Foraging behaviour at multiple temporal scales in a wild alpine equid

Abstract

Forage abundance, forage quality, and social factors are key elements of the foraging ecology of wild herbivores. For non-ruminant equids, forage-limited environments are likely to impose severe constraints on their foraging behaviour. We used a multi-scale approach to study foraging behaviour in kiang (Equus kiang), a wild equid inhabiting the high-altitude rangelands of the Tibetan Plateau. Using behavioural observations and vegetation sampling, we first assessed how patterns of plant abundance and quality affected (i) the instantaneous forage intake rate (fine scale) and (ii) the proportion of time spent foraging (coarse scale) across seasons. We also tested whether foraging behaviour differed among group types, between sex in adults, and between females of different reproductive status. At a fine scale, intake rate increased linearly with bite size and increased following a type II curvilinear function with biomass on feeding sites. Forage intake rate also increased linearly with plant quality. Male and female kiangs had similar intake rates. Likewise, gravid and lactating females had similar intake rates as barren and non-lactating females. At a coarse scale, kiangs spent longer time feeding in mesic than in xeric habitats, and spent more time feeding in early summer and fall than in late summer. Groups of adults with foals spent less time feeding than male groups and groups of adults without foals. Our findings suggest that kiangs use flexible foraging behaviours in relation to seasonal variations of vegetation quality and abundance, a likely outcome of the extreme seasonal conditions encountered on the Tibetan Plateau.

Field measurements give biased estimates of functional response parameters, but help explain foraging distributions

“…Gill, Sutherland & Norris ; Lourenço et al . ; St‐Louis & Cote ; Duijns & Piersma ). If birds distribute themselves ‘ideal’ and ‘free’ (Fretwell & Lucas ), there will be more birds at higher prey densities.…”

“…These measurements can be fitted to Holling's disc equations (e.g. Gill, Sutherland & Norris 2001;Lourenc ßo et al 2010;St-Louis & Cote 2012;Duijns & Piersma 2014). If birds distribute themselves 'ideal' and 'free' (Fretwell & Lucas 1970), there will be more birds at higher prey densities.…”

Joint effects of weather and interspecific competition on foraging behavior and survival of a mountain herbivore

“…Low rainfall and high temperatures would limit the nutrient supply to plants and, in turn, their digestible protein content, reducing bite rate through a greater handling (chewing) time (e.g., Shipley and Spalinger 1992; Wilmshurst et al. 1999; St. Louis and Côté 2012).…”

Locomotor activity patterns of takin (Budorcas taxicolor) in a temperate mountain region

“…The foraging movement of alpine ungulates is usually influenced by plant biomass in different seasons [ 50 ]. In spring, the microenvironment temperature of the takin habitat increased quickly ( Fig 4 ) and their effect estimate β on movement rates was also maximum ( Table 1 ).…”