title: Testing five hypotheses of sexual segregation in an arctic ungulate.
abstract: 1. Sexual segregation occurs in most species of sexually dimorphic ungulates. At least five not mutually exclusive hypotheses have been formulated to explain patterns of social, habitat and spatial segregation; the indirect competition hypothesis (H1), the nutritional needs hypothesis (H2), the activity budget hypothesis (H3), the weather sensitivity hypothesis (H4), and the predation risk hypothesis (H5). 2. Each hypothesis has a unique set of predictions with respect to the occurrence of segregation, and how seasonality, density dependence and reproductive status affect sexual segregation. 3. We tested this set of predictions in order to separate the hypotheses H1-H5 for patterns of sexual segregation of the Svalbard reindeer based on 9 years data on seasonal estimates of spatial, habitat and social (i.e. grouping with their own sex) segregation in combination with resource selection functions. 4. Our results do not support that one single mechanism causes segregation. The activity budget hypothesis, the nutritional needs hypothesis and the weather sensitivity hypothesis were all partially supported, while the predation risk hypothesis was discarded for Svalbard reindeer because predators have been absent for at least 5000 years. Several mechanisms are thus interacting to explain the full-year pattern of sexual segregation and the combination of mechanisms varies among species and populations.
authors.affiliation: Centre of Ecological and Evolutionary Synthesis, Department of Biology, University of Oslo, PO Box 1066 Blindern, N-0316 Oslo, Norway.
authors.forename: Leif Egil
authors.initials: LE
authors.lastname: Loe
authors.forename: R Justin
authors.initials: RJ
authors.lastname: Irvine
authors.forename: Christophe
authors.initials: C
authors.lastname: Bonenfant
authors.forename: Audun
authors.initials: A
authors.lastname: Stien
authors.forename: Rolf
authors.initials: R
authors.lastname: Langvatn
authors.forename: Steve D
authors.initials: SD
authors.lastname: Albon
authors.forename: Atle
authors.initials: A
authors.lastname: Mysterud
authors.forename: Nils Chr
authors.initials: NC
authors.lastname: Stenseth
mesh_terms: D000818:Animals; D001110:Arctic Regions; D002980:Climate; D017753:Ecosystem; D004734:Energy Metabolism / Q000502:physiology; D005247:Feeding Behavior; D005260:Female; D008297:Male; D008954:Models, Biological; D009664:Norway; D009751:Nutritional Requirements; D011156:Population Density; D011157:Population Dynamics; D011235:Predatory Behavior; D011237:Predictive Value of Tests; D012053:Reindeer / Q000502:physiology*; D012621:Seasons; D012737:Sex Factors; D012919:Social Behavior