Home ranges, habitat and body mass: simple correlates of home range size in ungulates

Abstract

The spatial scale of animal space use, e.g. measured as individual home range size, is a key trait with important implications for ecological and evolutionary processes as well as management and conservation of populations and ecosystems. Explaining variation in home range size has therefore received great attention in ecological research. However, few studies have examined multiple hypotheses simultaneously, which is important provided the complex interactions between life history, social system and behaviour. Here, we review previous studies on home range size in ungulates, supplementing with a meta-analysis, to assess how differences in habitat use and species characteristics affect the relationship between body mass and home range size. Habitat type was the main factor explaining interspecific differences in home range size after accounting for species body mass and group size. Species using open habitats had larger home ranges for a given body mass than species using closed habitats, whereas species in open habitats showed a much weaker allometric relationship compared with species living in closed habitats. We found no support for relationships between home range size and species diet or mating system, or any sexual differences. These patterns suggest that the spatial scale of animal movement mainly is a combined effect of body mass, group size and the landscape structure. Accordingly, landscape management must acknowledge the influence of spatial distribution of habitat types on animal behaviour to ensure natural processes affecting demography and viability of ungulate populations.

Keywords: allometry; diet; group size; landscape effects; mating system; space use.

Figure 1.

How interspecific factors are expected to affect home range size and the allometric relationship between body mass and home range size. (a) Because of higher predation risk in open habitats, species living in open habitats will have overall larger home ranges than species in closed habitats. However, the higher movement efficiency between foraging patches with increasing body size will result in a shallower allometric slope between body size and home range size in open compared to closed habitats. (b) Because of the more patchily distribution of browse compared with grass, browsers will have larger home ranges compared with grazers. However, larger bodied browsers have higher energetic demands and will need to include more and larger patches, which will be more dispersed and heterogeneous compared with the spatial distribution of food resources of larger grazers. This will give a steeper allometric slope between body mass and home range size for browsers than for grazers. (c) Females will have smaller home ranges than males owing to more selective foraging in heterogeneous landscapes, and because of movement constraints by calf at heal. However, increasing group size decreases sex difference in home range size (not shown in figure). (d) Owing to costs of defence and loss of mating benefits with increasing area, territorial males should have smaller home ranges than tending males.

Figure 2.

The relationship between home range size (in square kilometres) and body mass (in kilograms) for species belonging to Artiodactyla and Perissodactyla with respect to the dominating habitat the species inhabit (closed, grey/dotted; mixed, light grey/solid; open, dark grey/dashed). Predicted lines accounts for estimate uncertainty and use the mean group size (ln-transformed) across species.