Behaviour and use of space by juvenile Columbian ground squirrels (Spermophilus columbianus)

1986 ◽  
Vol 64 (5) ◽  
pp. 1121-1127 ◽  
Author(s):  
Jane M. Waterman
Keyword(s):  
Ground Squirrel ◽  
Site Fidelity ◽  
Ground Squirrels ◽  
Home Ranges ◽  
Male Dispersal ◽  
Spermophilus Columbianus ◽  
Males And Females ◽  
The Mean ◽  
Columbian Ground Squirrels ◽  
Behavioural Ontogeny

The behavioural ontogeny of the Columbia ground squirrel (Spermophilus columbianus) was examined using livetrapped and marked individuals in a population in southwestern Alberta, Canada. Observations using scan and all-occurrence sampling recorded the activities and locations of individuals. Differences between sexes in the movement of juvenile squirrels were apparent after the first 10 days from emergence from the natal burrow. Males travelled further from the natal burrow, had larger home ranges, and shifted their activity centres more than did females. Females remained nearest their sisters and rates of play between sisters were the highest of all interacting pairs. Although there was no difference in the mean distance from the mother for males and females, females greeted their mothers three times more frequently than did brothers. The consequences of such different social and spatial experiences are discussed in light of female site fidelity and male dispersal.

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.

Intraspecific killing of preweaned young in the Columbian ground squirrel, Spermophilus columbianus

1991 ◽  
Vol 69 (3) ◽  
pp. 797-800 ◽  
Author(s):  
James F. Hare
Keyword(s):  
Ground Squirrel ◽  
Ground Squirrels ◽  
Equal Access ◽  
Male And Female ◽  
Spermophilus Columbianus ◽  
Columbian Ground Squirrels

The abandonment of Columbian ground squirrel (Spermophilus columbianus) neonates by their dams when dams and litters were released from field enclosures resulted in the availability of newborn pups aboveground to male and female conspecifics. Four incidents of infanticide were observed and, without exception, perpetrators of infanticide were female, although male conspecifics had equal access to pups. Contrary to an earlier conjecture that male Columbian ground squirrels are the more likely perpetrators of infanticide, this finding is consistent with the majority of incidents documented for this species.

Intercolony natal dispersal in the Columbian ground squirrel

1989 ◽  
Vol 67 (1) ◽  
pp. 42-50 ◽  
Author(s):  
Darwin R. Wiggett ◽  
David A. Boag
Keyword(s):  
Ground Squirrel ◽  
Survival Rates ◽  
Ground Squirrels ◽  
Natal Dispersal ◽  
Male And Female ◽  
Spermophilus Columbianus ◽  
Median Distance ◽  
In Transit ◽  
Columbian Ground Squirrels ◽  
Actual Survival

Dispersal of Columbian ground squirrels (Spermophilus columbianus) among 16 colonies located in the Sheep River – Gorge Creek drainage of southwestern Alberta was studied from 1973 to 1986. In total, 73 intercolony movements involving 66 different animals were recorded. Intercolony dispersal movements were strongly biased towards males and were almost exclusively undertaken by 1-year-old squirrels (yearlings). The timing of emigration from the colonies studied was highly synchronous and was correlated with the dates of emergence of new litters. Yearling females that dispersed tended to leave at a later date than did yearling males. Most (91%) animals that dispersed moved to colonies <4 km away but movements of up to 8.5 km were recorded. There was no difference in median distance dispersed for male and female yearlings (2.0 and 1.8 km, respectively). Dispersing squirrels departed from colonies in nonrandom directions apparently following such features as trails and drainage systems. Such movement seemed to enhance the squirrels' chances of successfully locating nearby colonies. Minimum known survival rates while in transit for yearlings were 16% for males and 11% for females. Estimates of actual survival in transit for yearlings were 26% for males and 30% for females.

The proximate causes of male-biased natal emigration in Columbian ground squirrels

1993 ◽  
Vol 71 (1) ◽  
pp. 204-218 ◽  
Author(s):  
Darwin R. Wiggett ◽  
David A. Boag
Keyword(s):  
Ground Squirrels ◽  
Home Ranges ◽  
Adult Males ◽  
Spermophilus Columbianus ◽  
Adult Females ◽  
Study Support ◽  
Proximate Causes ◽  
Natal Home ◽  
And Behavior ◽  
Columbian Ground Squirrels

The results of this study support the hypothesis that male-biased emigration of yearling male Columbian ground squirrels (Spermophilus columbianus) is socially induced. The likelihood of emigration from both the natal site and the natal colony was correlated with parameters of social structure and behavior. Agonism by the mother and (or) neighboring adult females, in association with parturition and lactation, apparently caused the initial shifts of yearling males away from their natal home ranges. After these shifts, yearling males that lived in areas where the number of neighboring males (both adult and yearling) was high relative to the number of females emigrated to areas within the natal colony that were more female-biased (intracolony emigration), or emigrated from the natal colony (intercolony emigration). Reduced numbers of adult males apparently resulted in lower rates of emigration by yearling males. Among the latter, emigrants appeared to be subordinate to non-emigrants. We discuss these findings in light of current hypotheses concerning the proximate and ultimate causes of emigration in ground-dwelling sciurids.

Food and space: resources defended by territorial parous female Columbian ground squirrels

1994 ◽  
Vol 72 (11) ◽  
pp. 1908-1914 ◽  
Author(s):  
David A. Boag ◽  
Darwin R. Wiggett
Keyword(s):  
Body Mass ◽  
Significant Role ◽  
Ground Squirrel ◽  
Ground Squirrels ◽  
Differential Treatment ◽  
Adult Males ◽  
Spermophilus Columbianus ◽  
Columbian Ground Squirrels ◽  
Experimental Plots

The importance of food and space, as resources defended by parous female Columbian ground squirrels (Spermophilus columbianus), was studied by manipulating one of these resources, that is increasing the quality of forage (through urine fertilization) on small plots within territories. Use of these fertilized plots by ground squirrels increased more than 100-fold when averaged over 2 years after manipulation. This increase, however, was not equal for each sex and age class: parous females used the fertilized plots relatively more, and nonparous females less, than either yearling or adult males. The number of parous females with territories overlapping the experimental plots also increased after fertilization, but the size of their territories declined only slightly, by less than 10%. Parous females with access to the fertilized plots, relative to those without such access, had greater body mass and larger litters that both weighed more at birth and gained body mass subsequently more rapidly. Parous females on territories with fertilized plots showed higher levels of agonism than those on territories lacking such plots. Most of the agonism was centered on the experimental plots and more of it was directed at young of other females than at their own young. Such differential treatment of kin, however, did not extend to their offspring of the previous year. We suggest that for parous females of this ground squirrel, both food and space (at least that normally needed to supply sufficient forage) are important resources to defend, and both may have played a significant role in the evolution of territoriality in females of this species.

Movements of intercolony natal dispersers in the Columbian ground squirrel

1989 ◽  
Vol 67 (6) ◽  
pp. 1447-1452 ◽  
Author(s):  
Darwin R. Wiggett ◽  
David A. Boag ◽  
April D. R. Wiggett
Keyword(s):  
Ground Squirrel ◽  
Ground Squirrels ◽  
Suitable Habitat ◽  
Forest Habitat ◽  
Spermophilus Columbianus ◽  
Montane Meadow ◽  
Columbian Ground Squirrels

Eight yearling male Columbian ground squirrels (Spermophilus columbianus) were radio-collared in an attempt to document emigration from an isolated montane meadow in southwestern Alberta. Six of the eight squirrels emigrated from the meadow over a 14-day period. All six dispersers departed during the first half of the day, before 13:30. Four of the squirrels were known to have travelled briefly in and out of the forest habitat bordering the meadow before emigrating, possibly searching for exit routes. During emigration, squirrels moved quickly (up to 4.0 km/h) over relatively long distances, stopping occasionally for extended periods of time [Formula: see text]. Emigrating squirrels followed cutbanks along natural drainages, roads, and game trails; routes tended to interconnect patches of suitable ground squirrel habitat. While dispersing, five of the six emigrants were known to have encountered such patches within 10 km of the natal colony. None of the squirrels died while being tracked and four squirrels were known to have settled either temporarily (two) or permanently (two) in patches of suitable habitat. The latter settled permanently in meadows where other animals were present and the former in meadows without resident squirrels but where refuges (artificial burrows or log piles) had been provided.

The resident fitness hypothesis and dispersal by yearling female Columbian ground squirrels

1992 ◽  
Vol 70 (10) ◽  
pp. 1984-1994 ◽  
Author(s):  
Darwin Wiggett ◽  
David A. Boag
Keyword(s):  
Resource Availability ◽  
Ground Squirrels ◽  
Home Ranges ◽  
Adult Males ◽  
Data Set ◽  
Individual Basis ◽  
Spermophilus Columbianus ◽  
Adult Females ◽  
Fitness Benefits ◽  
Columbian Ground Squirrels

The emigratory behavior of yearling female Columbian ground squirrels (Spermophilus columbianus) in southwestern Alberta was studied for 25 active seasons among five colonies. From this data set we tested six predictions of the resident fitness hypothesis. The data strongly supported all six predictions: (1) yearling females were highly philopatric; (2) mothers behaved cohesively towards their yearling daughters (adult females tended to shift their home ranges in the presence of yearling daughter(s), often facilitating the recruitment of the latter to the natal site); (3) as densities of adult resident females rose and resource availability on an individual basis presumably declined, agonism from parous mothers and neighboring females caused greater proportions of yearling females to emigrate; (4) sibling daughters competed for access to the natal site when this space became vacant (parous yearlings were more successful than their nonparous siblings, and among the latter, dominant individuals were more successful than their subordinate siblings); (5) resident adult females were highly aggressive towards immigrant yearling females; and (6) resident adult males behaved cohesively with all yearling females, whether resident or immigrant, and were significantly more cohesive towards yearling females than towards yearling males. The results of this study suggest that emigration is not adaptive for yearling female Columbian ground squirrels. Rather, we suggest that female Columbian ground squirrels gain fitness benefits through philopatry and the retention of daughter(s) on the natal site when resources are not limiting.

The effects of capital on an income breeder: evidence from female Columbian ground squirrels

2005 ◽  
Vol 83 (4) ◽  
pp. 546-552 ◽  
Author(s):  
David R Broussard ◽  
F Stephen Dobson ◽  
J O Murie
Keyword(s):  
Path Analysis ◽  
Observational Data ◽  
Life Histories ◽  
Reproductive Investment ◽  
Ground Squirrels ◽  
Initial Capital ◽  
Spermophilus Columbianus ◽  
Live Trapping ◽  
Investment In Reproduction ◽  
Columbian Ground Squirrels

To maximize fitness, organisms must optimally allocate resources to reproduction, daily metabolic maintenance, and survival. We examined multiple years of live-trapping and observational data from a known-aged population of female Columbian ground squirrels, Spermophilus columbianus (Ord, 1815), to determine the influences of stored resources and daily resource income on the reproductive investments of females. We predicted that because yearling females were not fully grown structurally while producing their first litter, they would rely exclusively on income for reproduction, while reproductive investment in older females (≥2 years of age) would be influenced by both stored resources (capital) and daily income. Results from path analysis indicated that both yearlings and older females were income breeders. However, initial capital indirectly influenced investment in reproduction of yearling and older females. Females with the greatest initial capital maintained high body masses while investing relatively more income in reproduction. By considering influences of both capital and income, important relationships can be revealed between these resources and their influence on life histories.

Variation in reproductive success of male and female Columbian ground squirrels (Urocitellus columbianus)

2012 ◽  
Vol 90 (6) ◽  
pp. 736-743 ◽  
Author(s):  
Philip H. Jones ◽  
Jeffrey L. Van Zant ◽  
F. Stephen Dobson
Keyword(s):  
Reproductive Success ◽  
Mating System ◽  
Multiple Paternity ◽  
Ground Squirrels ◽  
Male Reproductive Success ◽  
Offspring Production ◽  
Bateman Gradient ◽  
Coefficients Of Variation ◽  
Males And Females ◽  
Columbian Ground Squirrels

The imbalanced reproductive success of polygynous mammals results in sexual selection on male traits like body size. Males and females might have more balanced reproductive success under polygynandry, where both sexes mate multiply. Using 4 years of microsatellite DNA analyses of paternity and known maternity, we investigated variation in reproductive success of Columbian ground squirrels, Urocitellus columbianus (Ord, 1815); a species with multiple mating by both sexes and multiple paternity of litters. We asked whether male reproductive success was more variable than that of females under this mating system. The overall percentage of confirmed paternity was 61.4% of 339 offspring. The mean rate of multiple paternity in litters with known fathers was 72.4% (n = 29 litters). Estimated mean reproductive success of males (10.27 offspring) was about thrice that of females (3.11 offspring). Even after this difference was taken into account statistically, males were about three times as variable in reproductive success as females (coefficients of variation = 77.84% and 26.74%, respectively). The Bateman gradient (regression slope of offspring production on number of successful mates) was significantly greater for males (βM = 1.44) than females (βF = 0.28). Thus, under a polygynandrous mating system, males exhibited greater variation in reproductive success than females.

Weight in relation to sex, age, and season in Columbian ground squirrels (Sciuridae: Rodentia)

1981 ◽  
Vol 59 (6) ◽  
pp. 999-1004 ◽  
Author(s):  
D. A. Boag ◽  
J. O. Murie
Keyword(s):  
Weight Gain ◽  
Ground Squirrels ◽  
Full Potential ◽  
Age Classes ◽  
Adult Weight ◽  
Spermophilus Columbianus ◽  
Large Colony ◽  
Potential Weight ◽  
Columbian Ground Squirrels

Annual weight gain in Columbian ground squirrels (Spermophilus columbianus) was studied over a period of 7 years in a large colony in southwestern Alberta. Juveniles approximately tripled their weight during the period from emergence to immergence, achieving about 60% of adult weight at onset of their first hibernation. Males were heavier than females and the weight gain in both sexes varied significantly among years. The weight characteristics of the age-classes up to 3 years were different from one another. Full potential weight was not achieved until squirrels were in their fourth summer. Males were always significantly heavier than females in nonjuvenile squirrels and the amount of weight gained by these classes varied significantly among years.

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