) after the hot and dry summer. Under such conditions of food scarcity coupled with patchy distribution, females tend to concentrate on the remaining patches of green swards, and males benefit from defending the food resources that attract females.     

Ammotragus free-ranging population in the south-east of Spain: a necessary first account

This is the first attempt to investigate some characteristics of a Spanish population of Ammotragus lervia introduced in the wild back in 1970. Apart from a short account of the population history and proceeding up to the present, a comparison between population data reported for the American wild populations and the Spanish one is provided. The surveys were conducted during breeding and rutting seasons. The majority of the herds sighted in Sierra Espuña were made up of 1–10 individuals, and adult males were more frequently observed during rutting. The group composition more commonly observed during breeding is that of adult females and subadults, i.e., nursery herds. A different habitat use was obtained depending on the season and sex-age class. These results are consistent with the dynamics of ungulates and their reproductive phenology. Suggestions for future research and conservation-management concerns in the area are provided.     

Does a temperate ungulate that breeds in summer exhibit rut-induced hypophagia? Analysis of time budgets of male takin (Budorcas taxicolor) in Sichuan,China

Mammals maximize fitness by optimizing time and energy allocation between reproduction and survival. Describing time budgets is a way to understand a species' constraints in energy allocation. We describe a time budget for male takin (Budorcas taxicolor) in Tangjiahe Nature Reserve, China, to better understand rut-induced hypophagia, which is frequently observed in temperate ungulates that breed in autumn or in winter. Observations generally occurred at two elevations (1200-1600m and 2600-3200m), using 20-min focal animal scan sampling from 2007 to 2009. Feeding behaviors accounted for the majority in takin's time budget (61.1%) during daylight hours, relative to the other observed behaviors, such as rest (14.1%), alert behavior (10.2%) and locomotion (6.8%). We found a negative correlation between feeding behavior and rutting behavior during the rutting season. A ratio of feeding time to resting time increased from pre-rut to rut, while resting behavior did not change significantly across seasons. These results suggest the "energy saving" hypothesis could explain reduced foraging in male takin during the rut, but aspects of the species biology suggest that hypotheses for rut-induced hypophagia developed for other temperate ungulates do not apply to takin. We suggest that the unusual summer rutting season of takin releases males from the energy constraints encountered by temperate ungulates that breed in the autumn and has other benefits for offspring survival. Further research should be conducted on ungulates that exhibit rut during the summer and tropical ungulates that might not experience limited food availability following the mating season to improve our understanding on rut-induced hypophagia.     

Rut-Induced Hypophagia in Male Bighorn Sheep and Mountain Goats: Foraging Under Time Budget Constraints

In polygynous ungulates, the rut imposes constraints on male time budgets that generate a trade‐off between maintenance and reproduction, leading to a reduction in time spent foraging. As mating activities can incur substantial somatic costs, males are expected to spend their ‘non‐rutting’ time recovering during the breeding season. If the diminution in time allocated to foraging by males is only a consequence of time budget constraints, males should keep a similar ratio of time spent foraging to lying to that observed in the pre‐rut, leading to an overall reduction of these two activities (the ‘foraging constraint’ hypothesis). Alternatively, if males adopt an energy‐saving strategy, they should limit energy expenditures by reducing foraging but not lying time, as the energy gains of forage intake may not meet the basal energetic requirements, especially in northern and temperate regions (the ‘energy‐saving’ hypothesis). Here, we contrast these two hypotheses by comparing individual daily time budgets of marked adult bighorn sheep rams (Ovis canadensis) and male mountain goats (Oreamnos americanus) during the pre‐rut and the rut. Concordant results for both species support the ‘foraging constraint’ hypothesis, as sexually‐active males reduced time spent foraging and lying from the pre‐rut to the rut because of an increase in time spent in mating‐related activities. Bighorn sheep rams also increased time spent foraging when not engaged in mating tactics, providing further support for a ‘maximisation’ of energy intake in the absence of reproductive opportunities. Because there are also known physiological changes that occur during the rut which may cause appetite suppression, for example to produce metabolic compounds linked with olfactory communication (the ‘scent‐urination’ hypothesis) or to cope with increased burden of parasites (the ‘parasite‐induced anorexia’ hypothesis), further research should aim at simultaneously testing these current hypotheses to better understand rut‐induced hypophagia and its effects on the life histories of male ungulates.     

Habitat and climate shape growth patterns in a mountain ungulate

Uptake and use of energy are of key importance for animals living in temperate environments that undergo strong seasonal changes in forage quality and quantity. In ungulates, energy intake strongly affects body mass gain, an important component of individual fitness. Energy allocation among life‐history traits can be affected by internal and external factors. Here, we investigate large‐scale variation in body growth patterns of Alpine chamois Rupicapra rupicapra rupicapra, in relation to sex, age, temperature, and habitat variations across 31 (sub)populations in the Central European Alps. Taking advantage of an exceptionally large dataset (n = 178,175) of chamois hunted over 27 consecutive years between 1993 and 2019 in mountain ranges with different proportions of forest cover, we found that (i) patterns of body mass growth differ between mountain ranges, with lower body mass but faster mass growth with increasing proportion of forest cover and that (ii) the effect of spring and summer temperatures on changes in body growth patterns are larger in mountain ranges with lower forest cover compared to mountain ranges with higher forest cover. Our results show that patterns of body mass growth within a species are more plastic than expected and depend on environmental and climatic conditions. The recent decline in body mass observed in Alpine chamois populations may have greater impacts on populations living above the treeline than in forests, which may buffer against the effects of increasing temperatures on life‐history traits.