Intensity of space use reveals conditional sex‐specific effects of prey and conspecific density on home range size

Abstract

Home range (HR) size variation is often linked to resource abundance, with sex differences expected to relate to sex‐specific fitness consequences. However, studies generally fail to disentangle the effects of the two main drivers of HR size variation, food and conspecific density, and rarely consider how their relative influence change over spatiotemporal scales. We used location data from 77 Eurasian lynx (Lynx lynx) from a 16‐year Scandinavian study to examine HR sizes variation relative to prey and conspecific density at different spatiotemporal scales. By varying the isopleth parameter (intensity of use) defining the HR, we show that sex‐specific effects were conditional on the spatial scale considered. Males had larger HRs than females in all seasons. Females' total HR size declined as prey and conspecific density increased, whereas males' total HR was only affected by conspecific density. However, as the intensity of use within the HR increased (from 90% to 50% isopleth), the relationship between prey density and area showed opposing patterns for females and males; for females, the prey density effect was reduced, while for males, prey became increasingly important. Thus, prey influenced the size of key regions within male HRs, despite total HR size being independent of prey density. Males reduced their HR size during the mating season, likely to remain close to individual females in estrous. Females reduced their HR size postreproduction probably because of movement constrains imposed by dependent young. Our findings highlight the importance of simultaneously considering resources and intraspecific interactions as HR size determinants. We show that sex‐specific demands influence the importance of prey and conspecific density on space use at different spatiotemporal scales. Thus, unless a gradient of space use intensity is examined, factors not related to total HR size might be disregarded despite their importance in determining size of key regions within the HR.

Diets of denning female Pacific martens vary with the developmental stage of their kits

“…Female martens appear to meet the high energetic demands of reproduction by both selecting more energy-rich habitat patches (old forest) and using larger, more energy-rich, prey consistent with behaviors observed in other species of sexually dimorphic carnivores (Arronsson et al, 2016;Breed et al, 2006). Female martens appear to meet the high energetic demands of reproduction by both selecting more energy-rich habitat patches (old forest) and using larger, more energy-rich, prey consistent with behaviors observed in other species of sexually dimorphic carnivores (Arronsson et al, 2016;Breed et al, 2006).…”

“…Studies of untrapped North American marten populations have primarily identified predation as the major cause of mortality (Bull & Heater, 2001;McCann, Zollner, & Gilbert, 2010); however see Johnson, Fryxell, Thompson, and Baker (2009) on the potential for food to limit juvenile survival. In other sexually dimorphic carnivores, females may either exhibit sex-specific selection for more prey-rich habitat patches, use more energy-rich prey, or both during the period when they rear young (Arronsson et al, 2016;Breed, Bowen, McMillan, & Leonard, 2006). If female martens are similar to other mustelids, they may require more than double the daily energy intake of the larger-bodied males during the denning season (e.g., fisher [Pekania pennanti], Powell, 1993).…”

Variation in home range size of red foxes Vulpes vulpes along a gradient of productivity and human landscape alteration

“…Among carnivores, home range sizes have been found to vary by several orders of magnitude both within and among species [5, 8, 9]. Some of this variation has been attributed to differences in body mass [3, 10], population density [8, 11], prey availability [12, 13], environmental productivity and seasonality [14, 15], and intrinsic factors such as sex [16], reproductive status [17], and territoriality and social structure [18, 19]. …”

“…However, there has been much debate as to the relative importance of these factors in shaping home range size, and often, such mechanisms are examined separately despite their synergistic effects on home range size [16, 20]. Thus, the factors influencing variation in home range size are still not well understood, especially across different scales [4, 21–23].…”

Territoriality ensures paternity in a solitary carnivore mammal

“…In the case of females, food acquisition and defence of offspring have been identified as important drivers of their spatio-temporal distribution 3–5 . Consequently, it is expected that the distribution of females will determine the spacing patterns of males, at least during the mating season 1, 2, 6 .…”