Seasonal changes in territory use by red squirrels, Tamiasciurus hudsonicus, and responses to food augmentation

2002 ◽  
Vol 80 (11) ◽  
pp. 1957-1965 ◽  
Author(s):  
Kara L Vlasman ◽  
John M Fryxell
Keyword(s):  
Habitat Use ◽  
Food Availability ◽  
Territory Size ◽  
Tamiasciurus Hudsonicus ◽  
Red Squirrel ◽  
Red Squirrels ◽  
Treatment Groups ◽  
Conspecific Density ◽  
Effect Of Food ◽  
Seasonal Influences

Traditionally, the importance of food availability and intruder pressure on habitat use have been investigated through their influences on territory size. Food-augmentation studies are more prevalent; however, they are potentially confounded by the indirect effect of conspecific attraction to local food additions. Frequent ambiguous results may be attributed to the scale of investigation. Furthermore, such investigations have not considered potential seasonal influences. In this study, controlled experimental manipulations of food availability and conspecific density were performed within red squirrel (Tamiasciurus hudsonicus) territories in Algonquin Park, Ontario, to tease apart the relative importance of direct and indirect effects of food augmentation. Effects were investigated at two levels of scale, using territory size and giving-up densities (GUDs) within activity locations as response variables. Augmenting food, with or without simultaneously removing conspecifics, did not influence territory size. However, territory size decreased in control and treatment groups following manipulations, which is suggestive of seasonal influences associated with caching behaviour and midden defence. Despite overwhelming seasonal influences, GUDs were more sensitive to treatments, revealing that competitors had a greater influence on habitat use than the direct effect of food addition. Ambiguous results of previous studies may due to the use of territory-size estimators that are insensitive to responses occurring at smaller scales.

SEASONAL DAMAGE BY INSECTS AND SQUIRRELS TO FEMALE REPRODUCTIVE STRUCTURES OF BLACK SPRUCE, PICEA MARIANA (MILL.) B.S.P.

1988 ◽  
Vol 120 (12) ◽  
pp. 1113-1121 ◽  
Author(s):  
Y.H. Prévost ◽  
J.E. Laing ◽  
V.F. Haavisto
Keyword(s):  
Picea Mariana ◽  
Black Spruce ◽  
Choristoneura Fumiferana ◽  
Tamiasciurus Hudsonicus ◽  
Red Squirrel ◽  
Red Squirrels ◽  
Reproductive Structures ◽  
Cone Axis ◽  
Viable Seeds ◽  
Cone Growth

AbstractThe seasonal damage to female reproductive structures (buds, flowers, and cones) of black spruce, Picea mariana (Mill.) B.S.P., was assessed during 1983 and 1984. Nineteen insects (five Orders) and the red squirrel, Tamiasciurus hudsonicus (Erxleben), were found feeding on these reproductive structures. Collectively, these organisms damaged 88.9 and 53.5% of the cones in 1983 and 1984, respectively. In the 2 years, Lepidoptera damaged 61.8% of the cones in 1983 and 44.4% of the cones in 1984. The spruce budworm, Choristoneura fumiferana (Clem.), and the spruce coneworm, Dioryctria reniculelloides Mut. and Mun., were the most important pests. Cones damaged by Lepidoptera could be classed into three categories: (a) severe, yielding no seeds; (b) moderate, yielding 22.3 seeds per cone; and (c) light, yielding 37.5 seeds per cone. Undamaged cones yielded on average 39.9 seeds per cone. Red squirrels removed 18.8% of the cones in 1983 and none in 1984. The spruce cone axis midge, Dasineura rachiphaga Tripp, and the spruce cone maggot, Lasiomma anthracinum (Czerny), caused minor damage in both years. Feeding by spruce cone axis midge did not reduce cone growth significantly or the number of viable seeds per cone, but feeding by the spruce cone maggot did. During both years new damage by insects to the female reproductive structures of the experimental trees was not observed after mid-July. In 1983 damage by red squirrels occurred from early to late September. In 1984 damage to cones on trees treated with dimethoate was 15.6% compared with 53.5% for untreated trees, without an increase in the number of aborted cones.

Genetic structure of the arboreal squirrels (Glaucomys sabrinus and Tamiasciurus hudsonicus) in the North American Black Hills

2012 ◽  
Vol 90 (9) ◽  
pp. 1191-1200 ◽  
Author(s):  
A.M. Kiesow ◽  
E.M. Monroe ◽  
H.B. Britten
Keyword(s):  
Gene Flow ◽  
Genetic Structure ◽  
Management Practices ◽  
Allelic Diversity ◽  
Black Hills ◽  
Tamiasciurus Hudsonicus ◽  
Glaucomys Sabrinus ◽  
Red Squirrel ◽  
Isolated Populations ◽  
Red Squirrels

We selected two isolated mammalian populations, the Black Hills northern flying squirrel ( Glaucomys sabrinus (Shaw, 1801)) and red squirrel ( Tamiasciurus hudsonicus (Erxleben, 1777)), to elucidate their genetic structure. We trapped both squirrels from 2005 to 2007, in three regions of the Black Hills, differing in geology and vegetation, to collect ear samples for genetic analyses. Microsatellite loci (northern flying (9) and red squirrel (13)) were used to examine genetic structure. Data analyses estimated genetic variability, substructure, and gene flow. Northern flying and red squirrel populations have allelic diversity and observed heterozygosity similar to other isolated populations. Each species shows weak substructure from STRUCTURE and GENELAND analyses, suggesting squirrel movements may be inhibited by topography or unsuitable habitat. Recent gene flow estimates from BAYESASS indicate that both species experience some within population gene flow and red squirrels may be more structured than northern flying squirrels because of lower migration rates. Concordant patterns of genetic structure in northern flying and red squirrels indicate that other species’ movements in the Black Hills may be affected by topography and habitat. Because their habitat is isolated in the Black Hills, management practices and conservation measures are recommended to promote viability and survival of each species.

Body temperature dynamics of the red squirrel (Tamiasciurus hudsonicus): adaptations for energy conservation

1979 ◽  
Vol 57 (7) ◽  
pp. 1349-1354 ◽  
Author(s):  
Ronald W. Pauls
Keyword(s):  
Body Temperature ◽  
Motor Activity ◽  
Energy Conservation ◽  
Outdoor Environment ◽  
Tamiasciurus Hudsonicus ◽  
Rapid Decline ◽  
Red Squirrel ◽  
Red Squirrels ◽  
Air Temperatures ◽  
Temperature Dynamics

Abdominal temperatures (Tb) of two captive female red squirrels (Tamiasciurus hudsonicus) in a natural outdoor environment were monitored by radiotelemetry at air temperatures (Ta) from −33 to 28 °C. Abdominal temperature ranged from 35.9 to 41.4 °C with values usually less than 39 °C when an animal was in the nest and greater than 39 °C when outside. An increase of Tb to about 39 °C usually occurred before an animal left the nest. In the nest Tb was positively correlated with Ta. Outside the nest there was a weak positive correlation at Ta less than 15 °C and a stronger negative correlation at higher Ta. During subnivean activity a rapid decline in Tb usually occurred. It is suggested that in the nest a low Tb is adaptive in that it results in energy conservation while a higher Tb is required outside the nest for rapid and coordinated motor activity.

Behavioural strategies relevant to the energy economy of the red squirrel (Tamiasciurus hudsonicus)

1978 ◽  
Vol 56 (7) ◽  
pp. 1519-1525 ◽  
Author(s):  
Ronald W. Pauls
Keyword(s):  
Locomotor Activity ◽  
Air Temperature ◽  
Activity Patterns ◽  
Tamiasciurus Hudsonicus ◽  
Temperature Cycle ◽  
Red Squirrel ◽  
Red Squirrels ◽  
Time Out ◽  
Energy Economy ◽  
Behavioural Strategies

Amount and intensity of locomotor activity and time out of the nest were measured for a 1-year period on captive red squirrels (Tamiasciurus hudsonicus) under natural conditions. Daily and annual activity patterns and correlations between activity and meteorological variables were examined. A pronounced annual cycle, in phase with the annual temperature cycle, was found in all three aspects of activity. Daily amount of locomotor activity and time out of the nest were closely correlated with mean daily air temperature. Wind, photoperiod, and air temperature during the preceding week showed a weak but significant correlation with activity. Daily patterns of activity varied seasonally from a distinctly bimodal to a unimodal pattern, with a shift in winter to more midday activity. The relevance of these behavioural strategies to the energy economy of the red squirrel is discussed.

scholarly journals Individual variation in phenotypic plasticity of the stress axis

2019 ◽  
Author(s):  
Sarah Guindre-Parker ◽  
Andrew G. Mcadam ◽  
Freya Van Kesteren ◽  
Rupert Palme ◽  
Rudy Boonstra ◽  
...  
Keyword(s):  
Phenotypic Plasticity ◽  
Individual Variation ◽  
Local Density ◽  
Reaction Norm ◽  
Tamiasciurus Hudsonicus ◽  
Stress Axis ◽  
Red Squirrels ◽  
Conspecific Density ◽  
North American Red Squirrels ◽  
Future Work

ABSTRACTPhenotypic plasticity—one individual’s capacity for phenotypic variation under different environments—is critical for organisms facing fluctuating conditions within their lifetime. North American red squirrels (Tamiasciurus hudsonicus) experience drastic among-year fluctuations in conspecific density. This shapes juvenile competition over vacant territories and overwinter survival. To help young cope with competition at high densities, mothers can increase offspring growth rates via a glucocorticoid-mediated maternal effect. However, this effect is only adaptive under high densities, and faster growth often comes at a cost to longevity. While experiments have demonstrated that red squirrels can adjust hormones in response to fluctuating density, the degree to which mothers differ in their ability to regulate glucocorticoids across changing densities remains unknown—little is known about within-individual plasticity in endocrine traits relative to among-individual variation. Findings from our reaction norm approach revealed significant individual variation not only in a female red squirrel’s mean endocrine phenotype, but also in endocrine plasticity in response to changes in local density. Future work on the proximate and ultimate drivers of variation in the plasticity of endocrine traits and maternal effects is needed, particularly in free-living animals experiencing fluctuating environments.

Territory size and ownership in red squirrels: response to removals

1986 ◽  
Vol 64 (5) ◽  
pp. 1144-1147 ◽  
Author(s):  
Karen Price ◽  
K. Broughton ◽  
S. Boutin ◽  
A. R. E. Sinclair
Keyword(s):  
Territory Size ◽  
Red Squirrel ◽  
Red Squirrels

We monitored size and ownership of red squirrel territories in the southwestern Yukon during the summer following a year of abundant cone crop. Territory boundaries were determined by observing marked individuals. Six individuals and two groups (four individuals per group) were removed to test the hypothesis that the position of territory boundaries are determined by intruder pressure. Removed squirrels were replaced by juveniles or by breeding females which had given up their former territories to their offspring. Replacement occurred within hours of the removal and territory boundaries of the new squirrels were not significantly different from those of the original territory owners. Neighbouring territorial residents did not expand their territories to occupy all or part of the vacated area. The location of territory boundaries were not affected by intruder pressure.

scholarly journals Food availability affects habitat use of Eurasian red squirrels (Sciurus vulgaris) in a semi-urban environment

2016 ◽  
Vol 97 (6) ◽  
pp. 1543-1554 ◽  
Author(s):  
Stephanie Reher ◽  
Kathrin H. Dausmann ◽  
Lisa Warnecke ◽  
James M. Turner
Keyword(s):  
Habitat Use ◽  
Urban Environment ◽  
Food Availability ◽  
Sciurus Vulgaris ◽  
Red Squirrels

Female Red Squirrel (Tamiasciurus hudsonicus) Reproductive Tracts from Fenitrothion Treated and Untreated Forest of Southeastern New Brunswick

1986 ◽  
Vol 62 (4) ◽  
pp. 233-235 ◽  
Author(s):  
Louis LaPierre
Keyword(s):  
New Brunswick ◽  
Coniferous Forest ◽  
Tamiasciurus Hudsonicus ◽  
Corpora Lutea ◽  
Red Squirrel ◽  
Probability Level ◽  
Red Squirrels ◽  
August 15Th ◽  
Student’S T ◽  
Student’S T Test

Between August 15th and September 15th 1979, 1980 and 1981, 77 and 74 red squirrels, Tamiasciurus hudsonicus, were captured within the sprayed and unsprayed coniferous forest of southeastern New Brunswick. Following live capture, the squirrels were sacrificed, weighed and the reproductive tracts were removed and preserved in a 10% formalin solution.Counts of placental scars and corpora lutea of squirrels that inhabited the sprayed forest had a mean placental scar count of 3.8 and a mean corpora lutea count of 4.2. Squirrels from the unsprayed coniferous forest had a mean placental count of 3.6 and a corpora lutea count of 3.9. Statistical analyses, using the student's T-test with a probability level of 0.05, revealed no significant differences in reproductive success of the two groups of squirrels.

Effect of temperature and acclimation upon FFA levels in three species of rodents

1971 ◽  
Vol 49 (3) ◽  
pp. 303-305 ◽  
Author(s):  
J. Homer Ferguson ◽  
G. Edgar Folk Jr.
Keyword(s):  
Cold Acclimation ◽  
Cold Exposure ◽  
Tamiasciurus Hudsonicus ◽  
Effect Of Temperature ◽  
Red Squirrel ◽  
Short Term ◽  
Red Squirrels ◽  
White Rats ◽  
Short Term Exposure ◽  
Rats And Mice

Free fatty acid (FFA) levels were determined in warm- and cold-acclimated white rats, mice, and red squirrels (Tamiasciurus hudsonicus). FFA concentrations of the genetically cold-adapted species (red squirrel) were highest and reflect its ability to maintain high metabolic rates reported by others. In the red squirrels, FFA concentrations were elevated after cold acclimation. Acclimation of white rats and mice had no effect on FFA levels. Short-term cold exposure (−35 °C) caused the FFA levels to rise in all three species. Cold-exposed mice were found to be highest in plasma FFA content. The ability of the red squirrels to mobilize FFA during short-term exposure was enhanced by cold acclimation. The response of rats and mice to cold exposure was not changed by acclimation. This would indicate a greater capacity of the red squirrel to respond to acclimating conditions.

Male-biased adult sex ratios in a red squirrel population

1987 ◽  
Vol 65 (5) ◽  
pp. 1284-1286 ◽  
Author(s):  
T. Andrew Hurly
Keyword(s):  
Sex Ratio ◽  
Habitat Use ◽  
Sex Ratios ◽  
Sexual Differences ◽  
Differential Mortality ◽  
Red Squirrel ◽  
Red Squirrels ◽  
Male Mortality ◽  
Adult Sex Ratio ◽  
Sampling Biases

A 3-year study of a red squirrel population revealed that the adult sex ratio was biased towards males. There is no evidence that the skewed sex ratio was prejudiced by sampling biases due to sexual differences in mobility, observability, trappability, or habitat use. The tertiary juvenile sex ratio was even and therefore not the cause of the biased adult sex ratio. The data suggest that the skewed sex ratio may be the result of differential mortality. This is consistent with other reports of higher female than male mortality in red squirrels.

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