Summary
If food is in short supply, then provision of addition food should increase the density of Douglas squirrels. A squirrel population was supplied with extra food during the summers of 1977 and 1978 and winter of 1978–1979 in coastal coniferous forest at Maple Ridge, British Columbia. Food produced a 5-to 10-fold increase in squirrel density compared with control populations. Control densities generally varied from 3 to 10 squirrels per trapping area with the experimental population increasing to 65 animals during the winter feeding. This irruption was produced by immigration, more reproduction in females, and increased survival. After the food was withdrawn, the population declined to a level comparable with the controls. We conclude that Douglas squirrel populations fluctuate in accordance with the abundance of food. Territorial behavior may space individuals within populations of Tamiasciurus douglasii but to density levels determined by the available food supply.
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References
Adams L (1955) Pine squirrels reduce future crops of ponderosa pine cones. Journal of Forestry 53:35
Banfield AWF (1974) The Mammals of Canada. University of Toronto Press, Toronto. p 438
Bock CE, Lepthien LW (1976) Synchronous eruptions of boreal seedeating birds. American Naturalist 110:559–571
Boonstra R, Krebs CJ (1977) A fencing experiment on a high density population of Microtus townsendii. Canadian Journal of Zoology 55:1166–1175
Boonstra R, Krebs CJ (1978) Pitfall trapping of Microtus townsendii. Journal of Mammalogy 59:136–147
Brink CH, Dean FC (1966) Spruce seed as a food of red squirrels and flying squirrels in interior Alaska. Journal of Wildlife Management 30:503–512
Caughley G (1970) Eruption of ungulate populations, with emphasis on Himalayan thar in New Zealand. Ecology 51:53–72
Cole FR, Batzli GO (1978) Influence of supplemental feeding on a vole population. Journal of Mammalogy 59:809–819
Curry-Lindahl K (1962) The irruption of the Norway lemming in Sweden during 1960. Journal of Mammalogy 43:171–184
Dolbeer RA (1973) Reproduction in the red squirrel (Tamiasciurus hudsonicus) in Colorado. Journal of Mammalogy 54:536–540
Fisch GG, Dimock EJ (1978) Shoot clipping by Douglas squirrels in regenerating Douglas fir. Journal of Wildlife Management 42:415–418
Franklin JF (1964) Douglas squirrels cut Pacific silver fir cones in Washington Cascades. U.S.D.A. Forest Service Research Note PNW-15: Pacific Northwest Forest Range Experimental Station, Portland, Oregon. p 3
Garman EH (1951) Seed production by conifers in the coastal region of British Columbia related to dissemination and regeneration. British Columbia Forest Service, Victoria, B.C. Technical Bulletin No. T 35
Garman EH (1955) Regeneration problems and their silvicultural significance in the coastal forests of British Columbia. British Columbia Forest Service, Victoria, B.C. Technical Bulletin No. T 41
Hilborn R, Redfield JA, Krebs CJ (1976) On the reliability of enumeration for mark and recapture census of voles. Canadian Journal of Zoology 54:1019–1024
Jackson HHT (1921) A recent migration of the gray squirrel in Wisconsin. Journal of Mammalogy 2:113–114
Kemp GA, Keith LB (1970) Dynamics and regulation of red squirrel (Tamiasciurus hudsonicus) populations. Ecology 51:763–779
Krajina VJ (1965) Biogeoclimatic zones and classification of British Columbia. Ecology of Western North America 1:1–17
Krajina VJ (1969) Ecology of forest trees in British Columbia. Ecology of Western North America 2:1–147
Krebs CJ (1966) Demographic changes in fluctuating populations of Microtus californicus. Ecological Monographs 36:239–273
Larson JS (1962) Notes on a recent squirrel emigration in New England. Journal of Mammalogy 43:272–273
McKeever S (1961) Relative populations of small mammals in three forest types of northeastern California. Ecology 42:399–402
McKeever S (1964) Food habits of the pine squirrel in northeastern California. Journal of Wildlife Management 28:402–404
Mrosovsky N (1966) Acceleration of annual hibernating cycle to six weeks in captive dormice. Canadian Journal of Zoology 44:903–911
Nixon CM, McClain MW (1969) Squirrel population decline following a late spring frost. Journal of Wildlife Management 33:353–357
Rusch DA, Reeder WG (1978) Population ecology of Alberta red squirrels. Ecology 59:400–420
Schorger AW (1947) An emigration of squirrels in Wisconsin. Journal of Mammalogy 28:401–403
Seton ET (1929) Lives of game animals. Doubleday and Company, New York 4:14–24
Shaw WT (1936) Moisture and its relation to the cone-storing habit of the western pine squirrel. Journal of Mammalogy 17:337–349
Shellhammer HS (1966) Cone-cutting activities of Douglas squirrels in sequoia groves. Journal of Mammalogy 47:525
Smith CC (1968) The adaptive nature of social organization in the genus of tree squirrels, Tamiasciurus. Ecological Monographs 38:31–63
Smith CC (1970) The coevolution of pine squirrels (Tamiasciurus) and conifers. Ecological Monographs 40:349–371
Smith MC (1968) Red squirrel responses to spruce cone failure in interior Alaska. Journal of Wildlife Management 32:305–317
Sullivan TP, Krebs CJ (1981) An irruption of deer mice after logging of coastal coniferous forest. Canadian Journal of Forest Research 11:586–592
Sullivan TP, Sullivan DS, Krebs CJ (1982) Demographic responses of chipmunk (Eutamias townsendii) populations with supplemental food. Ecology (submitted)
Taitt MJ (1981) The effect of extra food on small rodent populations: II. Deermice (Peromyscus maniculatus). Journal of Animal Ecology 50:111–124
Taitt MJ, Krebs CJ (1981) The effect of extra food on small rodent populations: II. Voles (Microtus townsendii). Journal of Animal Ecology 50:125–137
Thompson DC (1978) Regulation of a northern gray squirrel (Sciurus carolinensis) population. Ecology 59:708–715
Walters J, Soos J (1961) Douglas squirrel damage to Douglas fir. Faculty of Forestry Research Note 31. University of British Columbia, Vancouver p 2
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Sullivan, T.P., Sullivan, D.S. Population dynamics and regulation of the Douglas squirrel (Tamiasciurus douglasii) with supplemental food. Oecologia 53, 264–270 (1982). https://doi.org/10.1007/BF00545675
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DOI: https://doi.org/10.1007/BF00545675