Resident Males Research Articles

Does kinship affect spatial organization in a small and isolated population of a solitary felid: The Eurasian lynx?

Social organization in wild carnivores is mostly determined by patterns of family bonds, which may shape the degree of relatedness among individuals in the population. We studied kinship in a small and isolated population of a solitary carnivore, the Eurasian lynx (Lynx lynx) to evaluate its effect on spatial distribution of individuals. We investigated the relationship between spatial location and pair-wise kinship among 28 lynx individuals identified in 2004-2011 by telemetry, non-invasive sampling and genotyping with the use of 12 autosomal microsatellites in the Białowieża Primeval Forest, Poland. The average relatedness of the lynx population was relatively low (Lynch and Ritland's R = 0.03). Females were significantly more related to each other than males with other males. The inferred pedigree showed that the population was dominated by only 2 familial groups. We did not find significant correlations between the relatedness and the extent of home range overlap or the straight-line distances between the home ranges' central points. These results suggest that the dynamics of kinship in this solitary felid may not differ from the random mating processes described in social carnivores. Although the chances of random mating could be limited to a few resident males and females, the presence of unrelated floaters may provide a "breeding buffer" that may prevent an increase of relatedness and likely inbreeding in the population. This system is likely to fail in preserving genetic diversity in small, highly isolated populations; therefore, restoring habitat connectivity is crucial to ensure sufficient immigration from neighboring populations.

Grandparentage assignments identify unexpected adfluvial life history tactic contributing offspring to a reintroduced population.

Diversity in life history tactics contributes to the persistence of a population because it helps to protect against stochastic environments by varying individuals in space and time. However, some life history tactics may not be accounted for when assessing the demographic viability of a population. One important factor in demographic viability assessments is cohort replacement rate (CRR), which is defined as the number of future adults produced by an adult. We assessed if precocial resident males (<age‐3) and adfluvial Chinook salmon (Oncorhynchus tshawytscha), adults that reside in freshwater their entire lives, contributed offspring to a reintroduced population from 2008 to 2013. We found that 9 ± 5% of offspring with an unassigned parent remained unexplained after accounting for sources of human error. Using grandparentage assignments, we identified 31 precocial resident males and 48 probable adfluvial Chinook salmon produced by anadromous mate pairs from 2007 to 2012. Previously published CRR estimates for the 2007 and 2008 reintroduced adults, based on only anadromous returning adult offspring, were 0.40 and 0.31, respectively. By incorporating adfluvial females, we found CRR estimates increased by 17% (CRR: 0.46) and 13% (CRR: 0.35) for the 2007 and 2008 cohorts, respectively.

Blood thicker than water: kinship, disease prevalence and group size drive divergent patterns of infection risk in a social mammal.

The importance of social- and kin-structuring of populations for the transmission of wildlife disease is widely assumed but poorly described. Social structure can help dilute risks of transmission for group members, and is relatively easy to measure, but kin-association represents a further level of population sub-structure that is harder to measure, particularly when association behaviours happen underground. Here, using epidemiological and molecular genetic data from a wild, high-density population of the European badger (Meles meles), we quantify the risks of infection with Mycobacterium bovis (the causative agent of tuberculosis) in cubs. The risk declines with increasing size of its social group, but this net dilution effect conceals divergent patterns of infection risk. Cubs only enjoy reduced risk when social groups have a higher proportion of test-negative individuals. Cubs suffer higher infection risk in social groups containing resident infectious adults, and these risks are exaggerated when cubs and infectious adults are closely related. We further identify key differences in infection risk associated with resident infectious males and females. We link our results to parent–offspring interactions and other kin-biased association, but also consider the possibility that susceptibility to infection is heritable. These patterns of infection risk help to explain the observation of a herd immunity effect in badgers following low-intensity vaccination campaigns. They also reveal kinship and kin-association to be important, and often hidden, drivers of disease transmission in social mammals.

Nocturnal songs in a diurnal passerine: attracting mates or repelling intruders?

We addressed the role of nocturnal singing in the diurnal field sparrow, Spizella pusilla. We were particularly interested in whether nocturnal song is used to repel intruders (intrasexual function) and/or to attract females seeking extrapair copulations (intersexual function). First, we used autonomous acoustic recording units (ARUs) and an automated detection and classification system to examine the associations of singing behaviour of mated field sparrows with social factors (fertility stage, presence of neighbour song and presence of intruder song). Second, using an automated radiotelemetry system (ARTS), autonomous acoustic recording units (ARUs) and automated playback systems, we conducted a nocturnal playback experiment to explore how mated male and female field sparrows respond to nocturnal songs at night and across prefertile, fertile and postfertile stages. We found that neighbours and intruder males tended to sing complex songs on the same nights when focal males sang. While not all focal males sang at night, all male birds (resident males, neighbours and intruders) that sang tended to sing according to the fertility periods of the resident male's female. Our playback experiment demonstrated that, although field sparrows usually slept and were inactive at night, they moved in response to nocturnal field sparrow songs more than to control stimuli (other species vocalizations). Interestingly, we found that males did not respond by singing or countersinging to field sparrow nocturnal songs (simulated intrusions). We also demonstrated that male activity responses were similar during the prefertile and postfertile stages, while females responded more during the prefertile and fertile stages than during the postfertile stage. Consequently, the nocturnal song in the field sparrow appears to play a role in extrapair mate attraction (intersexual function) more than in repelling intruders (intrasexual function). While nocturnal singing is an infrequent behaviour of most diurnal birds, it may be important in the mating system of these birds.

Genetic Isolation of Hypothalamic Neurons that Regulate Context-Specific Male Social Behavior.

Nearly all animals engage in a complex assortment of social behaviors that are essential for the survival of the species. In mammals, these behaviors are regulated by sub-nuclei within the hypothalamus, but the specific cell types within these nuclei responsible for coordinating behavior in distinct contexts are only beginning to be resolved. Here, we identify a population of neurons in the ventral premammillary nucleus of the hypothalamus (PMV) that are strongly activated in male intruder mice in response to a larger resident male but that are not responsive to females. Using a combination of molecular and genetic approaches, we demonstrate that these PMV neurons regulate intruder-specific male social behavior and social novelty recognition in a manner dependent on synaptic release of the excitatory neurotransmitter glutamate. These data provide direct evidence for a unique population of neurons that regulate social behaviors in specific contexts.

Aiming low: A resident male's rank predicts takeover success by challenging males in Yunnan snub-nosed monkeys.

In many primate species that form one-male breeding units (OMUs), the threat of a takeover by a bachelor male represents a major challenge to group stability and individual reproductive success. In the case of snub-nosed monkeys, which live in large multilevel or modular societies (MLS) comprising several OMUs that travel, feed and rest together and as well as one or more all male units (AMUs), the process by which rival males challenge resident OMU males for access to females is poorly understood. From September 2012 to October 2013, we recorded 48 cases in which rival males visited an OMU in a MLS of Yunnan snub-nosed monkeys (Rhinopithecus bieti) inhabiting the Baimaxueshan National Nature Reserve, Yunnan Province, China. In 40 cases, rival males engaged in mild agonistic interactions (approaching, staring, teeth-baring and chasing) but failed to take over the group; we counted these visits as failed takeovers, recognizing that they may nevertheless allow rival males to assess the competitive ability of residents. During eight successful takeovers, however, there was severe physical aggression between challenging and resident males, with serious injuries to participants. We found that neither the number of adult and subadult females in an OMU, the number of non-pregnant, non-lactating adult females in an OMU, nor the rank of a resident male relative to other resident males in the MLS predicted which OMU a challenging male targeted for takeover. However, a resident male's rank significantly predicted whether takeover attempts were successful. Specifically, challenging males were more successful in displacing a lower-ranking resident male than a higher-ranking male. Given that a Yunnan snub-nosed monkey MLS may contain as many as 40 resident and 36 bachelor males, continued research is required to determine the set of factors that enable resident males to maintain high social rank and successfully defend their harems. Am. J. Primatol. 78:974-982, 2016. © 2016 Wiley Periodicals, Inc.

Evaluating the responses of a territorial solitary carnivore to potential mates and competitors.

Successful communication is critical to the fitness of individuals and maintenance of populations, but less is known regarding the social contexts and reactions to scent marking by other individuals in solitary carnivores, including pumas. We evaluated the responses of resident male pumas to visitation and scent marking by potential competitors (other male pumas) and potential mates (female pumas) by capturing and marking 46 pumas (Puma concolor), and documenting scent marking behaviours using motion-triggered video cameras. By comparing resident male puma visitation rates and communication behaviours in response to either male or female visitors, we found that their visitation and communication behaviours were best explained by the combination of visitation by both competitors and potential mates. Resident males returned to scent marking sites more quickly and increased their rate of flehmen response after visitation by a females, while they increased their rate of visitation and duration of visits in response to other males. Male pumas also visited less frequently in summer and autumn when female visitation rates were lower, but males created nearly twice as many scrapes during these visits. This study suggests that advertising for mates when scent marking may sometimes overshadow the importance of deterring competitors and claiming territory.

Risk of inbreeding: problem of mate choice and fitness effects?

Mating with close kin may cause inbreeding depression with negative consequences to offspring and local populations. There exist mechanisms like kin-recognition or sex-specific dispersal to avoid mating with kin. In fluctuating population densities, like in many small mammals, both very low and very high densities provide conditions for inbreeding, if kin males are prone to stay in their natal area. Females are choosy and male dominance is thought to be the key feature when selecting mating partners. The aim of this study was to test the possible discrepancy in mate choice and negative fitness effects of inbreeding in two experiments, one in the laboratory and one in field enclosures. We asked (1) how the quality of the potential mating partners affects female choice regardless of relatedness and (2) how inbreeding affects the field populations created either from inbred or outbred individuals. Our results show that primiparous females in post-partum oestrus mated preferably with a dominant male, measured with their urine-marking behaviour, regardless if the selected male was brother or not. Only if the two males offered were of same dominance rank, the female mated with the non-kin male. However, the field experiment verified a negative effect of inbreeding in the bank vole. Thus, there seems to be a mismatch between female mate choice when selecting for dominance among resident males and population viability through long-term inbreeding depression. The study suggests the high importance of sex-biased dispersal as a mechanism to avoid kin individuals to meet in mate choice situations.

A small number of anadromous females drive reproduction in a brown trout (Salmo trutta) population in an English chalk stream

SummaryBrown trout,Salmo trutta, exhibit one of the most highly variable and polytypic life‐history strategies of all salmonids. Populations may be wholly freshwater‐resident or almost exclusively migratory (anadromous), or fish of a single population may exhibit varying proportions of the two life‐history strategies. Both anadromous and freshwater‐resident trout freely interbreed to produce fertile offspring.We quantify maternal reproductive provisioning by anadromous and freshwater‐resident brown trout to their offspring and assess relative parental fitness (in terms of number, size and time of emergence of offspring). Newly emerged juvenile trout (fry) were sampled (n = 119) over the emergence period in March–April 2007 in a lowland English chalk stream; samples of adult trout [anadromous (6F : 12M) and freshwater‐resident (22F : 56M)], river‐resident trout parr and macroinvertebrate prey were also collected.Using a novel combination of stable isotope analysis and microsatellite genotyping we demonstrate the overwhelming contribution of anadromous parents (both female and male) to fry production, despite the obvious presence and numerical dominance of resident adults. We unambiguously identify the maternal origins of 78% of juveniles sampled and show that maternal reproductive contribution to juvenile production in the river was higher for anadromous females (76%) than freshwater‐resident fish (2.5%). Offspring of anadromous females emerged earlier and at a larger body size than offspring of resident females. Similarly, while the relative contribution of resident males (37%) was higher than that of resident females, anadromous males sired considerably more offspring (63%) than resident males. This is the first study of its kind to accurately assess the reproductive contribution of anadromous male trout.Overall, this study suggests that anadromous maternal traits provide offspring with an adaptive advantage and greater fitness in early ontogeny, and that a small number of anadromous females (six of 96 adults sampled) are the main drivers of reproduction in this system.

Individual, social, and sexual niche traits affect copulation success in a polygynandrous mating system

In polygynandrous mating systems, the factors that mediate copulation success and the use of alternative mating tactics, such as mate guarding, are still poorly understood. In the rock hyrax (Procavia capensis), both sexes mate annually with multiple partners during a single month. In order to examine the factors that drive copulation success, we used 494 mating-related observations that were collected over a decade. In our analysis, we used the traits of individual hyraxes as well as the traits of members of their sexual niche, which we defined as their local competitors and potential mates. Using individual traits, we found that overall, female hyraxes rejected copulation attempts more frequently than males, supporting predictions from sexual selection theory. Females who had been mothers in previous years were mate-guarded more by resident males. When we considered the traits of competitors and potential mates in individuals’ sexual niche, we found that when resident males had higher-ranking competitors, their copulation success decreased, irrespective of their own traits. Bachelor male copulation success was not influenced by their competitor’s social status. Female copulation success was positively affected by maternal status and by social network position. Females that were central in the social network and those that had central female competitors had higher copulation success, supporting the benefits of social cohesion and the importance of the social niche. Thus, our results suggest that in polygynandrous mating systems, copulation success is determined not only by individual quality but also by the social and sexual niches that the individual occupies. Social networks describe with whom individuals consort. The complex patterns of sexual relationships in animal societies can also be expressed as networks of mating-related interactions. During our long-term study on the dynamic social relationships of wild rock hyraxes, we observed complex sexual interactions. Our results show that hyraxes choose mating partners from their available mate pool (or sexual niche) taking into account the traits of their actual mates, other potential mates, and those of their competitors. These findings suggest that the sexual niche, describing the subset of available mating partners, is important for mate choice, with significant implications to the study of sexual selection.

The influence of female presence and seasonality on the home range size and activity patterns of male domestic cats in Brazil’s Atlantic Forest

The factors that affect the home range size of domestic cats (Felis silvestris catus) in a semi-domesticated condition (i.e., cats that receive shelter and food from humans but are free to move in the wider natural environment) is not completely understood. Here, using radio telemetry, we present the first assessment of the home range size and activity patterns of male domestic cats living in the insular environment of Brazil’s Atlantic Forest, and examine the extent to which these were influenced by the presence (‘resident males with females’: RMF group) or absence (‘single males’: SM group) of females in the residences of their owners. Daily and seasonal activity patterns have also been characterized. Home ranges of the RMF were markedly smaller than that of the SM and exhibited less overlap with the home ranges of other males than did those of the SM. Male cats were most active at twilight and evening (44.68 ± 1.07) and least active in the afternoon (28.76 ± 2.79). RMF presented nocturnal activity greater than SM, especially in the dry season. Our data indicate that presence of females is an important factor in shaping these parameters of domestic male cats.

Size matters: Scale mismatch between space use patterns of tigers and protected area size in a Tropical Dry Forest

India harbours the largest wild tiger population in the world and Tropical Dry Forest areas constitute the largest habitat for them. Recent extinctions, however, from two high profile tiger reserves, highlight the vulnerability of tiger in this habitat. Our examination of historic range areas for tigers shows that populations are disappearing at a faster rate in Tropical Dry Forest (64% sites suffering local extinction in 100years) than in any other suitable habitat in India. Focusing on data from the Tropical Dry Forest of Panna Tiger Reserve in central India, we examine the spatial ecology of the tiger population prior to its local extinction. We analyse home range sizes, overlaps and shifts, as well as the range expansion and contraction of radio-collared tigers between 1996 and 2005. In this reserve, the average annual home range sizes for both males (n=2) and females (n=4) were three to four times larger than those reported so far from other tropical habitats in India — male: mean 179.3±11.8km2 (95% Fixed kernel; n=7); female: mean 46.6±3.7km2; (95% Fixed kernel; n=16). Adult female home ranges were exclusive and overlapped little with neighbouring female ranges (3±1.46%, n=6). Male home ranges were not exclusive: resident floater males shared space with territorial males and mated with resident females. Home ranges of all breeding radio-collared tigers extended beyond the protected area boundary and were exposed to edge effects that exist at the periphery and outside. With such spatial use patterns, security and management measures provided within the boundary are unlikely to be very successful in protecting the population. Protected Areas in Tropical Dry Forest across India are relatively small (366.92±422.12km2 SD) and historical trends point towards a scale-mismatch that exists between the size of Protected Areas and the space use requirements of tigers. This scale mismatch adds to the vulnerability of existing small populations and perhaps explains why tiger populations in Tropical Dry Forest have disappeared at a faster rate than in any other tiger habitat of the sub-continent.

Black-capped chickadees, Poecile atricapillus, avoid song overlapping: evidence for the acoustic interference hypothesis

Many animals produce sounds that overlap the sounds of others. In some animals, overlapping is thought to be an aggressive signal important in resource defence. Yet, overlapping can also occur by chance, and therefore its function is controversial. In this study, we conducted two experiments to test the function of overlapping in black-capped chickadees, Poecile atricapillus. In experiment 1, we simulated territorial intrusions by broadcasting songs inside established chickadee territories. Resident males overlapped the playback-simulated intruders significantly less than expected by chance, as in most species in which overlapping has been described. Chickadees also overlapped more when they were farther from the intruder. This pattern suggests that chickadees avoid overlapping as a mechanism for reducing acoustic interference (‘interference avoidance hypothesis’). However, the pattern could also constitute submissive signalling if chickadees signal de-escalation (associated with greater distance between opponents) through increasing rates of overlapping (‘submissive signalling hypothesis’). Therefore, in experiment 2, we contrasted these two hypotheses by comparing responses to playback stimuli with low or high interference potential and low or high signal value. We manipulated interference potential by broadcasting stimuli at different amplitudes. We manipulated signal value by broadcasting either song stimuli, which elicit aggression, or white noise stimuli with matching time-amplitude characteristics. If overlapping is a submissive signal, then we predicted that chickadees would avoid overlapping song stimuli, but not white noise stimuli, which lack signal value. Contrary to this prediction, chickadees overlapped song and white noise stimuli equally often, but significantly less often than expected by chance. Furthermore, chickadees overlapped both types of stimuli more often when they were broadcast at lower amplitudes (i.e. lower interference potential). Together, these findings provide compelling evidence that overlapping is not a signal in this species, and that chickadees avoid overlapping both biotic and abiotic sounds as a mechanism for reducing interference.

Territoriality in the tompot blenny Parablennius gattorugine from photographic records.

The behaviour of the tompot blenny Parablennius gattorugine was studied from a long-term underwater photographic record from two sites on the south-west coast of the U.K. Repeated observations of individually identifiable P. gattorugine during 112 dives revealed that male P. gattorugine may guard eggs in a particular crevice over subsequent breeding seasons, reside in the same location for up to 4 years and recover from injuries received in disputes over territory. Further observations included resident males wiping eggs with greatly expanded anal glands, adult-type fighting between juveniles and unusual behaviour where a large male manipulated an empty mollusc shell for the attention of two smaller conspecifics.

Male size and territoriality in the cicada killer wasp Sphecius speciosus (Hymenoptera: Crabronidae)

ABSTRACTMales of the eastern cicada killer wasp, Sphecius speciosus, occupy territories in which they may hover or where they may perch either in trees near one or more emergence holes or on the ground at these spots from which females may emerge. Large males are more likely to hold and defend these territories at a site in northern Virginia. When resident males were captured, held and weighed, the males that replaced them, which were also captured, held and weighed, had significantly lower body weights on average than the residents.

Breaking the succession rule: the costs and benefits of an alpha-status take-over by an immigrant rhesus macaque on Cayo Santiago

Explaining intraspecific variation in reproductive tactics hinges on measuring associated costs and benefits. Yet, this is difficult if alternative (purportedly less optimal) tactics remain unobserved. We describe a rare alpha-position take-over by an immigrant male rhesus macaque in a population where males typically gain rank via succession. Unusually, male aggressiveness after the take-over correlated with rank and mating success. The new alpha achieved the highest mating and reproductive success. Nevertheless, he sired only 4 infants due to high extra-group paternity (59.3%). The costs of his immigration tactic were high: after the mating season ended, unable to deter coalitionary attacks by resident males, he was overthrown. The following year he had the highest relative annual weight loss and levels of immune activation among males in the group. Succession-based rank-acquisition in large, provisioned groups of macaques thus appears to be actively maintained by resident males, who impose high costs on challengers.

Nesting phenology, mate choice, and genetic divergence within a partially migratory population of American Kestrels

ABSTRACT Studies across annual cycles are important for understanding the consequences of carryover effects and predicting species' responses to environmental change. Partially migratory populations, which consist of resident and migratory individuals, are excellent systems for studying how wintering strategies may affect reproduction. We examined whether wintering strategy (residency or nonresidency) created temporal divides in egg-laying date within a local breeding population of American Kestrels (Falco sparverius) and thus led to assortative mating and genetic divergence between early- and late-breeding birds. For 3 yr, we trapped and marked kestrels in winter and recaptured mated pairs in nest boxes in the subsequent spring. We then genotyped early- and late-breeding kestrels using 6 polymorphic microsatellite loci. Residents nested earlier than nonresidents, but not after the warmest and driest winter of the study. Resident females were more likely to mate with resident males than nonresident males,...

Individual participation in intergroup contests is mediated by numerical assessment strategies in black howler and tufted capuchin monkeys.

Asymmetries in resource-holding potential between opposing groups frequently determine outcomes of intergroup contests. Since both numerical superiority and high intergroup dominance rank may confer competitive advantages, group members should benefit from assessing the relative strength of rivals prior to engaging in defensive displays. However, differences in individual assessment may emerge when cost-benefit trade-offs differ among group members. We examine the influence of numerical superiority and intergroup dominance relationships on individual participation in intergroup encounters in black howler monkeys (Alouatta pigra) and tufted capuchin monkeys (Sapajus nigritus). Black howlers responded with longer vocal displays during encounters with neighbours with an equal number of resident males, while tufted capuchins increased their participation with increasing relative male group size. Within each species, males and females responded similarly to varying numerical odds, suggesting that despite pay-off asymmetries between males and females, both sexes were similarly influenced by numerical asymmetries in deciding to participate in collective group defence. Whereas the outcome of contests among tufted capuchins was determined by relative male group size, reflected in a pronounced intergroup dominance hierarchy, the absence of dominance relationships among black howler groups may have provoked prolonged vocal displays in order to assess rival groups with matching competitive abilities.

Territorial clashes in the Neotropical butterfly Actinote pellenea (Acraeinae): do disputes differ when contests get physical?

In many animals, males interact with or without physical contact to contest the possession of mating sites. The winner in such interactions often has larger body size and is the individual that previously occupied the territory (the resident). However, there is little consensus among studies on territorial insect species concerning which traits determine individual fighting ability, and why residency increases the chances of victory. We studied the butterfly Actinote pellenea to evaluate the hypothesis that stronger males are more likely to become residents, and that traits functionally related to behaviors adopted during contests should be important determinants of fighting ability. Males of A. pellenea grapple in the air and fall to the ground during combat. Therefore, we predicted that traits related to physical strength should be the most important determinants of the outcome of contests. To test our hypothesis, we observed fights between resident and intruder males, and fights in which both rivals were induced to behave as residents. We found that physical fighting was more likely when both rivals behave as residents. In addition, wing length and body mass were more closely related to contest success than age. Our results indicate that previous residency increases male motivation to fight, and that stronger individuals become residents. Although butterflies are considered weaponless, we suggest that traits important to contest resolution change according to behaviors adopted during disputes.

The Role of Scent Marking in Mate Selection by Female Pumas (Puma concolor)

Mate selection influences individual fitness, is often based on complex cues and behaviours, and can be difficult to study in solitary species including carnivores. We used motion-triggered cameras at 29 community scrapes (i.e. scent marking locations used by multiple individuals) and home range data from 39 GPS-collared pumas (Puma concolor) to assess the relevance of communication behaviours for mate selection by female pumas in California. Female pumas visited community scrapes irregularly and visitation bouts appeared to be correlated with oestrus. Female pumas on average selected from 1.7 collared males, and selection was based on multiple cues that varied among the different time periods measured (i.e. the female’s visitation bout and in 90 days previous to the consorting event). Female mate selection over the course of a visitation bout was based on frequency of the male visitation, mass, and age. In the 90 days previous to consorting, the number of scrapes a male created was the most important contributor to selection, which was likely related to his residency status. We also found that at least 14% of females mated with multiple males, thus possibly confusing paternity. Our findings provide a mechanistic understanding of how female pumas use scent and auditory communication at community scrapes to select dominant resident males to mate with.