conservation.arizona.edu - sex differences

Koprowski, J. L. and M. C. Corse. 2005. Time budgets, activity periods, and behavior of mexican fox squirrels. Journal of Mammalogy 86(5): 947-952.

thackerk1 — Mon, 22 Jul 2019 23:31:09 +0000

Authors

John L. Koprowski

Michelle C. Corse

Resources that limit reproductive success differ between the sexes in many vertebrates. We used focal animal observations to determine sex-specific activity periods, time budgets, and movements of endemic Mexican fox squirrels (Sciurus nayaritensis chiricahuae) in montane forests of southeastern Arizona during June, August, and December 1994 and January 1995. Activity periods during summer were bimodal with peaks in morning and afternoon separated by a midday lull in activity; winter activity was unimodal. No sex differences were detected in activity periods, although males retired later than females in winter. Resting, feeding, and locomotion were the most common behaviors and accounted for .75% of activities of each sex. Activity by females did not differ between seasons. Males spent more time in locomotion in summer and more time feeding in winter than in other seasons. Differences in time budgets of the sexes suggest that males and females apportion daily activity to maximize access to resources that limit fitness of each sex.

Additional Information

TIME BUDGETS, ACTIVITY PERIODS, AND BEHAVIOR OF MEXICAN FOX SQUIRRELS

Date of publication:

2005

Topics

Arizona

sex differences

sexual dimorphism

Mexican fox squirrels

Koprowski, J. L. 2005. Annual cycles in body mass and reproduction of endangered Mt. Graham red squirrels. Journal of Mammalogy 86(2): 309-313

thackerk1 — Mon, 22 Jul 2019 23:18:39 +0000

Authors

John L. Koprowski

Annual cycles in life-history traits often are interpreted as adaptations. The Mt. Graham red squirrel (Tamiasciurus hudsonicus grahamensis) is an endangered species isolated in the Pinaleno Mountains of Arizona (United States) at the southernmost range terminus where the ecology is poorly known. I monitored annual cycles of reproduction and body mass in male and female Mt. Graham red squirrels. Males with scrotal testes were present during all months except October, with a peak in testis size in April. Lactating females were found from April to September. Male body mass was highest in winter and lowest in summer; females did not fluctuate seasonally in mass. Male body mass exceeded that of females during winter and was positively related to size of testes late in the breeding season. Annual cycles in reproduction and body mass of Mt. Graham red squirrels are similar to those of other red squirrels in similar life zones.

Additional Information

ANNUAL CYCLES IN BODY MASS AND REPRODUCTION OF ENDANGERED MT. GRAHAM RED SQUIRRELS

Date of publication:

2005

Topics

Arizona

body mass

mating systems

Mount Graham Red Squirrel

sex differences

energetics

Edelman, A. J. and J. L. Koprowski. 2006. Seasonal changes in home ranges of Abert's squirrels: Impact of mating season. Canadian Journal of Zoology 84: 404-411.

thackerk1 — Tue, 25 Jun 2019 01:06:09 +0000

Authors

A.J. Edelman

J.L. Koprowski

We compared home ranges of introduced Abert’s squirrels (Sciurus aberti Woodhouse, 1853) in mixed- conifer forests of Arizona during non-mating and mating seasons. Because Abert’s squirrels are reported to depend on ponderosa pine (Pinus ponderosa P. & C. Lawson) forests, the mixed-conifer forest in our study represented a novel habitat. Home-range size, home-range overlap with females, and movement distances increased for males from non-mating to mating seasons. Home-range size and overlap characteristics of females remained consistent between seasons, but movement distances were reduced during the mating season. Males probably increased home-range size, home-range overlap with females, and movement distances during the mating season to maximize contact with scarce females. Home-range size and overlap characteristics of female Abert’s squirrels likely remained stable between seasons because females do not search for mates. Restricted movements by females during the mating season may be due to changes in resource use in preparation for reproduction. Non-mating season home ranges in our study were smaller than home ranges observed in ponderosa pine forest. Abert’s squirrels in mixed-conifer forest may have small home ranges because resource quality is higher than in ponderosa pine forest or competition for space with co-occurring Mount Graham red squirrels (Tamiasciurus hudsonicus grahamensis (J.A. Allen, 1894)).

Additional Information

Seasonal changes in home ranges of Abert’s squirrels: impact of mating season

Date of publication:

2006

Topics

Abert’s squirrels

mixed conifer forests

home range

resource quality

sex differences

seasonal changes

mating season

Cudworth, N.L., J.L. Koprowski. 2010. Influences of mating strategy on space use of Arizona gray squirrels. Journal of Mammalogy. 91: 1235-1241.

thackerk1 — Mon, 24 Jun 2019 23:37:06 +0000

Authors

Nichole L. Cudworth

John L. Koprowski

Space use frequently differs between sexes and may reflect differences in parental investment and limiting resources. We examined Arizona gray squirrels (Sciurus arizonensis) from April 2007 to December 2008 to determine effects of mating strategy on patterns of home-range size and overlap. Home ranges were large compared to those of congeners, suggesting an environment with low availability and predictability of resources, and differed by sex and season. Females maintained smaller home ranges overlapped more by males than females; overlap by male home ranges increased during the breeding season. Males had larger home ranges that overlapped females more than males; home-range size and overlap of both sexes increased during the breeding season. Additionally, male Arizona gray squirrels appear to respond to the distribution of females by enlarging home ranges to maximize proportion of females overlapped. Consequently, Arizona gray squirrels conform to theoretical predictions, with female space use influenced by access to food and male space use influenced by access to mates.

Additional Information

Influences of mating strategy on space use of Arizona gray squirrels

Date of publication:

2010

Topics

Arizona gray squirrel

mating system

resource limitation

sex differences

reproductive strategies