Sexual Segregation

"This study conducted in the high altitude rangelands of Indian Transhimalaya, deals
with basic questions regarding the ecology of an endangered species, the wildsheep
Tibetan argali (Ovis ammon hodgsoni) and applied issues related to its conservation
and potential conflict with the local nomadic pastoralists. The basic questions on
ecology are aimed at delineating the habitat and resource selection processes,
identifying factors causing sexual segregation and efficient surveying and sampling.
The applied aspect focuses on the changing face of pastoralism and the potential
impacts of modernising livestock husbandry on argali.
Overall, the study provides a general framework towards the understanding of
argali-habitat relationships at different spatio-temporal scales. The spatial
determinant associated with altitude in the area, predicts argali habitat and resource
selection in this relatively homogenous landscape. These determine the range of
other topographic variables and forage characteristics selected by argali. The
selection of feeding patches in the selected range of altitude and topography is
mainly characterised by their greenness and the quality of plant groups. Adjusting to
changing forage quality, argali display an opportunistic feeding strategy, selecting
grasses in early spring and switching to forbs later in summer. Nevertheless, the
habitat selection process did not appear to differ among the sexes to drive sexual
segregation. There was, however, strong segregation among the sexes as well as
between lactating and non lactating females. The reasons for segregation appeared to
be predominantly social, but driven ultimately by predation and concomitantly by
resources. The habitat selection information was used to design a stratified random
sampling strategy that led to i) a significant reduction in survey effort in sampling
these sparsely distributed species and ii) reduction in sampling bias.
The applied aspect of the study outlines and evaluates the dramatic changes in
the nomadic pastoralism that have occurred in the past five decades in the study
area. These have led to a loss of pastures (-25 to -33%) of the nomads, consequent
readjustment in traditional patterns of pasture use, intensified grazing pressures (25
to 70%) and rangeland degradation in the area. Such changes may have serious
consequences on the survival of local wildlife, as tested with a study of the effects on
argali of livestock presence and resource exploitation. Hence, a successful
conservation and recovery strategy should focus on: minimising the impacts of
livestock on argali, identifying the factors affecting the persistence of the current
populations, increasing local sub populations of this species to prevent extinction
due to stochastic events, prevent loss of genetic diversity and excessive
fragmentation and thus ensuring gene flow.
Ecological Niche Factor Analyses (ENFA), bias-reduced logistic regression and
Fuzzy correspondence analyses (FCA) were used to answer habitat and resource
selection questions. A sexual segregation and aggregation statistic (SSAS) was used
to estimate the components of sexual segregation and test segregation. SSAS
combined with canonical correspondence analyses (CCA) allowed the estimation of
segregation based on habitat variables. Logistic regression models were formulated
to estimate models on which the stratified random sampling strategy was based. The study also included surveys, interviews and literature reviews to understand
the nomads’ movement and pasture use patterns of their livestock. Kernel density
estimations (KDE) were used to estimate extent of range overlaps between livestock
and argali"

Intraspecific variation can have important knock-on effects on population dynamics and ecosystem
processes. There are good indicators that intraspecific differences may exist in the foraging ecology of kea
parrots (Nestor notabilis). Kea breed in two markedly different habitats (alpine and temperate rainforest), and
have pronounced sexual size dimorphism of their upper bill, which may indicate niche partitioning between
the sexes. Additionally, as a long-lived species, they can potentially acquire a vast amount of information
regarding food sources within their environment, suggesting variation between age classes. We used field
observations and faecal analysis to investigate the foraging ecology of kea. We found evidence of invertebrate
foraging significantly more frequently in temperate rainforest than in alpine regions, where kea foraged more
frequently on fruit. In the alpine habitat, kea fed mainly on fruit during summer and autumn, changing primarily
to leaves during winter and spring and increasing invertebrate consumption in springtime. Although there was
no discernible impact of sex, we found that adult males foraged more on roots and invertebrates than immature
kea, possibly because they were able to exploit a more varied diet through experience. Future research should
investigate the relationship between invertebrate foraging and breeding ecology in kea.

In many mammals, males and females live solitarily or in separate groups outside the breeding season. Sexual segregation is wide-spread in ungulates, but also occurs in whales, seals, monkeys, macropods, elephants, sh and bird species. What causes segregation by sex is still poorly understood, despite intense research done mainly on different ungulate species. In most species studied, males were clearly larger than females. The evolution of sexual dimorphism in body size has largely been attributed to sexual selection and mating strategies. While the consequences of body-size differences on energy requirements and metabolic rates received most attention, studies on consequences of sexual body-size differences on behavior are lacking. This review emphasizes the importance to study a wide range of social mammals with a different or no degree of sexual segregation and sexual dimorphism in body size; something which has not been done and has greatly limited our ability to test alternati...