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1.
A fundamental problem in conservation biology is the risk of inbreeding in fragmented and declining populations. In the Hluhluwe-iMfolozi Park (HiP), a small, enclosed reserve in South Africa, a large lion Panthera leo population arose from a founder group of five individuals in the 1960s. The HiP lion population went through a persistent decline and showed indications of inbreeding depression. To restore the genetic variation of the inbred HiP lion population, new lions were translocated into the existing population. Translocated females formed stable associations and established enduring pride areas with other translocated lionesses, but did not bond into native female prides. The translocated male coalition was more successful in gaining and maintaining residence in a pride than the translocated lone male that split off on his own from the male coalition. Litter size and cub survival was about twice as high for pairings involving at least one translocated parent than for pairings of two native lions. It is therefore possible to infuse new genes rapidly and successfully into a small, isolated lion population. Such translocations may become an important adaptive management tool as lion populations become increasingly fragmented.  相似文献   

2.
Habitat selection and feeding ecology of a reintroduced population of cheetahs Acinonyx jubatus were studied in a 16 000 ha game reserve in the Eastern Cape Province (South Africa). Seventy per cent of the reserve is characterized by very dense thicket vegetation (valley bushveld) and the remainder is open and savanna-like. The results illustrated a strong effect of sex and group size on the behaviour of cheetahs. The coalition (three adult males) killed significantly larger animals (55% of kills weighed more than 65 kg) than single female cheetahs (less than 2% of kills weighed more than 65 kg). Female cheetahs showed temporal and spatial avoidance of lions by hunting at dawn and dusk and positioning their home ranges [95% utilization distribution (UDs)] significantly farther from the pride of lions than did the coalition. The coalition hunted earlier and later than female cheetahs, and 46% of their kills were made in darkness. In addition, their home range overlapped that of the lions and they showed neither temporal nor spatial avoidance of the lions. The rates of kleptoparasitism were lower and the kill retention times were longer than those reported elsewhere in Africa, and it is suggested that this is a consequence of the cover provided by the thicket vegetation and prey size. The home ranges (95% UDs) of female cheetahs incorporated more thicket vegetation than that of the coalition, indicating that the coalition is less susceptible to predation than single females. These data suggest that cheetahs possess greater behavioural flexibility than previously reported, that they can hunt successfully in thicket vegetation, sometimes in darkness, that they are not restricted to killing small to medium-sized prey, and that they may not be savanna specialists.  相似文献   

3.
Recently, familial abuse and killing of children have been correlated with infanticidal behavior by nonhuman male animals which is postulated to be genetic. However, infanticide by males as an evolutionary mechanism is unlikely to occur in primates, and is equally unlikely in lions. To investigate the sexual selection hypothesis of infanticide for lions, four questions should be considered: (1) because they all mate freely with lionesses, are male pride lions closely related? (often they are not), (2) do males kill the young cubs when they join a pride? (few such cases have been observed), (3) do the females then mate with the new males to produce offspring? (yes), and (4) do the males remain with the pride for over two years to protect this new generation? (often not). Field data indicate that in NO instance do we know that male lions killed cubs in a new pride, mated with their mother, and then remained with the pride to protect their own young. Rather, female lions may kill more cubs than males and certainly cause many more cub deaths by allowing them to starve, [ infanticide by male lions, infanticide hypothesis, faulty science]  相似文献   

4.
Within‐population studies are needed to investigate the extent of, and the factors underlying, intraspecific variation in home range size. We used data from 12 female and 8 male adult lions instrumented with GPS radio‐collars to describe the ranging behaviour of lions in a population from a dystrophic semi‐arid savanna, Hwange National Park, Zimbabwe. We measured prey availability at the home range scale in 2003, 2004, and 2005. For females, home range size increased as pride biomass increased, which is strongly suggestive of expansionism. Once controlled for pride biomass, home range size decreased as prey biomass increased. Pride ranges responded to changes in food abundance on an annual timescale rather than on a seasonal timescale. Female home range size was influenced by the abundance of kudu in the early dry season, whereas it was influenced by buffalo and young elephant abundance in the late dry season. This study shows that female home range size is mainly driven by the size of the pride, but also by prey abundance. Furthermore, female seasonal home range size may be determined, not only by prey abundance, but also by prey dispersion in the landscape. Home range size of males was driven by both prey biomass and the density of female prides.  相似文献   

5.
非洲狮(Pantheraleo)群处于不断的分裂-聚合过程,其亚群大小与原狮群大小以及诸如狮群捕食成功度、协作幼仔保护及狮群领域防卫等社会性因素有关。我们分析了南非一个保护区(Hluhluwe-Umfolozi公园)15年间的狮群大小,其成年雌狮和成年雄狮群的大小在保护区内呈显著性变化。在开放生境中雌狮结大群,而茂密植被生境中则结小群。雄狮群大小与植被类型无关,但在大的雌狮群分布区域发现大雄狮群。令人惊奇的是,作为幼狮成活率指标的幼狮群大小和雌狮平均幼仔数在保护区内没有显著性差异。我们认为,雌狮群大小的不同是对植被结构的适应,即在开放生境中大群有利于协作狩猎、育幼、共同保护幼仔、应对高强度群间领域防卫竞争。相反,茂密植被中,群间竞争很低,高密度植被覆盖有利于狩猎成功及补偿小狮群对幼仔保护的不足。雌狮平均幼仔数在整个保护区内没有变化,我们认为是由于开放生境和茂密植被对狮群大小起到相似的调节作用  相似文献   

6.
The recent incorporation of molecular methods into analyses of social and mating systems has provided evidence that mating patterns often differ from those predicted by group social organization. Based on field studies and paternity analyses at a limited number of sites, African lions are predicted to exhibit a strict within‐pride mating system. Extra‐group paternity has not been previously reported in African lions; however, observations of extra‐group associations among lions inhabiting Etosha National Park in Namibia suggest deviation from the predicted within‐pride mating pattern. We analysed variation in 14 microsatellite loci in a population of 164 African lions in Etosha National Park. Genetic analysis was coupled with demographic and observational data to examine pride structure, relatedness and extra‐group paternity (EGP). EGP was found to occur in 57% of prides where paternity was analysed (= 7), and the overall rate of EGP in this population was 41% (= 34). Group sex ratio had a significant effect on the occurrence of EGP (< 0.05), indicating that variation in pride‐level social structure may explain intergroup variation in EGP. Prides with a lower male‐to‐female ratio were significantly more likely to experience EGP in this population. The results of this study challenge the current models of African lion mating systems and provide evidence that social structure may not reflect breeding structure in some social mammals.  相似文献   

7.
Sexual segregation (sex differences in spatial organisation and resource use) is observed in a large range of taxa. Investigating causes for sexual segregation is vital for understanding population dynamics and has important conservation implications, as sex differences in foraging ecology may affect vulnerability to area-specific human activities. Although behavioural ecologists have proposed numerous hypotheses for this phenomenon, the underlying causes of sexual segregation are poorly understood. We examined the size-dimorphism and niche divergence hypotheses as potential explanations for sexual segregation in the New Zealand (NZ) sea lion (Phocarctos hookeri), a nationally critical, declining species impacted by trawl fisheries. We used satellite telemetry and linear mixed effects models to investigate sex differences in the foraging ranges of juvenile NZ sea lions. Male trip distances and durations were almost twice as long as female trips, with males foraging over the Auckland Island shelf and in further locations than females. Sex was the most important variable in trip distance, maximum distance travelled from study site, foraging cycle duration and percent time at sea whereas mass and age had small effects on these characteristics. Our findings support the predictions of the niche divergence hypothesis, which suggests that sexual segregation acts to decrease intraspecific resource competition. As a consequence of sexual segregation in foraging ranges, female foraging grounds had proportionally double the overlap with fisheries operations than males. This distribution exposes female juvenile NZ sea lions to a greater risk of resource competition and bycatch from fisheries than males, which can result in higher female mortality. Such sex-biased mortality could impact population dynamics, because female population decline can lead to decreased population fecundity. Thus, effective conservation and management strategies must take into account sex differences in foraging behaviour, as well as differential threat-risk to external impacts such as fisheries bycatch.  相似文献   

8.
African lions (Panthera leo) live in social groups (prides) that exhibit group territorial behavior. Pride persistence is expected to depend on its ability to compete against neighboring prides as well as on average rates of reproduction and survival, thus providing a meaningful measure of intergenerational reproductive success. We used Akaike’s Information Criterion (AIC) to select the best approximating models explaining how demographic variables influenced pride persistence during a 30-year period in the Ngorongoro Crater, Tanzania, and identified landscape factors affecting those demographic variables. Pride persistence to 10 years depended on adult female density (pride size) and cub productivity (the ultimate source of new females). Average age of adult females had a weakly positive influence on pride persistence, while the effect of female mortality was weakly negative. Adult female mortality increased with disease epidemics and in territories with high human disturbance. Cub productivity was highest in territories closest to rivers and only slightly higher near swamps, and also high in areas of higher vegetative cover and high human use. No landscape variable significantly affected female density. The growth and population size of the Crater lions was closely linked to demographic performance of individual prides, while territorial behavior played a key role in mediating the interactive effects of landscape and demography.  相似文献   

9.
Ecologists often describe the foraging ecology of a species as a whole, treating conspecific individuals as ecologically equal. However, individual specialization has potentially important ecological, evolutionary and conservation implications. Foraging studies are usually based on the foraging behaviours of individuals sampled in only 1 year. In this study, the site fidelity of foraging locations of nine female New Zealand sea lions (NZ sea lions Phocarctos hookeri ) from Enderby Island, Auckland Islands, were investigated by repeating their satellite tracking between 1 and 4 years after they were first tracked. Females were monitored during early lactation in the austral summers of 2001–2005. The kernel ranges of females' foraging satellite location concentrations overlapped consistently within and between years. As predicted for benthic foragers, NZ sea lions show low individual variability in foraging behaviour and greater specialization. It is important to understand the spatial and temporal limitations on an individual's foraging-site fidelity, because they can affect a species' ability to cope with environmental changes and anthropogenic impacts. This has significant implications for NZ sea lions management and conservation.  相似文献   

10.
Understanding how animals utilize available space is important for their conservation, as it provides insight into the ecological needs of the species, including those related to habitat, prey and inter and intraspecific interactions. We used 28 months of radio telemetry data and information from 200 kill locations to assess habitat selection at the 3rd order (selection of habitats within home ranges) and 4th order (selection of kill sites within the habitats used) of a reintroduced population of cheetahs Acinonyx jubatus in Phinda Private Game Reserve, South Africa. Along with landscape characteristics, we investigated if lion Panthera leo presence affected habitat selection of cheetahs. Our results indicated that cheetah habitat selection was driven by a trade-off between resource acquisition and lion avoidance, and the balance of this trade-off varied with scale: more open habitats with high prey densities were positively selected within home ranges, whereas more closed habitats with low prey densities were positively selected for kill sites. We also showed that habitat selection, feeding ecology, and avoidance of lions differed depending on the sex and reproductive status of cheetahs. The results highlight the importance of scale when investigating a species’ habitat selection. We conclude that the adaptability of cheetahs, together with the habitat heterogeneity found within Phinda, explained their success in this small fenced reserve. The results provide information for the conservation and management of this threatened species, especially with regards to reintroduction efforts in South Africa.  相似文献   

11.
Social factors influencing reproduction in wild lions   总被引:5,自引:0,他引:5  
The paper summarizes seven years of records of the reproductive history of two wild prides of lions ( Panthera leo L.) in the Serengeti National Park, Tanzania. These records are analyzed to demonstrate ways in which lion reproduction is influenced by their social group and by changes in that group.
Females gave birth at any time of year; they did so sooner if their previous litter died. Females synchronized births with other pride members. Takeover of the pride by new males resulted in a drop in the birth rate. Most cubs died, before two years old. Birth synchrony resulted in better cub survival. The arrival of new males resulted in an increase in cub mortality. Females came into oestrus synchronously with other pride members. Males had a much longer effective reproductive life if they had male companions.
The proximate causes of these features of lion reproduction are considered, and the evolution of aspects of the organization of reproduction in lions is discussed.  相似文献   

12.
The resurrection of Asiatic lions (Panthera leo persica) from the brink of extinction is a remarkable conservation success story. Yet, occurrence of lions as a single population makes them vulnerable to extinction from genetic and environmental factors. Asiatic lions exist as a single free ranging population of 360 individuals in Gir Protected Area (PA; about 290 lions) and surrounding satellite areas (68 lions), namely Girnar Wildlife Sanctuary (WLS), coastal areas, hill ranges extending from Mitiyala-Savarkundla-Palitana-Shihor spreading across Junagadh, Amreli and Bhavnagar districts of Gujarat State, India. This paper traces the conservation history, current conservation pressures, and critically evaluates current conservation planning based on lion ecology and existing anthropogenic pressures. Conservation proposals for translocation of lions to alternate habitats in Kuno WLS and Barda WLS are awaiting final implementation. An alternate initiative is aimed at developing satellite lion habitats, improving corridor connectivity, and facilitating natural dispersal and expansion of lion habitats. The paper evaluates human population living within 2 km boundary of lion habitats and between Gir PA and satellite habitats to show that dispersing lions have to cross heavily populated habitations taking refuge in agriculture fields and scattered forest patches. Satellite habitats vary in size from 18 km2 (Mitiyala WLS) to 250 km2 (scattered forests Hipavadli-Savarkundla-Palitana zone along Shetrunji river) and are inadequate to maintain natural ranging and movement requirements of territorial lions. These habitats are varied in vegetation, terrain, human pressure, and distance to source population. Though satellite lion habitats are important suboptimal habitats for dispersing lions, long-term conservation planning require planned restoration of mosaic habitats for growing populations.  相似文献   

13.
Large carnivores can represent the ultimate challenge for conservation in developed landscapes because of their large area requirements and potential for conflict with humans. Some large carnivores such as mountain lions (Puma concolor) can use a wide range of biomes and vegetation types, and in southern California, USA, they persist in metropolitan Los Angeles, a megacity of 18 million people. Understanding how large carnivores use highly altered landscapes is important for their conservation and management. We estimated home range size, landscape use, and landscape selection for mountain lions in the Santa Monica Mountains and surrounding areas for 29 subadult and adult animals from 2002 to 2016, using 128,133 locations from global positioning system (GPS)-collars. Home range size was similar to that reported by other researchers; home ranges averaged 372 km2 for adult males and 134 km2 for adult females, except for 2 adult males in isolated habitat fragments that maintained 2 of the smallest adult male home ranges ever recorded (24 km2 and 54 km2). Mountain lions very rarely entered developed areas, consistently avoided altered open areas such as golf courses, cemeteries, or other landscaped spaces, and showed a positive relationship between home range size and amount of development, all indicating that developed areas have reduced value for mountain lions. Mountain lions from all sex and age classes selected areas closer to development than expected by chance, which could be related to the presence of mule deer (Odocoileus hemionus) or other prey in or adjacent to urbanization. For 2 adult males that occupied home ranges within the most urban portions of our study area, their response to urban development differed strongly across diurnal periods, ranging from avoidance during the day to selection at night. Shrub vegetation types, especially chaparral, were important in terms of habitat use and resource selection, highlighting their importance for conservation of the species in southern California. North America's largest felid can thrive in shrublands and persist even in one of the world's largest cities, although they only very rarely venture into developed areas within that city. © 2021 The Wildlife Society.  相似文献   

14.
Most studies of plains zebra (Equus burchellii) have focused on population ecology and have not included long-term observations of identified individuals. Over a 5-year period, we studied the crepuscular activities of 13 individual zebras within a focal group held within a managed game reserve. We also examined individual residency within the group by recording births, mortalities and longevity of group membership by adults. Residency of individuals living in other groups on the reserve was similarly monitored to examine variability in social structure within this closed population over an extended period of time. Stable, female groups were the mainstay of group sociality with male mean residency at 31.6 months being variable in length or even absent. Social interactions across all categories of zebras were free from aggression. Despite an absence of non-human predators, the proportion of dusk time budget allocated to vigilance was high, at 41% for males during periods when they accompanied stable female groups and 12% for females during these same periods. Female vigilance increased significantly to 19% when males were not resident. Females spent 70% of the time grazing and males just 36%. Due to its long-term nature, we concluded this study established a base line for plains zebra activity that could assist in understanding the factors that influence the successful management and conservation of healthy populations.  相似文献   

15.
Africa's large predator guild competes for a limited food resource base. To minimize the degree of competition, we hypothesized that the two largest members of this guild and its fiercest competitors, the lion and the spotted hyaena, would partition their activity patterns to avoid interacting. We used 96‐h continuous follows of focal animal(s) to determine when the six radio‐collared lions and eight radio‐collared spotted hyaenas, reintroduced into Addo Elephant National Park in 2003/2004, were active using a binomial measure of activity which was defined as movements >100 m during each hourly period. Contrary to our predictions, lions and hyaenas did not partition their activity times, probably because of their current low population densities. Both species exhibited a crepuscular activity pattern although hyaenas were far less active during daylight. A sub‐adult lioness minimized competitive interactions by becoming diurnal. This is likely to be a common strategy for lions that have been expelled from their natal pride to become nomadic, as it allows them to minimize kleptoparasitic and agonistic interactions from competitively dominant conspecifics and competitors. The increase in testosterone that occurs in males upon reaching sexual maturity, darkens their pelage and causes them to be more directly impacted by the heat, and thereby affords females an opportunity to escape from males during hot temperatures. Similarly, the longer pelage of young hyaenas restricts their activity to the cooler night‐time.  相似文献   

16.
Mauka-to-makai (mountain to sea in the Hawaiian language) hydrologic connectivity – commonly referred to as ridge-to-reef – directly affects biogeochemical processes and socioecological functions across terrestrial, freshwater, and marine systems. The supply of freshwater to estuarine and nearshore environments in a ridge-to-reef system supports the food, water, and habitats utilized by marine fauna. In addition, the ecosystem services derived from this land-to-sea connectivity support social and cultural practices (hereafter referred to as socio-cultural) including fishing, aquaculture, wetland agriculture, religious ceremonies, and recreational activities. To effectively guide island resource management, a better understanding of the linkages from ridge-to-reef across natural and social usages is critical, particularly in the context of climate change, with anticipated increasing temperature and shifting precipitation patterns. The objective of this study was to identify spatial linkages that promote multiple and diverse uses, following the ridge-to-reef concept, at an island-wide scale to identify regions of high conservation importance for aquatic resources. We selected the Island of Maui as a study representative of many Pacific islands. Diverse datasets, including agricultural lands within watersheds, wetland locations, presence of stream species, indicators of freshwater input from streams, coral cover, nearshore fish biomass, socio-cultural data such as fishpond locations, wetland taro cultivation, beach recreation use, and lastly the dynamically downscaled Coupled Model Intercomparison Project Phase (CMIP5) future climate projections scenarios (Representative Concentration Pathway (RCP) 4.5 & 8.5) were used to examine the spatial linkages through hydrological connectivity from land to the sea. Zonation spatial planning software was used to prioritize areas of high management and conservation value and to help inform aquatic resources management. The resulting prioritized areas included many minimally disturbed watersheds in east Maui and western nearshore and coastal zones that are adjacent to diverse coral reefs. These results are driven by the importance of fish biomass and coral reef distribution as well as traditional wetland taro cultivation and coastal access points for recreation. These results underline the importance of examining ridge-to-reef systems for aquatic resource management and including important social and cultural values in resource management upon planning adaptation strategies for climate change. Improving our understanding of diverse natural and socio-cultural influences on habitat conditions and their values in these areas provides an opportunity to strategically plan future management and conservation actions.  相似文献   

17.
The effects of size and age on reproductive dynamics of common coral trout Plectropomus leopardus populations were compared between coral reefs open or closed (no‐take marine reserves) to fishing and among four geographic regions of the Great Barrier Reef (GBR), Australia. The specific reproductive metrics investigated were the sex ratio, the proportion of vitellogenic females and the spawning fraction of local populations. Sex ratios became increasingly male biased with length and age, as expected for a protogyne, but were more male biased in southern regions of the GBR (Mackay and Storm Cay) than in northern regions (Lizard Island and Townsville) across all lengths and ages. The proportion of vitellogenic females also increased with length and age. Female P. leopardus were capable of daily spawning during the spawning season, but on average spawned every 4·3 days. Mature females spawned most frequently on Townsville reserve reefs (every 2·3 days) and Lizard Island fished reefs (every 3·2 days). Females on Mackay reefs open to fishing showed no evidence of spawning over 4 years of sampling, while females on reserve reefs spawned only once every 2–3 months. No effect of length on spawning frequency was detected. Spawning frequency increased with age on Lizard Island fished reefs, declined with age on Storm Cay fished reefs, and declined with age on reserve reefs in all regions. It is hypothesized that the variation in P. leopardus sex ratios and spawning frequency among GBR regions is primarily driven by water temperature, while no‐take management zones influence spawning frequency depending on the region in which the reserve is located. Male bias and lack of spawning activity on southern GBR, where densities of adult P. leopardus are highest, suggest that recruits may be supplied from central or northern GBR. Significant regional variation in reproductive traits suggests that a regional approach to management of P. leopardus is appropriate and highlights the need for considering spatial variation in reproduction where reserves are used as fishery or conservation management tools.  相似文献   

18.
The introduction and eradication of alien invasive plant species potentially alters feeding and spatial ecology of wild primates. We investigated whether the removal of an important dietary resource for wild chacma baboons (Papio hamadryas ursinus), black wattle (Acacia mearnsii), from a nature reserve would result in longer daily path lengths (DPLs) and greater movement toward other resources, specifically alternative black wattle stands outside the reserve, agricultural plots, and sleeping and geophagy sites. We fitted a juvenile male baboon with a self-releasing GPS collar to track the focal troop’s movements on Wildcliff Nature Reserve and adjacent properties, located in the Western Cape, South Africa, from January 25, 2010 to January 18, 2011. During this time, Working for Water, an environmental conservation initiative of the South African Department of Water Affairs, removed black wattle from the baboons’ home range. We estimated monthly home range (5.30–20.58?km2) and DPL (1.7–11.7?km) and quantified the baboons’ use of five dominant vegetation types. Our vegetation use-availability analysis indicated that the troop preferred black wattle, Afromontane forests, and, to a lesser extent, pasture, but used agricultural plots and fynbos less than expected by availability. With increasing black wattle removal in the core area, the troop traveled further toward distant sources of black wattle, using sleeping sites out of their core area to accommodate such long day journeys. A general linear model indicated that movement to black wattle stands, as well as changing sleeping sites, day length, and both spring and winter seasons all significantly increased DPL. We suggest the influence that alien invasive species and their eradication has on ranging behavior should be a consideration in primate conservation and management policies.  相似文献   

19.
Wildlife agencies are generally tasked with managing and conserving species at state and local levels simultaneously. Thus, it is necessary for wildlife agencies to understand basic ecological processes of a given species at multiple scales to aid decision making at commensurately varied spatial and behavioral scales. Mountain lions (Puma concolor) occur throughout California, USA, and are at the center of a variety of management and conservation issues. For example, they are genetically and demographically at risk in 1 region yet apparently stable and negatively affecting endangered species in another. Currently, no formal plan exists for mountain lions in California to deal with these diverse scenarios involving issues of local mountain lion population viability and problems related to predation of endangered species. To facilitate development of a state-wide management and conservation plan, we quantified habitat selection by mountain lions at 2 spatial scales across the range of environmental conditions in which the species is found in California. Our analyses used location data from individuals (n = 263) collared across the state from 2001–2019. At the home range scale, mountain lions selected habitat to prioritize meeting energetic demands. At the within home range scale, mountain lions avoided areas of human activity. Further, our analyses revealed 165,350–170,085 km2, depending on season, of suitable mountain lion habitat in California. Fifty percent of the suitable habitat was on unprotected lands and thus vulnerable to development. These habitat selection models will help in the development of a state-wide conservation and management plan for mountain lions in California by guiding mountain lion population monitoring through time, prioritization of habitat to be conserved for maintaining demographic connectivity and gene flow, and efforts to mediate mountain lion-prey interactions. Our work and application area will help with wildlife policy and management decisions related to depredation problems at the local scale and issues of habitat connectivity at the statewide scale. © 2019 The Wildlife Society.  相似文献   

20.
A wide range of dimorphic species exhibit intraspecific differences in feeding ecology and habitat use; however, studies comparing resource partitioning between males and females and between age groups occur mainly at the community and species level. We here classified the main habitat of black-and-white snub-nosed monkeys (Rhinopithecus bieti) –fir tree crown– into six microhabitats; examined the lichen-load of the microhabitats; and investigated the microhabitat use of age–sex groups within one-male units (OMUs: an adult male, several females, and juveniles) of R. bieti using instantaneous scanning sampling methods to test whether there is resource niche partitioning in social units of this sexually dimorphic primate in a reserve in Yunnan, China. Our results showed that adult females and juveniles often foraged in the outer layer of the fir tree crown, whereas adult males often foraged in the inner layer, closer to the trunk where food abundance was highest. Adult females and juveniles, however, both shifted microhabitat-use patterns to the inner layer of the fir tree crown when the adult male was absent from the tree. We suggested that the preference for and benefit of the central layer of fir tree crown lies in food availability, but that adult male competitively excluded group members. Microhabitat segregation may serve to maximize the fitness of the group members by reducing intragroup competition, while also increasing interindividual distance, thereby reducing the possible effects of scramble competition.  相似文献   

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