Effects of temporal and spatial variations in food supply on the space and habitat use of red squirrels (Sciurus vulgaris L.)

Abstract

In non-native conifer plantations characterized by strong spatial and temporal variations in the availability of tree seeds in Spadeadam Forest, northern England, the home range and habitat use of red squirrels Sciurus vulgaris was very¯exible. Males tended to have much larger home ranges than females and coreareas of most breeding females seemed mutually exclusive. Adult female red squirrels were found to increase their home range and core-area size in forest patches where food was less abundant. Home-range size was signi®cantly related to home-range quality and the extent of overlap by other females. In contrast with high-quality continuous conifer forests: (1) a considerable proportion of adult males and females at Spadeadam shifted home range, (2) both sexes had much larger home ranges than reported from other habitats in Britain or Belgium. Many ranges were multinuclear, particularly from January onwards, when supplies of seeds become depleted through consumption and seed shed. Squirrels tracked the availability of conifer seeds (lodgepole pine cones throughout the study, Norway spruce cones in spring 1992 and Sitka spruce cones in autumn 1993) and intensively used several non-adjacent activity centres in temporally food-rich patches. Consequently, habitat preference changed markedly with time. The squirrels seemed to maximize nitrogen intake and to avoid the smaller seeds when possible. This resulted in an overall preference for a mixed diet of lodgepole pine and spruce seeds and avoidance of Sitka spruce seeds when Norway spruce seeds were available. These results lend support to the hypothesis of Ostfeld (1985) that when food is sparse and patchily distributed, females should develop intrasexual territoriality, concentrating their activity in food-rich patches, while males should be non-territorial and adapt their space use to the distribution of females.

Within‐sex density dependence and population dynamics of red squirrels Sciurus vulgaris

“…Finally, the animal's relatively large body size, diurnal habits and average lifetime allow detailed analysis of their lifehistory traits and social organization (Wauters & Dhondt 1989, 1992, 1995Lurz et al . 1997Lurz et al . , 2000.…”

Spacing Behavior of a Non‐Larder‐Hoarding Tamiasciurus: A Study of Mearns's Squirrels in Xeric Coniferous Forests

“…Thus, like other rodent species with scramble competition mating systems (Koprowski 2007;Lane et al 2009;Raveh et al 2010;Marmet et al 2012), only those males that can locate estrous females faster than other male competitors should be favored by sexual selection, as female tree squirrels are commonly in estrus for <1 d and likely <8 h (Koprowski 2007). Mearns's squirrels exhibited intra-and intersexual overlap in 95% FK home ranges year round similar to scatter-hoarding rodents (Frank & Heske 1992;Lurz et al 2000;Shier & Randall 2004;Cudworth & Koprowski 2010), including red squirrels in deciduous forests (Layne 1954;Kemp & Keith 1970;Don 1983;Gurnell 1984). Nonetheless, overlap only differed between seasons suggesting that overlap is similar for both sexes within seasons, with lower and higher overlap during non-mating and mating seasons, respectively, between sexes.…”

“…An increase in overlap during mating season between female Mearns's squirrels may be due to habitat heterogeneity with females searching more widely for food, but covering areas of similar size as those traveled during non-mating season. In Eurasian red squirrels and root voles (Microtus oeconomus), higher overlap between females only occurs when food supply declines and consequently energy requirements increase, particularly during mating season (Lurz et al 2000;Hoset et al 2008). Mearns's squirrels also rely on tree cavities for nesting (Ramos-Lara et al 2013), and both sexes were observed frequently inspecting tree cavities which also may have contributed to increased overlap with other conspecifics, particularly breeding females (Peterson & Gauthier 1985;Hanski et al 2000).…”

“…In areas with high variation in food supply, Eurasian red squirrels and Arizona gray squirrels (Sciurus arizonensis) maintain large home ranges year round as a strategy to respond to this variation (Lurz et al 2000;Cudworth & Koprowski 2010). Mearns's squirrels may have adopted a similar strategy, maintaining large home ranges and shifting among food types as available (Gurnell 1987;Fletcher et al 2010), with females increasing overlap during mating season but exhibiting similar home-range sizes year round.…”

Effect of behavioral marginality on survival of an alpine ungulate

“…Space use integrates complex behavioral decisions that include intra-and inter-specific competition (Davis et al 2017); antipredator strategy (Thaker et al 2011, Palmer et al 2017; quality, quantity, and configuration of resources (Lurz et al 2000, Marzluff et al 2004; and social structure (Fortin et al 2009, Lesmerises et al 2018a). Consequently, space use can have important impacts on individual survival or recruitment (Brinkman et al 2004, Lafontaine et al 2017.…”