Dynamics and Regulation of Red Squirrel (Tamiasciurus Hudsonicus) Populations

Kemp, Gerald A.; Keith, Lloyd B.

doi:10.2307/1933969

Cited by 177 publications

(155 citation statements)

References 19 publications

Supporting

Mentioning

122

Contrasting

Unclassified

Order By: Relevance

“…The key role of ripening seed Nearly 40 years ago Kemp & Keith (1970) found that the reproduction of American red squirrels, and the survival of their young, improved in springs that followed winters of poor crops of spruce cones, and immediately preceding heavy crops in the following winters. Spruce cones are initiated during the previous season's flowering and the squirrels were feeding on the flower buds and developing fruit.…”

Section: An Alternative Explanationmentioning

confidence: 99%

Mast seeding and mammal breeding: Can a bonanza food supply be anticipated?

White¹

2007

New Zealand Journal of Zoology

View full text Add to dashboard Cite

Boutin et al. (2006) claimed that American and Eurasian red squirrels use an unknown environmental cue to anticipate the availability of the abundant food of an autumn seed mast, and produce more young than usual in the previous spring and summer. But these small mammals need increased supplies of protein to produce and support young, therefore they must have had access to some other protein-rich food that was available before the mast was ripe. There are other small mammalian seedeaters that increase their reproductive output ahead of the maturation of a seed mast. It seems likely that, in each case, females are able to produce extra young in advance because they eat the amino acid-rich inflorescences and unripe seeds of the mast and/or larval insects that also increase their numbers in the spring of a mast year by eating the same enriched plant food.

show abstract

Section: An Alternative Explanationmentioning

confidence: 99%

Mast seeding and mammal breeding: Can a bonanza food supply be anticipated?

White¹

2007

New Zealand Journal of Zoology

View full text Add to dashboard Cite

show abstract

“…Significant annual variations in pregnancy rate are common for red squirrels in western North America. The percentage of adult females breeding increased from 67 per cent to 88 per cent over a 1-year period in Alberta (Kemp and Keith, 1971) and decreased from 83 per cent to 32 per cent over a 1-year period in British Columbia (Smith, 1968).…”

Section: Reproduction In the Red Squirrel (Tamiasciurus Hudsonicus) Imentioning

confidence: 97%

“…Information on reproduction of the red squirrel (Tamiasciumrs hudsonicus) can be gleaned from studies in the northeastern United States (Klugh, 1927;Hamilton, 1939;Layne, 1954) and in western Canada (Miller, 1970;Smith, 1968;Kemp and Keith, 1971;Wood, 1967). However, there is a paucity of information on reproduction from the mountainous regions of the western United States.…”

Section: Reproduction In the Red Squirrel (Tamiasciurus Hudsonicus) Imentioning

confidence: 99%

“…Females collected in a definite state of estrus (long, coiled vagina with diameter > 7 millimeterssee Layne, 1954, andMiller, 1970) were considered as breeding as were females containing visibly implanted fetuses. Females collected from June to September showing placental scars or longitudinal striations on the uterine wall also were considered as breeding (Kemp and Keith, 1971 ). All other females were considered as nonbreeding.…”

Section: Reproduction In the Red Squirrel (Tamiasciurus Hudsonicus) Imentioning

confidence: 99%

“…Wood (1967) Studies by Soper (1942), Hatt (1943), Smith ( 1968, and Kemp and Keith (1971) indicated that red squirrels ~roduce only one litter per year in western North America. Miller (1970) did record the production of two litters in 1 of the 2 years of his study in British Columbia; however, an unusually mild spring occurred in that year and squirrels began breeding in February.…”

Section: Reproduction In the Red Squirrel (Tamiasciurus Hudsonicus) Imentioning

confidence: 99%

See 2 more Smart Citations

Reproduction in the Red Squirrel (Tamiasciurus hudsonicus) in Colorado

Dolbeer¹

1973

Journal of Mammalogy

View full text Add to dashboard Cite

Contrasting stress response of male Arctic ground squirrels and red squirrels

Boonstra

McColl

2000

J. Exp. Zool.

View full text Add to dashboard Cite

A hormonal‐challenge protocol was used to compare the stress response of males of Arctic ground squirrels and red squirrels during the breeding season (May). These squirrels live in the same boreal forest of the Yukon, but have very different life histories and utilize the forest in markedly different ways. Red squirrels had levels of total cortisol, maximum corticosteroid‐binding capacity, and free cortisol that were 5, 7, and 2 times, respectively, those of Arctic ground squirrels. Red squirrels were resistant to suppression by an artificial glucocorticoid, dexamethasone (DEX); Arctic ground squirrels were not. Cortisol levels in red squirrels responded slowly but continuously to the ACTH injection; Arctic ground squirrels responded rapidly and then stabilized. Testosterone levels in red squirrels were extremely sensitive to the challenge, being suppressed by both DEX and ACTH; levels in Arctic ground squirrels were resistant to the challenge, being modestly suppressed by DEX and stimulated by ACTH. Energy mobilization, as measured by glucose and free fatty acid responses, was not affected. Red squirrels had four times the levels of white blood cells and higher proportions of lymphocytes and lower proportions of eosinophils than Arctic ground squirrels, indicating that the latter were in worse condition immunologically. Our evidence suggests that the functions associated with the hypothalamic‐pituitary‐adrenal axis are compromised in breeding male Arctic ground squirrels, but not in red squirrels. We propose that in male red squirrels this axis has evolved in the context of a stable social system based on long‐lived animals with individual territories which are needed to deal with unpredictable winter food supplies. In contrast, Arctic ground squirrels escape the rigors of winter by hibernation and this hormonal axis has evolved in short‐lived males in the context of intense intra‐sexual competition in a social system based on female kin groups and regular male dispersal to avoid inbreeding. J. Exp. Zool. 286:390–404, 2000. © 2000 Wiley‐Liss, Inc.

show abstract

Dynamics and Regulation of Red Squirrel (Tamiasciurus Hudsonicus) Populations

Cited by 177 publications

References 19 publications

Mast seeding and mammal breeding: Can a bonanza food supply be anticipated?

Mast seeding and mammal breeding: Can a bonanza food supply be anticipated?

Reproduction in the Red Squirrel (Tamiasciurus hudsonicus) in Colorado

Contrasting stress response of male Arctic ground squirrels and red squirrels

Contact Info

Product

Resources

About