Sexual Segregation Research Articles

Pronounced inter-colony variation in the foraging ecology of Australasian gannets: influence of habitat differences

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 556:261-272 (2016) - DOI: https://doi.org/10.3354/meps11845 Pronounced inter-colony variation in the foraging ecology of Australasian gannets: influence of habitat differences Lauren P. Angel*, Maud Berlincourt, John P. Y. Arnould School of Life and Environmental Sciences (Burwood campus), Deakin University, Geelong, Victoria 3216, Australia *Corresponding author: lauren.angel@deakin.edu.au ABSTRACT: The predictability of prey due to oceanographic features can result in large aggregations of apex predators. Central place foragers, such as seabirds, are limited in their foraging duration and range during the breeding period, which can restrict their ability to reach such locations. Segregation by colony and sex can further restrict foraging range and may have direct implications for the foraging ecology of a species. In parts of its range, the Australasian gannet Morus serrator breeds in colonies of relatively close proximity and has recently been found to display sexual dimorphism. Two neighbouring breeding colonies in Bass Strait that experience divergent environmental conditions were investigated to determine whether these conditions or the sex of the individual are important variables influencing foraging behaviour in this species. GPS tracking and accelerometry were paired with stable isotope analysis to compare differences in foraging effort, habitat use and diet. Birds from Point Danger, a large colony located near a seasonally strong upwelling, travelled considerably further (77%) than birds from Pope’s Eye, a small colony in a nutrient-poor embayment. However, within colonies no sexual differences in foraging effort were found. While the colonies did not overlap in foraging areas, a degree of sexual segregation was apparent within both colonies (Point Danger 46.3% overlap and Pope’s Eye 73.7% overlap in home range). Furthermore, stable isotope analysis indicated birds from each colony fed at different trophic niches. This study reveals differences in habitat use and, consequently, dietary niches between and within neighbouring colonies. KEY WORDS: Foraging ecology · GPS tracking · Accelerometry · Stable isotopes · Sexual‑segregation · Morus serrator Full text in pdf format PreviousNextCite this article as: Angel LP, Berlincourt M, Arnould JPY (2016) Pronounced inter-colony variation in the foraging ecology of Australasian gannets: influence of habitat differences. Mar Ecol Prog Ser 556:261-272. https://doi.org/10.3354/meps11845 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 556. Online publication date: September 08, 2016 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2016 Inter-Research.

The spatial segregation patterns of sharks from Western Australia

The extent to which sharks segregate by size and sex determines the population structure and the scale at which populations should be managed. We summarized 20 years of fisheries-dependent and independent sampling to define the spatial patterns of size and sexual segregation for sharks in Western Australia. Carcharhinus obscurus and C. plumbeus showed a large-scale (more than 1000 km) latitudinal gradient in size. Large individuals occurred predominantly in the northwest and north whereas smaller individuals occurred predominantly in the southwest and south. Mustelus antarcticus and Furgaleus macki showed strong sexual segregation at very large scales. Females occurred predominantly in the west and southwest whereas the proportion of males in catches substantially increased in the southeast. The populations of other shark species did not show sex and size segregation patterns at very large scales; most species, however, showed varying degrees of segregation when data were analysed at a smaller scale. These findings highlight the importance of matching the scale of observation to the scale of the phenomenon observed. As many shark species are highly mobile, if sampling is opportunistic and constrained both temporally and spatially, the observed segregation patterns may not be representative of those at the population level, leading to inaccurate scientific advice.

Sexual segregation in habitat use is smaller than expected in a highly dimorphic marine predator, the southern sea lion

Sexual segregation in habitat use is widely reported in many taxa and can profoundly influence the distribution and behaviour of animals. However, our knowledge of the mechanisms driving sexual segregation is still in its infancy (particularly in marine taxa) and the influence of extrinsic factors in mediating the expression of sex differences in foraging behaviour is underdeveloped. Here, we combine data from biologging tags, with stable isotope analysis of vibrissae, to assess sexual segregation in southern sea lions (SSL) (Otaria flavescens) breeding at the Falkland Islands in the South Atlantic. We found evidence to support segregation, most notably in δ13C and δ15N values. However, in spite of extreme sexual size dimorphism and differing constraints related to female-only parental care, adult male and adult female SSL overlapped considerably in isotopic niches and foraging area, and shared similar foraging trip characteristics (such as distance and duration). This is in contrast to SSL breeding in Argentina, where prior studies report sexual differences in foraging locations and foraging trip characteristics. We posit that sexual segregation in SSL is influenced by habitat availability (defined here as the width of the Patagonian Shelf) and individual foraging preferences, rather than commonly invoked individual-based limiting factors per se.

Proximate drivers of spatial segregation in non-breeding albatrosses.

Many animals partition resources to avoid competition, and in colonially-breeding species this often leads to divergent space or habitat use. During the non-breeding season, foraging constraints are relaxed, yet the patterns and drivers of segregation both between and within populations are poorly understood. We modelled habitat preference to examine how extrinsic (habitat availability and intra-specific competition) and intrinsic factors (population, sex and breeding outcome) influence the distributions of non-breeding grey-headed albatrosses Thalassarche chrysostoma tracked from two major populations, South Georgia (Atlantic Ocean) and the Prince Edward Islands (Indian Ocean). Spatial segregation was greater than expected, reflecting distinct seasonal differences in habitat selection and accessibility, and avoidance of intra-specific competition with local breeders. Previously failed birds segregated spatially from successful birds during summer, when they used less productive waters, suggesting a link between breeding outcome and subsequent habitat selection. In contrast, we found weak evidence of sexual segregation, which did not reflect a difference in habitat use. Our results indicate that the large-scale spatial structuring of albatross distributions results from interactions between extrinsic and intrinsic factors, with important implications for population dynamics. As habitat preferences differed substantially between colonies, populations should be considered independently when identifying critical areas for protection.

Aproximación preliminar a la estructura de una colonia de Natalus tumidirostris (Natalidae) durante la época de lluvia en la cueva Macaregua, Santander, Colombia

Introduction: We describe the population size and reproductive aspects of a colony of Natalus tumid- irostris during the rainy season of 2013, in the Macaregua cave (6o39’36.2 ‘’ N and 73o0.6’32.3 ‘’ W), Curiti, Santander, Colombia. Objective: Estimate the sex ratio, age categories, the reproductive status and population size of a colony of N. tumidirostris in this cave. Materials and methods: The capture of individuals was performed with a handmade harp trap, a modi ed mist net and manual capture. Results: We capture a total of 274 individuals of which were 14 recaptures. The sex ratio during the samplings was 7: 1 (June), 1: 1 (August) and 3: 1 (September). The structure of the colony was a form of inverted pyramid, and reports the presence of a nursery in April. As for the reproductive status of females, some were inactive (42%) and another 58% were preparing for reproductive events (proestrus). No reproductive activity was observed in males. The colony size varies in a range of 1941-3279 individuals. Conclusion: For the months of study no sexual segregation occurs, although there were variations in the sex ratio. The presence of a nursery and the description of the reproductive status of females indicate that the breeding season for this species occurs in the rst months of the year, between January and February. The inverted pyramid may indicate a decline in population size.

Sex-specific foraging habits and roost characteristics ofNycticeius humeralisin north-central Arkansas

Sexual segregation is common in polygynous mammals, particularly in wild ungulates, but is less known in bats of North America. Yet, the declining bat populations caused by white-nose syndrome, wind energy facilities, and habitat loss throughout eastern North America require habitat management, which may be sex specific. We thus determined sex-specific roosting and foraging habits of evening bats ( Nycticeius humeralis ) in north-central Arkansas. During the summers of 2013 and 2014, we equipped 70 individuals with radiotransmitters to track their foraging movements and identify their roosts that we characterized with 3 tree-level and 7 plot-level variables. We found that evening bat males and females segregate spatially with females foraging over a larger area than males. Females’ roosts were also higher in elevation. Although the roost itself had similar characteristics between sexes, its surrounding habitat was characterized by less canopy cover and a smaller basal area for females. Our results support sex-specific habits and sexual segregation in a forest-dwelling bat, which highlights the importance of sex-specific studies to inform management decisions that would benefit both sexes, including females for which parental investment is higher.

Biological data from sharks landed within the United Arab Emirates artisanal fishery

Landing site and market surveys of sharks landed along the Arabian Gulf coast of the United Arab Emirates were undertaken between October 2010 and September 2012 to obtain biological data from this artisanal fishery. Data were collected on the size and sex of 12 482 individuals representing 30 species. Maximum sizes of Carcharhinus sorrah, C. amblyrhynchoides and Hemipristis elongata were extended by at least 300 mm total length (TL) compared with published global maxima. The size at 50% maturity was determined for males of five species and this indicated that the males of smaller shark species (<1 000 mm maximum TL) in the fishery were largely mature. For many species, including Loxodon macrorhinus and Mustelus mosis, overall sex ratios were male-biased, indicating that sexual segregation is likely in those species. Furthermore, sex ratios for several species, such as Rhizoprionodon acutus, showed differences across seasons. Overall, the landings contained a high proportion of juveniles, causing concerns about the sustainability of this fishery. Biological parameters of a number of species differed from those recorded earlier for the region, demonstrating a need for additional local data collection to support the development of management measures.

Essential pelagic habitat of juvenile blue shark (Prionace glauca) inferred from telemetry data

Knowledge on the distribution and habitat use of species is an important precondition for their appropriate management and conservation. This is particularly challenging for highly mobile marine predators such as blue shark that migrate between dynamic and transient oceanic habitats. In addition, blue shark populations have complex spatial structures due to age and sexual segregation, and accurately identifying oceanic nursery habitat is vital to ensure population growth via survival of juveniles. In this study, long-term satellite telemetry data (up to 950 d) was used to estimate the broad-scale habitat utilization of juvenile blue shark and predict their distribution in the North Atlantic. Habitat utilization models were fitted separately for three juvenile life stages that recruit to the pelagic longline fishery (small juvenile males and females, large juvenile and sub-adult females and large juvenile males), and subsequently validated using fisheries data. The models demonstrated that the patterns of spatiotemporal distribution and segregation are shaped to a large extent by differential habitat preferences, notably for distinct ranges of sea surface temperature. For the first time, this modeling approach provides a unifying framework to understand the essential pelagic habitat and dynamic spatial structuring of blue shark at the scale of an entire ocean basin. It represents an important contribution to our understanding of the spatial ecology of pelagic sharks by presenting novel clues to their behavioral strategies in exploiting the most productive oceanic habitats, and offers a promising tool for their management in the face of current intensive shark exploitation.

From battling adult authority to battling the opposite sex: Little Lulu as gag panel and comic book

When iconic comics character Little Lulu moved from the Saturday Evening Post, where she had resided since the 1930s, to comic books during the 1950s, her character underwent numerous transformations. One compelling but formerly overlooked change is the nature of Lulu’s rebellion. In the single-panel gag comics, the young girl was overwhelmingly targeting adults with her antics. Meanwhile, in the comic books, her sworn enemy is the gang of neighbourhood boys. This modification from intergenerational conflict in the pre-war era to intragenerational ones during the post-war period forms a compelling and previously unexplored facet to the literary, artistic and cultural alterations to this character that took place across different print formats. At the same time, the shift from plots that pitted children against adults in the 1930s to ones that pitted girls against boys in the 1950s reflects larger shifts in American culture regarding the gendering of children and the sexual segregation of childhood. This essay argues that this new focus did far more than merely permit Marge’s Little Lulu to tell different stories; it radically altered the aim and intent of Buell’s original character along with the commentary on gender, childhood and US culture that it offered.

Persistent organic pollutants in blood samples of Southern Giant Petrels (Macronectes giganteus) from the South Shetland Islands, Antarctica

Seabirds play an important role as top consumers in the food web and can be used as biomonitors of exposure to pollutants. Contamination studies involving non-destructive sampling methods are of considerable importance, allowing better evaluation of the levels of pollutants and their toxic effects. In the present study, organohalogen contaminants were analyzed in 113 blood samples from Southern Giant Petrel (Macronectes giganteus) adults and chicks collected in the austral summer of 2011/2012 and 2012/2013 from colonies on Elephant and Livingston Islands, South Shetland, Antarctica. Polychlorinated biphenyls (PCBs), hexachlorobenzene (HCB), pentachlorobenzene (PeCB), mirex, dichlorodiphenyltrichloroetane and derivatives (DDTs) and chlordanes were detected in all birds, whereas polybrominated diphenyl ethers (PBDEs) were not detected in any blood samples. No significant differences were found in organochlorine levels between sampling events. Adults exhibited significantly higher levels than chicks, except for PeCB. PCBs, HCB, mirex and DDTs were statistically similar in males and females from Elephant Island. Females on Livingston Island exhibited higher HCB values than males, but no sex differences were found regarding other organochlorines. The similarity in organochlorine levels between sexes in birds with very marked sexual segregation in feeding habits during the breeding season may indicate that significant amounts of contaminants are acquired during migration to lower latitudes, when the diets of males and females are similar. Birds sampled on Livingston Island exhibited significantly lower levels of PCBs, HCB, DDTs, mirex and chlordanes in comparison to those on Elephant Island, which could be the result of distinct foraging patterns between the two colonies. Organochlorine levels were similar between years in birds captured in two consecutive breeding seasons. Blood samples from Southern Giant Petrels adults and chicks proved to be useful for the comparison of intraspecific contamination levels and appear to be adequate for the long-term assessment of organohalogen contaminants in antarctic top predators.Organochlorine contaminants in blood samples of Southern Giant Petrels reflected intra-specific differences and suggested distinct foraging patterns between colonies.

Genetic population structure and relatedness in the narrow-striped mongoose (Mungotictis decemlineata), a social Malagasy carnivore with sexual segregation.

Information on the genetic structure of animal populations can allow inferences about mechanisms shaping their social organization, dispersal, and mating system. The mongooses (Herpestidae) include some of the best‐studied mammalian systems in this respect, but much less is known about their closest relatives, the Malagasy carnivores (Eupleridae), even though some of them exhibit unusual association patterns. We investigated the genetic structure of the Malagasy narrow‐striped mongoose (Mungotictis decemlineata), a small forest‐dwelling gregarious carnivore exhibiting sexual segregation. Based on mtDNA and microsatellite analyses, we determined population‐wide haplotype structure and sex‐specific and within‐group relatedness. Furthermore, we analyzed parentage and sibship relationships and the level of reproductive skew. We found a matrilinear population structure, with several neighboring female units sharing identical haplotypes. Within‐group female relatedness was significantly higher than expected by chance in the majority of units. Haplotype diversity of males was significantly higher than in females, indicating male‐biased dispersal. Relatedness within the majority of male associations did not differ from random, not proving any kin‐directed benefits of male sociality in this case. We found indications for a mildly promiscuous mating system without monopolization of females by males, and low levels of reproductive skew in both sexes based on parentages of emergent young. Low relatedness within breeding pairs confirmed immigration by males and suggested similarities with patterns in social mongooses, providing a starting point for further investigations of mate choice and female control of reproduction and the connected behavioral mechanisms. Our study contributes to the understanding of the determinants of male sociality in carnivores as well as the mechanisms of female competition in species with small social units.

Factors of Successful Women Leadership in Saudi Arabia

&lt;p&gt;Saudi woman encounters many shapes of sexual segregation that stand as an obstacle against her option to occupy a frontline leadership position. There are misconceptions in our society that women are not even suitable for leadership. This paper aims to highlight the factors promoting success in leading organizations in general and the success of women in particular with highlighting the status of Saudi women in these factors. The main hypothesis is “the more the woman has factors of leadership, the more success she may achieve in leading organizations”. A model including the factors promoting successful Saudi Women Leaders is proposed and discussed to ensure accuracy of the above mentioned hypothesis. The findings expect bright future for Saudi women in light of keenness of King Abdullah to support woman to play her role in the society and preserve the rights to demonstrate her success in leadership.&lt;strong&gt;&lt;/strong&gt;&lt;/p&gt;

Gregarious sexual segregation: the unusual social organization of the Malagasy narrow-striped mongoose (Mungotictis decemlineata)

Sex-specific costs and benefits of sociality are rarely evaluated, even though the main fitness determinants differ between the sexes. The Carnivora include some of the few mammalian species in which the sexes differ in social organization, providing an opportunity to study male and female sociality separately. Anecdotal reports indicated that Malagasy narrow-striped mongooses (Mungotictis decemlineata) appear to have unusual and flexible association patterns. We therefore conducted a 3-year field study in Western Madagascar to delineate the social organization of this forest-dwelling species and to obtain insights into sex-specific determinants of sociality. We conducted systematic radio tracking on 40 adult individuals (20 males, 20 females) and collected additional data during regular censuses and behavioral observations. We found males and females to live in small, same-sex social units. Males formed stable associations of up to four adult individuals, except for the short annual mating season, when they roamed by themselves. Male home ranges exhibited high mutual overlap and encompassed those of up to four female social unit ranges. Female social units were on average composed of two adult females, one juvenile, and one infant offspring of the dominant female and occupied exclusive territories. Female units were stable year-round and their size was unrelated to home range size, but home range sizes were significantly larger during the dry season. Our analyses indicate that both male and female associations are likely stabilized by antipredator benefits, with females accruing additional benefits from joint resource defense. Males trade off the safety in associations for temporary reproductive opportunities. Thus, antipredator benefits appear to favor group living in both sexes, but sex-specific reproductive fitness limiting factors affect the stability of such units differently. This study presents new detailed results on the sex-specific social organization of a previously unstudied endemic Malagasy carnivore, the narrow-striped mongoose. We relate our findings to important hypotheses of sociobiological theory. In particular, we evaluate the results in comparison to the closest related taxonomic group, the mongooses (Herpestidae), in which long-term studies have contributed substantially to the recent development of theories. Thus, this study on a representative of a largely unknown group of carnivores can contribute to revealing evolutionary transitions in carnivore sociality as well as insights into the mechanisms driving mammalian social evolution in general.

Konstruksi perempuan dan gender dalam gerakan Tarbiyah di kampus-kampus universitas negeri di Surabaya: sebuah modalitas pembangunan karakter bangsa

The Tarbiyah (education) movement in Indonesia today is the best known and has the largest number of members amongst groups in the Dakwah (proselytising) movement that mostly work in Indonesian campuses. However, in contrast to other Islamic revivalist organizations, the Tarbiyah movement, is reformist, and relies heavily on modern interpretations of Islam concerned with democracy, civil society, human rights and equality of women, although these values are understood differently from common Western notions. The group has many female activists but unfortunately until today there has never been any study looking at the ways women has involved in this Tarbiyah movement. This paper aims to explore the numerous and varieties of women‟s activities in this movement, especially in relation the ways women see their rights, roles and sexual identities within their notion of piety. Female and male activists of Tarbiyah movement in Airlangga University (UNAIR), Surabaya State University (UNESA) and Institute of Technology Surabaya (ITS) are respondents in this research. Participation observation and in-depth interviews will used as techniques of data collection. Some finding shows that the Tarbiyah movement‟s espousal of women‟s and gender issues in an Islamic setting complicates even more the dissemination of such issues to the Indonesian public. One important finding indicates that the Tarbiyah conceives that male and female are segregated in nature (biological construction) yet in that segregation lies irreplaceable equality in any sphere and any value. Although many female members of the Tarbiyah movement claim to reject feminism, in particular they reject liberation of women‟s (and men‟s) sexuality, as it is believed to be of Western origin, in fact they subscribe to concepts of sexual equality while maintaining sexual segregation. The rise of the Dakwah movement and its various groups has raised concern in Indonesian society that such groups may pose a threat to civil Islam. However, to see all groups in the Dakwah movement as militant, radical or even fundamentalist is wrong, the complexity of Islamic movements requires careful examination as within these movements groups are fragmented in terms of their interpretations of Islam and its application. Teaching of this Dakwah movement can also be an alternative to national character building as its teachings and morale are in accordance to the values of Indonesian national characters such as honesty, religiousness and others.

Reproductive parameters of the Pacific angel shark Squatina californica (Selachii: Squatinidae).

Reproductive characteristics of the Pacific angel shark, Squatina californica, were evaluated from 420 specimens obtained from the artisanal fishery in La Paz Bay, Gulf of California, Mexico. Females (99 cm, 6000 g) were larger than males (95 cm, 5000 g) in terms of both total length (L(T)) and body mass (M(T)). The overall sex ratio was significantly different from the expected 1:1, suggesting sexual segregation of mature individuals in La Paz Bay. Males had developed reproductive organs and calcified claspers from 72 cm L(T); the median size at maturity (LT50 ) was 75.6 cm. In females, only the left ovary was functional and mature ovarian follicles were present from 77 cm L(T); the estimated LT50 was 77.7 cm. For the 10 gravid females sampled, uterine fecundity was between two and 10 embryos. Mature, non-gravid females with small and large ovarian follicles appeared simultaneously with gravid females with follicles that did not exceed 1.9 cm diameter.

Female dietary bias towards large migratory moths in the European free-tailed bat (Tadarida teniotis).

In bats, sexual segregation has been described in relation to differential use of roosting and foraging habitats. It is possible that variation may also exist between genders in the use of different prey types. However, until recently this idea was difficult to test owing to poorly resolved taxonomy of dietary studies. Here, we use high-throughput sequencing to describe gender-related variation in diet composition of the European free-tailed bat (Tadarida teniotis), while controlling for effects of age and season. We analysed guano pellets collected from 143 individuals mist-netted from April to October 2012 and 2013, in northeast Portugal. Moths (Lepidoptera; mainly Noctuidae and Geometridae) were by far the most frequently recorded prey, occurring in nearly all samples and accounting for 96 out of 115 prey taxa. There were significant dietary differences between males and females, irrespective of age and season. Compared to males, females tended to consume larger moths and more moths of migratory behaviour (e.g.Autographa gamma). Our study provides the first example of gender-related dietary variation in bats, illustrating the value of novel molecular tools for revealing intraspecific variation in food resource use in bats and other insectivores.

Cold Tolerance and Sex-Dependent Hypothermia May Explain Winter Sexual Segregation in a Farmland Bird.

Migration is an important event in the life cycle of many organisms, but considerable intraspecific variation may occur in its timing and/or destination, resulting in sexual segregation during wintering periods. In this study, we tested the body size hypothesis, or cold tolerance hypothesis, which predicts that body size dimorphism modulates metabolic costs associated with cold climate. Using the Eurasian skylark, we first investigated whether this species showed sexual differential migration. Then we explored the body size hypothesis by experimentally testing the effect of low ambient temperature (Ta) on both metabolic rate (MR) and body temperature (Tb). We tested for sex-related differences in metabolism and in energy-saving mechanism (hypothermia). We found clear differential migration by sex in skylark wintering populations, with a male-biased sex ratio decreasing toward southern latitudes. Measurements on captive birds at 20°, 6°, and -5°C demonstrated a significant increase in MR when Ta decreased, but there is no difference between sexes. While both males and females reduced their Tb overnight, Tb reduction was more pronounced in females exposed to the coldest temperature treatment. In addition, we found that individuals with the most reduced Tb lost less body weight during the night, suggesting that Tb reduction may help minimize energy expenditure when conditions become constraining. Our study suggests that functional mechanisms may be involved in latitudinal segregation between sexes and supports the hypothesis that sex-specific physiological strategies and thermal tolerance may explain segregation between sexes.

Sexual and parent–offspring dietary segregation in a colonial raptor as revealed by stable isotopes

AbstractDiet composition and foraging behaviour may show considerable variation among population groups (such as sex and age classes), with potentially important consequences for population dynamics. Thus, failure to account for intra‐specific differences in trophic ecology can bias our understanding of different aspects of population ecology and limit the implementation of effective management and conservation strategies. Although countless studies have investigated the diet of birds, comparatively few have tried to describe intra‐specific sources of dietary variation. Here, we used stable isotope analysis (SIA) to investigate sex‐ and age‐related dietary segregation in the lesser kestrel Falco naumanni breeding in South Iberia and to discuss potential mechanisms involved in such segregation. Females had a narrower isotopic niche width and significantly more depleted δ13C signatures than males during the courtship period, likely due to a higher consumption of energetically rich mole crickets. Our results suggest that sex‐specific differences in the diet of lesser kestrels do not result from intra‐specific competition and are unlikely to be explained by sexual size dimorphism alone. Instead, the main driving force of observed sexual segregation appears to be the different energetic requirements of males and females before laying, when females need a higher allocation of resources to egg production. δ15N isotopic signatures differed significantly between adults and chicks and niche overlap between these age classes was low. Stable isotopic mixing models showed that, compared to adults, the diet of chicks was less diverse and mainly dominated by grasshoppers. Different resource allocation between chicks and adults might also result from different energy requirements, as rapidly growing chicks require more energy than adults, ultimately leading to a parent–offspring dietary segregation. Finally, overall agreement between pellet analysis and SIA methods highlight the potential of SIA for assessing intra‐specific variation in dietary regimes which is often unfeasible through conventional approaches of diet assessment.

Space Use and Movement Patterns in a Semi-Free-Ranging Herd of European Bison (Bison bonasus).

The successful reintroduction and restocking of the European Bison demands a reliable knowledge of the biology of this species. Yet little is known to date about the European bison, and empirical data remains insufficient to set up a reliable plan ensuring the reintroduction, maintenance and survival of populations in habitats that have been largely modified by human activity. Studies of the ecology, social behaviour and management of bison are therefore crucial to the conservation of this species and its cohabitation with humans. To meet these challenges, we focused on movement patterns and space use in a semi-free-ranging herd of European bison living in the Réserve Biologique des Monts-d’Azur (France). Bison spend over 80% of their time foraging and resting; foraging mainly occurs around the artificial feeding sites (i.e., hay racks) or in meadows. The time of day and the presence of snow have no influence on the time budget allocated to each activity. Animals, however, spend more time at the food racks in winter. Bison also spend most of their time in small groups of individuals, confirming the occurrence of both fission-fusion dynamics and sexual segregation in this species. Bison seem to follow a Lévy walk pattern of movement, which is probably related to the geographical distribution and size of food patches in the reserve. The conclusions of this study provide a better understanding of the sociality, life habits and habitat use of bison, and also describe how the provision of hay affects all these behaviours. These results could be useful in the development of tools to select the most suitable habitats for the reintroduction, management and conservation of bison populations.

Roads, routes and rams: does sexual segregation contribute to anthropogenic risk in a desert-dwelling ungulate?

Context Little is known about the consequences of sexual segregation (differential use of resources by the sexes outside of the mating season) for the conservation of large mammals. Roadways (i.e. the strip of land over which a road or route passes) are ubiquitous around the world, and are a major cause of wildlife mortality, as well as habitat loss and fragmentation. Many populations of bighorn sheep (Ovis canadensis) occur at low densities and in a metapopulation structure. Roadways could affect movements of males and females differentially, an outcome that has not been considered previously. Aims We investigated the propensity of the sexes to cross a paved two-lane road and a single-lane, maintained dirt route and predicted that adult males, because of their life-history characteristics, would cross those roadways more often than females. Methods We investigated movements of male and female bighorn sheep from 1986 to 1990. We used a fixed-wing aircraft with an H-antenna on each wing strut to locate individuals each week from October 1986 to December 1990. We estimated the degree of overlap among 50% core areas of use by males and females with the utilisation distribution overlap index (UDOI). Key results We relocated male and female bighorn sheep on 948 occasions during sexual aggregation and on 1951 occasions during sexual segregation. More males than females were likely to cross both types of roadways during segregation, and the dirt route during aggregation. Propensity of males and females to cross roadways was strongly influenced by time of year (i.e. whether the period of sexual aggregation or sexual segregation). The lowest overlap in 50% core areas was between females and males during periods of segregation (UDOI = 0.1447). Conclusions More males than females crossed Kelbaker Road and the unnamed dirt route during segregation, as well as the unnamed route during aggregation. Both of those features could affect males more than females, and could result in reductions in the use of habitat or increased mortality of bighorn sheep from vehicle collisions as a result of spatial segregation of the sexes. Implications During environmental review, biologists should consider sexual segregation when assessing potential anthropogenic effects on movements of bighorn sheep. Biologists also should consider sexual segregation and how roadways, even lightly traveled routes, affect movements of male and female ungulates differently before manipulating habitat, translocating animals, or constructing or modifying roadways.