Effect of climatic conditions on the annual activity and hibernation cycle of Richardson's ground squirrels and Columbian ground squirrels

1977 ◽  
Vol 55 (4) ◽  
pp. 693-703 ◽  
Author(s):  
Gail R. Michener
Keyword(s):  
Rocky Mountains ◽  
Climatic Conditions ◽  
Ground Squirrels ◽  
Active Season ◽  
Southern Alberta ◽  
Annual Activity ◽  
The Times ◽  
Columbian Ground Squirrels ◽  
Spring Emergence ◽  
Species Ecology

In 1975 and 1976 the times of spring emergence, breeding, and entry into hibernation were compared for Spermophilus richardsonii and S. columbianus in an area of sympatry in the foothills of the southern Alberta Rocky Mountains. Both species emerged earlier in 1976, which had a warmer than normal spring, than in 1975, which had a cooler than normal spring. In both years S. richardsonii emerged earlier than S. columbianus and remained active longer. Juvenile S. richardsonii entered hibernation when 17–20 weeks old whereas juvenile S. columbianus were 10–11 weeks old. Yearling S. richardsonii bred, whereas yearling S. columbianus did not. Breeding success affected the time of entry into hibernation but not the time of emergence from hibernation in the next spring. A possible relationship between the periodic arousals during hibernation and the emergence pattern of squirrels in spring is discussed. The significance of flexibility of spring emergence, length of the active season, and age at breeding to survival and species ecology is considered.

Effects of reproduction on activity and foraging behaviour of adult female Columbian ground squirrels

1991 ◽  
Vol 69 (8) ◽  
pp. 2209-2216 ◽  
Author(s):  
R. Bruce MacWhirter
Keyword(s):  
Adult Female ◽  
Foraging Behaviour ◽  
Ground Squirrels ◽  
Absolute Amount ◽  
Short Term ◽  
Trade Off ◽  
Active Season ◽  
Spermophilus Columbianus ◽  
Time Of Breeding ◽  
Columbian Ground Squirrels

In this study I evaluated six ways in which adult female Columbian ground squirrels (Spermophilus columbianus) potentially alter their overall activity and foraging behaviour to satisfy the increased energetic needs of reproduction, all of which may involve a trade-off with predation risk. A sample of nonparous females was obtained by administering a short-term chemosterilant at the time of breeding. Relative to nonparous females, parous females spent more time above ground, more time foraging, and less time vigilant, particularly during lactation, and had a longer active season. Thus, in absolute terms, parous females spent more time exposed to aboveground predators than did nonparous females. Parous females spent less time at burrow entrances and, during lactation, were active farther from escape burrows than were nonparous females. Parous and nonparous females did not differ in the percentage of time spent vigilant during foraging bouts. These results indicate that females respond to the energetic demands of reproduction by increasing the absolute amount of time spent foraging, which entails an acceptance of an increase in exposure to predators, and not by modifying their behaviour during foraging bouts.

Territoriality in adult female Columbian ground squirrels

1982 ◽  
Vol 60 (5) ◽  
pp. 1060-1066 ◽  
Author(s):  
Marco Festa-Bianchet ◽  
David A. Boag
Keyword(s):  
Adult Female ◽  
Adaptive Significance ◽  
Ground Squirrels ◽  
Late Gestation ◽  
Spermophilus Columbianus ◽  
Behavioral Observations ◽  
Female Territoriality ◽  
Small Home Range ◽  
Columbian Ground Squirrels ◽  
Spring Emergence

The spatial relationships among adult female Columbian ground squirrels (Spermophilus columbianus) were investigated through intensive behavioral observations at an isolated, high-density colony in southwestern Alberta in 1979 and 1980. Population size at spring emergence more than doubled during the study mainly through an increase in number of yearlings. Each adult female established a small home range and actively defended part of it as a territory. All intruding females were chased out, but exclusive use was not achieved. Territorial behavior increased after breeding, declined during late gestation, peaked during lactation, and decreased again after juveniles emerged. The adaptive significance of female territoriality seems to be related mainly to protection of juveniles.

scholarly journals Mortality in relation to season, age, sex, and reproduction in Columbian ground squirrels (Spermophilus columbianus)

2001 ◽  
Vol 79 (3) ◽  
pp. 465-470 ◽  
Author(s):  
P Neuhaus ◽  
N Pelletier
Keyword(s):  
Ground Squirrels ◽  
Reproductive Status ◽  
Adult Males ◽  
Active Season ◽  
Life History Data ◽  
Spermophilus Columbianus ◽  
Trade Offs ◽  
Maternal Survival ◽  
Mortality Increase ◽  
Columbian Ground Squirrels

We investigated the timing of and age at mortality in Columbian ground squirrels (Spermophilus columbianus) in relation to sex and reproductive status. Life-history data were collected from 1994 to 1999 in the foothills of the Rocky Mountains, Alberta, Canada. We predicted increased mortality for males during mating and for females during lactation. Further, we expected reproductively successful females to have higher mortality than females that did not reproduce successfully. Finally we assumed that at some age reproductive success of females would decrease and mortality increase because of old age. For both sexes, survival over winter was high (ca. 90%) for adults. While there was a significant increase in mortality of adult males during the mating season, females did not have higher mortality during lactation than during the rest of the active season. Reproductive status influenced mortality in females: non-reproducing females had a higher chance of surviving than reproducing females. Females that weaned young were more likely to die after the weaning period than females that lost their litter during lactation. There was a positive correlation between maternal survival and survival of offspring to yearling age. Our results showed evidence of trade-offs between reproduction and survival of male and female Columbian ground squirrels.

Behavior and dispersal of yearling Columbian ground squirrels

1984 ◽  
Vol 62 (2) ◽  
pp. 161-167 ◽  
Author(s):  
Marco Festa-Bianchet ◽  
Wendy J. King
Keyword(s):  
Ground Squirrels ◽  
Dispersion Pattern ◽  
Dominance Status ◽  
Similar Frequency ◽  
Active Season ◽  
Spermophilus Columbianus ◽  
Play Behaviors ◽  
Intensive Observations ◽  
Columbian Ground Squirrels ◽  
Density Population

Behavior of yearling Columbian ground squirrels (Spermophilus columbianus) was studied through intensive observations of an isolated, high-density population in southwestern Alberta from 1979 to 1981. All members of this population were individually marked. A greater proportion of yearlings disappeared during the active season than that of any other age-class. This loss appeared to be due to emigration, and was greater for males than for females. Some 2-year-old males may also have dispersed. Male yearlings played more than females, but both sexes displayed a similar frequency of aggressive interactions with other yearlings. As the season progressed, the frequency of play behaviors between yearlings decreased, and by the time of presumed emigration almost no play was seen. There was no clear relationship between a yearling's dominance status and whether it emigrated. Adults of both sexes behaved aggressively towards yearlings, particularly yearling males. Adult females were most aggressive just preceding the time of presumed emigration, and at this time yearlings changed their dispersion pattern within the meadow, apparently in an attempt to avoid female aggression. Postponement of dispersal to the yearling age appears to be an adaptation to a short active season. Adult squirrels may benefit from expelling yearlings by diminishing future competition, but the adaptive advantage of emigration for the yearlings themselves remains unclear.

The use of space by yearling Columbian ground squirrels before male dispersal

1992 ◽  
Vol 70 (12) ◽  
pp. 2490-2493 ◽  
Author(s):  
Jane Waterman
Keyword(s):  
Spatial Patterns ◽  
Ground Squirrel ◽  
Ground Squirrels ◽  
Natal Philopatry ◽  
Use Of Space ◽  
Male Dispersal ◽  
Spermophilus Columbianus ◽  
Proximate Causes ◽  
Columbian Ground Squirrels ◽  
Spring Emergence

The development of spatial patterns relevant to natal philopatry and dispersal was examined in yearling Columbian ground squirrels, Spermophilus columbianus. Observations using scan and all-occurrence sampling recorded the activities and locations of 56 yearlings in a population in southwestern Alberta. Yearling males moved greater distances from spring emergence to the time of dispersal from the colony. Females were more restricted in their movements, with no increase in the maximum distance moved over the summer. Early movement patterns of males reflected patterns of later dispersal, whereas females appeared to centre their activities on the natal area. These differences are discussed in light of the proximate causes of dispersal in the Columbian ground squirrel.

Seasonal activity and body mass of Columbian ground squirrels

1992 ◽  
Vol 70 (7) ◽  
pp. 1364-1368 ◽  
Author(s):  
F. Stephen Dobson ◽  
Michael J. Badry ◽  
Christine Geddes
Keyword(s):  
Body Mass ◽  
Growing Season ◽  
High Elevation ◽  
Ground Squirrels ◽  
Adult Males ◽  
Active Season ◽  
Spermophilus Columbianus ◽  
High Elevations ◽  
Columbian Ground Squirrels ◽  
Plant Growing Season

Recent research on Columbian ground squirrels (Spermophilus columbianus) has invoked the lengths of the active season and plant growing season to explain differences in life history and social behaviours among populations at different elevations. We evaluated an assumption of these studies that the active season for individual ground squirrels is significantly shorter at high than at low elevation. Adult males and females were active for about 100 days at low elevation and about 86 days at high elevation. Juvenile ground squirrels also had a longer active season at low (50 days) than at high elevation (45 days), but for yearlings the active season was similar (about 87 days). The active season for adults was about 2 weeks shorter than the plant growing season at low elevation, but up to 2 weeks longer than the plant growing season at high elevation. Differences in body mass of adult ground squirrels between low and high elevations at spring emergence from hibernation and at fall immergence into hibernation were consistent with a shorter active season and lower annual energy intake at high elevation, where adults were generally lighter. Examination of rates of weight gain during the active season showed that differences in adult weight could be explained by the length of the active season, but that yearlings and juveniles grew more rapidly at low than at high elevation. These results support the assumption that the active season for individual ground squirrels is generally shorter at high than at low elevation.

Effect of brief exposure to a potential predator on cortisol concentrations in female Columbian ground squirrels (Spermophilus columbianus)

2000 ◽  
Vol 78 (4) ◽  
pp. 578-587 ◽  
Author(s):  
Anne H Hubbs ◽  
John S Millar ◽  
John P Wiebe
Keyword(s):  
Blood Sample ◽  
Canis Familiaris ◽  
Ground Squirrels ◽  
Cortisol Response ◽  
Potential Predator ◽  
Active Season ◽  
Spermophilus Columbianus ◽  
Free Cortisol ◽  
Cortisol Levels ◽  
Columbian Ground Squirrels

We examined the effect of exposure to a potential predator on cortisol concentrations in captive female Columbian ground squirrels (Spermophilus columbianus) and determined if lactation mitigated this cortisol response. Lactating and nonlactating females were exposed to a dog (Canis familiaris) for 5 min once a week over a 8-week period. Blood was collected 5 min and 2.5 and 4.5 h after exposure to the dog. Females exposed to the dog had higher concentrations of total (but not free) cortisol than unexposed females only in the 5-min blood sample. Over the active season, total- and free-cortisol levels were 37-47% higher in females exposed to the dog than in unexposed females in early to mid-July when young were being weaned. The cortisol response to the dog was suppressed during lactation. Cortisol levels were, on average, 41-59% lower during lactation than during nonlactation 5 min (but not 2.5 or 4.5 h) after exposure to the dog.

Annual reproductive success in three cohorts of Columbian ground squirrels: founding immigrants, subsequent immigrants, and natal residents

1993 ◽  
Vol 71 (8) ◽  
pp. 1577-1584 ◽  
Author(s):  
Darwin R. Wiggett ◽  
David A. Boag
Keyword(s):  
Reproductive Success ◽  
Survival Rates ◽  
Ground Squirrels ◽  
Central Position ◽  
Adult Males ◽  
Male And Female ◽  
Reproductive Maturity ◽  
Active Season ◽  
Risk Of Predation ◽  
Columbian Ground Squirrels

We compared, over an 8-year period, the annual reproductive success (RS) of male and female founding immigrants (FIs) with that of subsequent immigrants (SIs), and the latter with that of natal residents (NRs) in two recently established colonies of Columbian ground squirrels (Spermophilus columbianus) in southwestern Alberta. For males, actual annual RS was unknown and so was estimated; for females, RS was measured directly. Among females, FIs had significantly more juveniles at litter emergence, and more yearlings present to age of emigration annually than did SIs. Juvenile and yearling offspring of SI females suffered higher annual rates of disappearance (presumed mortality) over the active season than did those of FIs. Additionally, the matrilines of FIs produced significantly more juveniles, more yearlings to time of emigration, and more daughters to reproductive maturity annually than did the matrilines of SI females. Male FIs had higher annual survival rates (and consequently lived and were territorial significantly longer), and had more female neighbours per year than did SIs, which suggests that the former had higher annual RS. We suggest that the higher annual RS of male and female FIs resulted mainly from their monopolization of the best resources and a lower risk of predation as a result of their more central position in the colony. Comparison of the annual RS of SIs and NRs showed that most (~70%) adult males present in the colonies were SIs. These males were significantly more likely to hold territories and to do so for significantly longer periods than their NR counterparts. Conversely, SI females annually brought above ground significantly fewer juveniles and had significantly fewer yearling offspring present to time of emigration than did NR females. Furthermore, the young of SI females suffered significantly higher rates of disappearance (presumed mortality) during the active season than did those of NR females, possibly because the former resided in more peripheral areas within the colony where predation rates may have been higher. We found no differences between these groups of females in the number of female offspring reaching reproductive maturity in the natal colony. These results provide preliminary support for the hypothesis that females, apart from FIs, benefit from philopatry; whereas males gain reproductive advantage through dispersal.

scholarly journals Subtle short-term physiological costs of an experimental augmentation of fleas in wild Columbian ground squirrels

2019 ◽  
Vol 222 (12) ◽  
pp. jeb203588
Author(s):  
Jeffrey D. Roth ◽  
F. Stephen Dobson ◽  
François Criscuolo ◽  
Pierre Uhlrich ◽  
Alexandre Zahariev ◽  
...  
Keyword(s):  
Ground Squirrels ◽  
Short Term ◽  
Columbian Ground Squirrels
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