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

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 flexible. Males tended to have much larger home ranges than females and core-areas 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 significantly 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.

[1]  C. P. Morgan.  The ecology and behaviour of female red squirrels (Sciurus vulgaris) during the breeding season in a conifer plantation , 1994 .

[2]  A. Cockburn.  Habitat heterogeneity and dispersal: environmental and genetic patchiness , 1992 .

[3]  H. Andrén,et al.  Habitat selection in the Eurasian red squirrel, Sciurus vulgaris, in relation to forest fragmentation , 1994 .

[4]  L. Wauters,et al.  Lifetime reproductive success and its correlates in female Eurasian red squirrels , 1995 .

[5]  Christopher C. Smith.  THE INDIVISIBLE NICHE OF TAMIASCIURUS: AN EXAMPLE OF NONPARTITIONING OF RESOURCES' , 1981 .

[6]  Stephen Harris,et al.  Home‐range analysis using radio‐tracking data–a review of problems and techniques particularly as applied to the study of mammals , 1990 .

[7]  Erkki Pulliainen,et al.  Chemical composition of Piceaabies and Pinussylvestris seeds under subarctic conditions , 1984 .

[8]  P. Lurz.  Research note. Conifer species mixtures, cone crops and red squirrel conservation , 1998 .

[9]  J. Gurnell,et al.  Squirrel numbers and the abundance of tree seeds , 1983 .

[10]  W. G. Reeder,et al.  POPULATION ECOLOGY OF ALBERTA RED SQUIRRELS , 1978 .

[11]  L. Butler,et al.  Protein precipitation method for the quantitative determination of tannins , 1978 .

[12]  R. Koford.  Mating System of a Territorial Tree Squirrel (Tamiasciurus douglasii) in California , 1982 .

[13]  Peter W. W. Lurz,et al.  The ecology of squirrels in spruce dominated plantations: implications for forest management , 1995 .

[14]  L. Wauters,et al.  Effects of temporal and spatial variation in habitat quality on red squirrel dispersal behaviour , 1997, Animal Behaviour.

[15]  J. Layne.  The Biology of the Red Squirrel, Tamiasciurus hudsonicus loquax (Bangs), in Central New York , 1954 .

[16]  M. Gadgil.  Dispersal: Population Consequences and Evolution , 1971 .

[17]  G. Kemp,et al.  Dynamics and Regulation of Red Squirrel (Tamiasciurus Hudsonicus) Populations , 1970 .

[18]  H. Andrén,et al.  Population fluctuations and habitat selection in the Eurasian red squirrel Sciurus vulgaris , 1992 .

[19]  J. Gurnell.  Home range, territoriality, caching behaviour and food supply of the red squirrel (Tamiasciurus hudsonicus fremonti) in a subalpine lodgepole pine forest , 1984, Animal Behaviour.

[20]  K. Larsen,et al.  Movements, survival, and settlement of red squirrel (Tamiasciurus hudsonicus) offspring , 1994 .

[21]  I. J. Patterson,et al.  Numbers, breeding performance, and diet of the sparrowhawk Accipiter nisus and merlin Falco columbarius in relation to cone crops and seed-eating finches , 1995 .

[22]  L. Wauters,et al.  Space use and dispersal of red squirrels in fragmented habitats , 1994 .

[23]  Nicholas J. Aebischer,et al.  Compositional Analysis of Habitat Use From Animal Radio-Tracking Data , 1993 .

[24]  L. Wauters,et al.  Spacing behaviour of red squirrels, Sciurus vulgaris: variation between habitats and the sexes , 1992, Animal Behaviour.

[25]  Christopher C. Smith.  The Adaptive Nature of Social Organization in the Genus of Three Squirrels Tamiasciurus , 1968 .

[26]  Christopher C. Smith,et al.  Food Preferences of Squirrels , 1972 .

[27]  R. Ims.  Responses in spatial organization and behaviour to manipulations of the food resource in the vole Clethrionomys rufocanus , 1987 .

[28]  Michael D. Samuel,et al.  Identifying areas of concentrated use within the home range , 1985 .

[29]  L. Lens,et al.  EFFECTS OF FOOD AVAILABILITY AND DENSITY ON RED SQUIRREL (SCIURUS VULGARIS) REPRODUCTION , 1995 .

[30]  R. Ostfeld.  Limiting Resources and Territoriality in Microtine Rodents , 1985, The American Naturalist.

[31]  L. Wauters,et al.  Factors affecting male mating success in red squirrels (Sciurus vulgaris) , 1990 .

[32]  B. A. C. Don.  Home range characteristics and correlates in tree squirrels , 1983 .

[33]  L. Lens,et al.  Variation in territory fidelity and territory shifts among red squirrel, Sciurus vulgaris, females , 1995, Animal Behaviour.