Resident Males Research Articles

Post-release breeding of translocated sharp-tailed grouse and an absence of artificial insemination effects

Context Translocation has become a widely used method to restore wildlife populations following extirpation. For some species, such as lekking grouse, which breed at traditional mating grounds, reproduction is linked to culturally established geographic locations. Cultural centres are lost upon extirpation, making restoration into otherwise rehabilitated habitats especially challenging. The process by which species with culturally dependent reproduction sometimes become re-established is poorly understood and merits investigation to improve conservation strategies. Historically, population restoration of North American lekking grouse (Tympanuchus spp. and Centrocercus spp.) via translocation has yielded poor results, in part because translocation sites lack leks, culturally determined breeding locations for which breeding adults form a high degree of philopatry. Columbian sharp-tailed grouse (Tympanuchus phasianellus columbianus; CSTG) occurs in <10% of its historic range, but the existence of rehabilitated historic habitat provides for the potential of population restoration via translocation. Aims We reintroduced CSTG to vacant habitat in north-central Nevada, USA, from 2013 to 2017, with concordant goals of promoting females to nest and males to lek. We tested the utility of performing artificial insemination (AI) on females before translocation and we conducted paternity analyses to understand male reproduction. Methods We monitored females for the effects of AI on nest initiation, nest survival and egg fertility. We used post-hatch extra-embryonic membranes and other tissues to evaluate paternity of chicks produced at the restoration site. Key results Artificial insemination had no effect on female survival or nest initiation, and did not fertilise any eggs within nine sampled clutches (n=102 eggs). Most paternity was attributable to male residents that had survived for ≥1 year at the restoration site before the arrival of translocated females. Conclusions Artificial insemination neither aided nor harmed female reproduction. A small number of translocated, resident adult males sired reproduction following female release. Implications The presence of resident males at restoration sites may be more likely to result in post-translocation reproduction than is pre-translocation AI. Restoring CSTG to vacant habitat should focus on translocating females into suitable nesting habitat while simultaneously ensuring that reproductively capable males are available within or adjacent to the nesting habitat.

Reproductive Behavior of the Amazonian Nurse-Frog Allobates paleovarzensis (Dendrobatoidea, Aromobatidae)

Allobates paleovarzensis is a diurnal leaf-litter anuran of the Dendrobatoidea superfamily inhabiting Amazonian forests. Based on behavioral field observations, conducted between 2008–2017 at three localities, we describe the courtship, mating, parental care behavior and territoriality of the species. Vocal activity is more intense in the morning and during the rainy season. Resident males respond aggressively to other males that invade their territories, whereas females are not territorial. Females are attracted by the advertisement call of males and enter their territories to breed. The male courtship call has a lower frequency than the advertisement call, indicating that males can modulate the frequency characteristics of their vocalizations. Amplexus stimulates the release of oocytes by females. Males attend multiple egg clutches within their territories and transport tadpoles on their backs to aquatic habitats. Males carry up to 60 tadpoles on a single transport event—the largest number ever recorded for Allobates. We did not record male nor female cannibalism of tadpoles. In summary, we found that Allobates paleovarzensis is a polygamous species with uniparental care performed by the male, complex courtship behavior, high fecundity, and territoriality related to male competition for space and females.

Social networks predict immigration success in wild Japanese macaques.

Male migration is common in mammals and comes with associated benefits and costs. Male-male affiliative relationships are behavioural strategies that migrating males can adopt in order to maximise benefits and minimize costs. While we know that such strategies primarily serve to reduce tension, little is known about how they actually affect male immigration success. We investigated the influence of male-male affiliative relationships on immigration success in a group of wild Japanese macaques (Macaca fuscata). We used social network analysis to examine the distribution of male-male affiliative interactions and their association with immigration success. We found that visiting males with high eigenvector centralities and low weighted degree centralities were more likely to be integrated into the group. Other factors such as season, age-class, and dominance rank amongst visiting males did not affect male integration success. Our results suggest that strong male affiliative bonds and a centralized position within the male-male grooming network can predict future integration success of visiting males into a social group through promoting higher tolerance of resident males and reducing aggression risks.

Male courtship preference during seasonal sympatry may maintain population divergence.

Animal migration can lead to a population distribution known as seasonal sympatry, in which closely‐related migrant and resident populations of the same species co‐occur in sympatry during part of the year, but are otherwise allopatric. During seasonal sympatry in early spring, residents may initiate reproduction before migrants depart, presenting an opportunity for gene flow. Differences in reproductive timing between migrant and resident populations may favor residents that exhibit preferences for potential mates of similar migratory behavior and reproductive timing, thus maintaining population divergence. We studied dark‐eyed juncos (Junco hyemalis), a songbird that exhibits seasonal sympatry. We conducted simulated courtship interactions in which we presented free‐living resident males with either a caged migrant or resident female and quantified courtship behavior prior to the departure of the migrants. We found that resident males preferred to court resident females: they sang more short‐range songs and exhibited more visual displays associated with courtship when presented with resident females. We conclude that males distinguish between migrant and resident females during seasonal sympatry when the risk of interacting with non‐reproductive, migrant females is high. Male mate choice in seasonal sympatry is likely adaptive for male reproductive success. As a secondary effect, male mating preference could act to maintain or promote divergence between populations that differ in migratory strategy.

Iteroparity of stream resident masu salmon Oncorhynchus masou.

The degree of iteroparity in stream-resident forms of masu salmon Oncorhynchus masou was examined using mark-recapture studies in natural streams. In a partially migratory population, at least 10% of resident males survived after maturation and repeatedly matured for up to 5 years. In the landlocked amago salmon subspecies, the post-maturation survival rate was at least 7% and repeat maturation was observed for up to 3 years for both males and females.

From ornament to armament or loss of function? Breeding plumage acquisition in a genetically monogamous bird.

The evolution of conspicuous male traits is thought to be driven by female mate choice or male-male competition. These two mechanisms are often viewed as distinct processes, with most studies focusing on female choice. However, both mechanisms of sexual selection can act simultaneously on the same trait (i.e., dual function) and/or interact in a synergistic or conflicting way. Dual-function traits are commonly assumed to originate through male-male competition before being used in female choice; yet, most studies focusing on such traits could not determine the direction of change, lacking phylogenetic information. We investigated the role of conspicuous male seasonal plumage in male-male competitive interactions in the purple-crowned fairy-wren Malurus coronatus, a cooperatively breeding bird. Male breeding plumage in most Malurus species is selected by female choice through extra-pair mate choice, but unlike its congeners, M.coronatus is genetically monogamous, and females do not seem to choose males based on breeding plumage acquisition. Our study shows that, within groups, subordinate males that were older, and therefore higher-ranked in the queue for breeder position inheritance, produced a more complete breeding plumage. In line with this, subordinate males that were older and/or displayed a more complete breeding plumage were more successful in competitively acquiring a breeder position. A role as a signal of competitive ability was experimentally confirmed by presenting models of males: in breeding colours, these received more aggression from resident breeder males than in nonbreeding colours, but elicited limited response from females, consistent with competitors in breeding plumage being perceived as a bigger threat to the breeder male. The role of the conspicuous breeding plumage in mediating male-male interactions might account for its presence in this genetically monogamous species. As phylogenetic reconstructions suggest a past female choice function in M.coronatus, this could represent a sexual trait that shifted functions, or a dual-function trait that lost one function. These evolutionary scenarios imply that intra- and intersexual functions of ornaments may be gained or lost independently and offer new perspectives in understanding the complex dynamics of sexual selection.

The unexpected genetic mating system of the red-backed toadlet (Pseudophryne coriacea): A species with prolonged terrestrial breeding and cryptic reproductive behaviour.

Molecular technologies have revolutionized our classification of animal mating systems, yet we still know very little about the genetic mating systems of many vertebrate groups. It is widely believed that anuran amphibians have the highest reproductive diversity of all vertebrates, yet genetic mating systems have been studied in <1% of all described species. Here, we use single nucleotide polymorphisms to quantify the genetic mating system of the terrestrial breeding red-backed toadlet Pseudophryne coriacea. In this species, breeding is prolonged (approximately 5months), and males construct subterranean nests in which females deposit eggs. We predicted that females would display extreme sequential polyandry because this mating system has been reported in a closely related species (P.bibronii). Parentage analysis revealed that mating success was heavily skewed towards a subset of males (30.6% of potential sires) and that nearly all females (92.6%) mated with one male. In a high percentage of occupied nests (37.1%), the resident male was not the genetic sire, and very few nests (4.3%) contained clutches with multiple paternity. Unexpectedly, these results show that sequential polyandry is rare. They also show that there is a high frequency of nest takeover and extreme competition between males for nest sites, but that males rarely sneak matings. Genetic analysis also revealed introgressive hybridization between P.coriacea and the red-crowned toadlet (Pseudophryne australis). Our study demonstrates a high level of mating system complexity, and it shows that closely related anurans can vary dramatically in their genetic mating system.

Queuing, takeovers, and becoming a fat cat: Long‐term data reveal two distinct male spatial tactics at different life‐history stages in Namibian cheetahs

AbstractIn mammals, male spatial tactics and sociality can be predicted from the size, degree of overlap and ease of defense of female individual or group home ranges (HRs). An exception is apparently the cheetah (Acinonyx jubatus) for which studies from East Africa describe a socio‐spatial organization where resident males defend small territories, which cover a portion of large ranges of solitary females, and non‐territorial males (floaters) roam over vast areas whilst queuing for access to territories. Most studies from southern Africa did not report the existence of territorial males and floaters, but a system with both males and females roaming over vast areas with overlapping HRs. Here, we derive and test predictions from previously described spatial tactics in felids by studying the movements, behavior, and/or physical characteristics of 164 radio‐collared Namibian cheetahs on commercial farmland from 2002 to 2014. The results demonstrate the existence of male territory holders and floaters and a, by mammalian standards, unique sociality in that commonly groups of males, sometimes solitary males defended small areas partially overlapping with large ranges of solitary females. When a solitary male or a group of males switched between both tactics, floating usually preceded territory holding, suggesting that both spatial phases are equivalent to distinct life‐history stages. Switching from roaming as a floater to holding a territory was also associated with an increase in body mass index (BMI) and a change in the observed behavior of animals captured in traps when approached by humans. Both BMI and this behavior are therefore reliable, quick biomarkers of an individual's space use tactic and life‐history stage. We elaborate the implications of this socio‐spatial organization for models of ecological movements and on conflict mitigation measures such as translocations or the planning of future protected areas. We suggest that such implications also apply to other species where one sex exhibits two space use tactics and two sets of range sizes.

Male and female signaling behavior varies seasonally during territorial interactions in a tropical songbird

In many tropical birds, both sexes use conspicuous vocal signals during territorial interactions. Although a growing number of studies examine male and female signals in the context of coordinated vocal duets, the use of vocal signals by both sexes in non-duetting species is poorly documented, even though these species are more numerous than duetting species. Furthermore, few studies of tropical non-duetting species test for seasonal variation in signaling behavior. We studied season-specific and sex-specific variation in signaling behavior of a tropical resident songbird, the Rufous-capped Warbler (Basileuterus rufifrons), by conducting a playback experiment where we simulated conspecific territorial intruders producing three types of vocalizations (male songs, female calls, or a “pair” with simultaneous male songs and female calls) and a heterospecific control. We repeated playback during the pre-breeding and breeding seasons. Response intensity to playback varied with season and sex of the focal birds. During the pre-breeding season, both sexes showed strong physical approach responses and vocal responses to all conspecific intrusions, especially paired intrusions. During the breeding season, males responded strongly to all conspecific treatments, whereas females showed little response. Although females primarily used calls in response to conspecific playback, many females also sang, especially during the non-breeding season. Our results therefore suggest that both male and female signals are used for shared territory defense, but that the contributions of each sex to territory defense vary seasonally. Our results also contribute to our understanding of the evolution of combined male and female signaling during territory defense. In resident tropical animals, both males and females often use conspicuous signals during territorial interactions with conspecifics. Seasonal and sex-specific variation in vocal behavior of tropical resident birds during these territorial interactions has received little research attention. We conducted a playback experiment to investigate season- and sex-specific variation in signaling behavior of tropical Rufous-capped Warblers (B. rufifrons). In the pre-breeding season, both sexes responded strongly to all conspecific intrusions, especially paired intrusions, by approaching the playback speakers and vocalizing. In the breeding season, males actively defended the territory alone whereas females rarely responded. Our results suggest that both sexes of Rufous-capped Warbler use vocal signals for shared territory defense, although the contributions of each sex to territory defense differ seasonally.

Anchoring and adjusting amidst humans: Ranging behavior of Persian leopards along the Iran-Turkmenistan borderland.

Understanding the space use and movement ecology of apex predators, particularly in mosaic landscapes encompassing different land-uses, is fundamental for formulating effective conservation policy. The top extant big cat in the Middle East and the Caucasus, the Persian leopard Panthera pardus saxicolor, has disappeared from most of its historic range. Its spatial ecology in the areas where it remains is almost unknown. Between September 2014 and May 2017, we collared and monitored six adult leopards (5 males and 1 female) using GPS-satellite Iridium transmitters in Tandoureh National Park (355 km2) along the Iran-Turkmenistan borderland. Using auto-correlated Kernel density estimation based on a continuous-time stochastic process for relocation data, we estimated a mean home range of 103.4 ± SE 51.8 km2 for resident males which is larger than has been observed in other studies of Asian leopards. Most predation events occurred in core areas, averaging 32.4 ± SE 12.7 km2. Although neighboring leopards showed high spatiotemporal overlap, their hunting areas were largely exclusive. Five out of six of leopards spent some time outside the national park, among human communities. Our study suggests that a national park can play an ‘anchoring’ role for individuals of an apex predator that spend some time in the surrounding human-dominated landscapes. Therefore, we envisage that instead of emphasizing either land sharing or land sparing, a combined approach can secure the viability of resilient large carnivores that are able to coexist with humans in the rugged montane landscapes of west and central Asia.

Persistent escalation of alcohol consumption by mice exposed to brief episodes of social defeat stress: suppression by CRF-R1 antagonism.

Episodic bouts of social stress can precede the initiation, escalation, or relapse to disordered alcohol intake. Social stress may engender neuroadaptations in the hypothalamic-pituitary-adrenal (HPA) axis and in extrahypothalamic stress circuitry to promote the escalation of alcohol intake. We aimed to (1) confirm a pattern of escalated drinking in socially defeated mice and to (2) test drugs that target distinct aspects of the HPA axis and extrahypothalamic neural substrates for their effectiveness in reducing murine, stress-escalated drinking. Male C57BL/6J (B6) mice were socially defeated by resident Swiss-derived males for ten consecutive days receiving 30 bites/day. Ten days after the final defeat, cohorts of B6 mice received continuous or intermittent access to 20% EtOH (w/v) and water. After 4weeks of drinking, mice were injected with weekly, systemic doses of the CRF-R1 antagonist, CP376395; the glucocorticoid receptor antagonist, mifepristone; the 11-beta-hydroxylase inhibitor, metyrapone; or the 5-alpha-reductase inhibitor, finasteride. Prior to drug treatments, defeated mice reliably consumed more EtOH than non-defeated controls, and mice given alcohol intermittently consumed more EtOH than those with continuous access. CP376395 (17-30mg/kg) reduced continuous, but not intermittent EtOH intake (g/kg) in socially defeated mice. Mifepristone (100mg/kg), however, increased drinking by defeated mice with intermittent access to alcohol while reducing drinking during continuous access. When administered finasteride (100mg/kg) or metyrapone (50mg/kg), all mice reduced their EtOH intake while increasing their water consumption. Mice with a history of episodic social defeat stress were selectively sensitive to the effects of CRF-R1 antagonism, suggesting that CRF-R1 may be a potential target for treating alcohol use disorders in individuals who escalate their drinking after exposure to repeated bouts of psychosocial stress. Future studies will clarify how social defeat stress may alter the expression of extrahypothalamic CRF-R1 and glucocorticoid receptors.

Home sweet home: social dynamics and genetic variation of a long-term resident bottlenose dolphin population off the Chilean coast

CONICYT Postdoctoral FONDECYT Program 3140513 CONICYT Iniciacion 11170182 FONDECYT 1140548 ICM P05-002 PFB 023

Ecological Forms of Black Sea Brown Trout (Salmo trutta labrax) in the Mzymta River as Manifestation of Ontogenetic Plasticity

Populations of brown trout in the Mzymta River and its tributaries include anadromous (mainly female) and resident (mainly males) fish. Some resident males in the basin of the Mzymty River attain sexual maturity at the age 1+, and resident females mature at the age 2+ or 3+. The maximum age of resident fish is 4+ in the samples studied. Migrations of anadromous brown trout to the sea occur at the ages 1+, 2+, or 3+. Future spawners spend from 1 to 4 years at feeding grounds in the sea. Smolts of the population are characterized by performing not only spring but also autumn migrations to the sea. One smolt specimen has been detected upstream from the dam in the river where spawners of anadromous brown trout do not migrate; this means that the capability for sea migrations persists long in the population represented only by resident specimens of brown trout. The diversity of life cycles and ecological forms in populations of brown trout is not lower than in populations of brown trout in Northern and Western Europe. The comparison of the data obtained with published data makes it possible to come to the conclusion about the high plasticity of ontogenesis of Black Sea brown trout.

Lion population dynamics: do nomadic males matter?

Key population processes are sometimes driven by male dynamics, but these drivers are often overlooked because of the scale over which they operate. Lions (Panthera leo) provide an ideal case study for investigating factors governing male dynamics and their influence on population sustainability. Lions display sexually selected infanticide, and resident males must defend their offspring from nomads that may have dispersed over long distances; factors affecting male–male competition over large spatial scales can have population wide consequences. We report here on the first systematic analysis of long-term individual-based data of male lions in the Serengeti National Park, Tanzania. From 1974 to 2012, we observed 471 coalitions (796 males) in our study area. We investigate factors affecting male immigration and the impacts on the resident population. The yearly number of nomadic males entering the study population affected cub survival and mating access. Success rates of nomadic males gaining tenure with a pride increased with age and coalition size. We observed a significant decline in male immigration, which resulted in lowered levels of male replacement in the study population, reduced infanticide, and greater cub survival. The decline in incoming males likely resulted from increased anthropogenic pressures in surrounding areas. Conversely, the core study population was largely buffered from anthropogenic threats and likely served as a source to neighboring sinks. Reduced infanticide in the core population might have compensated for rising lion mortalities in surrounding areas, but as human-wildlife conflicts intensify with the rapidly growing human population, compensatory mechanisms may become overwhelmed.

Trace organic contaminant (TOrC) mixtures in Minnesota littoral zones: Effects of on-site wastewater treatment system (OWTS) proximity and biological impact

On-site wastewater treatment systems (OWTSs) are an international wastewater management strategy for rural and semi-rural communities without access to centralized sewage treatment. These systems are a suspected source of trace organic contaminants (TOrCs) that may be responsible for endocrine disrupting effects to resident fish species in Minnesota Lakes. This study assessed localized porewater concentrations of TOrCs in near-shore environments across five Minnesota Lakes. Sampling sites were designated as either likely (HOME) or unlikely (REF) to receive OWTS discharges based on their proximity to shoreline households. Sampling sites also served as sunfish spawning habitats concurrently studied for biological impacts to resident adult males. Two-group hypothesis tests demonstrated significantly (p = .02) higher total TOrC concentrations in HOME (Mean = 841 ng/L) versus REF (Mean = 222 ng/L) sites. HOME sites also contained a wider suite of TOrC detections relative to REF sites. The distance to the nearest household (most proximal distance; MPD) negatively correlated (r = −0.62) with total TOrC concentrations. However, 2,4-D and DEET were major contributors to these total concentrations, suggesting that anthropogenic influence from households may not be exclusively attributed to OWTS discharges. Further, TOrC presence and elevated nitrogen concentrations in REF site porewater suggest additional, non-household TOrC discharges to these lakes. Significantly higher blood concentrations of vitellogenin (p = .03) and 11-ketotestosterone (p = .01) were observed in adult male sunfish captured from HOME versus REF sites. Comparisons between chemical and biological data indicate enhanced bioactive effects of co-contaminants. The findings from this study demonstrate multiple diffuse transport pathways contribute to the presence of biologically active TOrC mixtures in Minnesota Lakes, and mitigation efforts should consider minimizing residential inputs of chemicals associated with both outdoor and OWTS activity.

Listening in the bog: I. Acoustic interactions and spacing between males of Sphagniana sphagnorum

Males of the katydid Sphagniana sphagnorum form calling aggregations in boreal sphagnum bogs to attract mates. They broadcast frequency-modulated (FM) songs in steady series, each song comprised of two wing-stroking modes that alternate audio and ultrasonic spectra. NN analysis of three populations found mean distances between 5.1 and 8.4 m, but failed to find spacing regularity: in one males spaced randomly, in another they were clumped, but within the clumps spaced at random. We tested a mechanism for maintaining inter-male distances by playback of conspecific song to resident males and analysing song interactions between neighbouring males in the field. The results indicate that the song rate is an important cue for males. Information coded in song rates is confounded by variation in bog temperatures and by the linear correlation of song rates with temperature. The ultrasonic and audio spectral modes suffer different excess attenuation: the ultrasonic mode is favoured at shorter distances (< 6 m), the audio mode at longer distances (> 6 m), supporting a hypothesized function in distance estimation. Another katydid, Conocephalus fasciatus, shares habitat with S. sphagnorum and could mask its ultrasonic mode; however, mapping of both species indicate the spacing of S. sphagnorum is unaffected by the sympatric species.

Management of Bicytopenia using metal based Ayurvedic formulations

Bicytopenia is a disorder of hematopoietic system and is reflected by lowering of any two of hemoglobin (below 10 g/dL), white cells (3.5-10.5 billion cells/L) and platelets (below 100 × 109/L) in peripheral blood. It is usually treated using corticosteroids, growth factors, immune-suppressants, nutritional supplements, periodical blood transfusion and bone marrow transplantation. However, these treatments have limited effects and may cause moderate to severe side-effects. A young Non Resident Indian male of 28 years old opted for Ayurvedic treatment for Bicytopenia as first choice of treatment, with the consent of a leading oncologist. The patient was prescribed a combination of Herbo-Mineral Formulations (HMFs) along with a regulated diet and lifestyle. Patient has completed fourteen months of Ayurvedic treatment and now leads a normal life. No adverse effects were noticed during the treatment and follow-up period too. Further controlled pilot studies are required to establish proof of efficacy in a systematic way.

The function of ultrasonic vocalizations during territorial defence by pair-bonded male and female California mice

Acoustic communication is vital to complex social behaviours such as territorial defence. The use of ultrasonic vocalizations, particularly in territorial defence by monogamous species and females, remains understudied. We studied ultrasonic vocalization production and associated aggression in the monogamous, biparental and territorial California mouse, Peromyscus californicus, in which both males and females were found to display similar levels of physical aggression against same-sex intruders. We identified specific ultrasonic vocalization calls that are modulated based on social context: (1) sustained vocalizations, which are long, low-bandwidth calls ranging from 22 to 25 kHz, and (2) barks, which are short, high-intensity calls beginning and ending in the audible range. Despite similarities in physical aggression, sex differences emerged in vocal communication. Only resident males, and not females, produced sustained vocalizations prior to the onset of physical aggression, and were found to shorten the duration of individual sustained vocalization calls over both the course of the pre-encounter phase and from the pre-encounter to encounter phase. In addition, the degree of sustained vocalization shortening in males predicted offensive aggression of the resident. Males exhibited shorter sustained vocalization calls during encounters than females. Barks occurred more frequently during female–female physical aggression than in male–male encounters, and correlated highly with defensive aggression by intruders. Finally, a newly identified highly complex call, sweep phrases, was recorded in a subset of both sexes in the pre- and post-encounter phases. The overall results indicate that ultrasonic vocalizations may play an important role in territorial defence during both territorial advertisement and aggression in a monogamous rodent. Overall, this monogamous species showed sex similarities in physical aggression but sex differences in vocal communication and a more sophisticated function for sustained vocalizations than previously recognized.

Skin temperature and reproductive condition in wild female chimpanzees.

Infrared thermal imaging has emerged as a valuable tool in veterinary medicine, in particular for evaluating reproductive processes. Here, we explored differences in skin temperature of twenty female chimpanzees in Budongo Forest, Uganda, four of which were pregnant during data collection. Based on previous literature in other mammals, we predicted increased skin temperature of maximally swollen reproductive organs of non-pregnant females when approaching peak fertility. For pregnant females, we made the same prediction because it has been argued that female chimpanzees have evolved mechanisms to conceal pregnancy, including swellings of the reproductive organs, conspicuous copulation calling, and solicitation of male mating behaviour, to decrease the infanticidal tendencies of resident males by confusing paternity. For non-pregnant females, we found slight temperature increases towards the end of the swelling cycles but no significant change between the fertile and non-fertile phases. Despite their different reproductive state, pregnant females had very similar skin temperature patterns compared to non-pregnant females, suggesting little potential for males to use skin temperature to recognise pregnancies, especially during maximal swelling, when ovulation is most likely to occur in non-pregnant females. We discuss this pattern in light of the concealment hypothesis, i.e., that female chimpanzees have evolved physiological means to conceal their reproductive state during pregnancy.

Male Resource Defence Behaviour Strengthens Harem Size in Promiscuously Mating Fruit Bats

Mating success in group forming animals largely depend on the ability of same-sex competitors (usually males) to monopolize local resources that are spatially limited and are of importance to their sexual partners. Across taxa, this resource defence behaviour (RDB) is predicted to maximize male reproductive success. Although RDB is widely observed in polygynous societies, its significance as an alternative male mating strategy among randomly mating individuals (i.e., promiscuous) is a less explored topic in ethology, especially within Chiroptera. In this study, we elucidate the relationship between RDB (measured here as male tent defence behaviour) and the harem size associated with adult males of Cynopterus sphinx. From 12 independent resident male removal experiments, we found that inter-male aggressive combats often exclusively occur while defending foliage tents in mating seasons. Further, our harem census data of usurper males (during usurpation) and resident males (post release), suggests a significant bias among females to preferentially roost with the resident males. This preferential association between harem females and the resident males that almost always recovers the foliage tent from the usurpers, suggests that C. sphinx harem males use RDB as an alternative mating strategy to monopolize roosting resources and maintain large harems. However, further research is required to identify the direct effects of RDB on individual male reproductive success.