conservation.arizona.edu - body mass

Leonard, K. M. and J. L. Koprowski. 2009. Effects of fire on endangered Mt. Graham red squirrels (Tamiasciurus hudsonicus grahamensis): responses of individuals with known fates. Southwestern Naturalist 55:217-224.

thackerk1 — Tue, 23 Jul 2019 22:33:20 +0000

Authors

Katherine M. Leonard

John L. Koprowski

We studied demography and behavior of endangered Mount Graham red squirrels (Tamiasciurus hudsonicus grahamensis) inhabiting areas within and outside low-intensity burns following the Nuttall Fire in the Pinaleńo Mountains, Arizona. Body mass, proportion of individuals in reproductive condition, and distance squirrels traveled to nest did not differ between squirrels within and outside the perimeter of the fire. Within the perimeter, red squirrels had smaller home ranges and shifted territories less frequently and had shorter distances from their previously held territories than squirrels outside the perimeter. Mount Graham red squirrels evolved with patchy, low-intensity fires like those that burned in mixed-conifer forests in the Pinaleńo Mountains and may be able to persist in areas affected by this level of disturbance.

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EFFECTS OF FIRE ON ENDANGERED MOUNT GRAHAM RED SQUIRRELS (TAMIASCIURUS HUDSONICUS GRAHAMENSIS): RESPONSES OF INDIVIDUALS WITH KN

Date of publication:

2009

Topics

Mount Graham Red Squirrel

Pinaleño Mountains

body mass

fire

level of disturbance

Leonard, K. M. and J. L. Koprowski. 2009. A comparison of habitat use and demography of red squirrels at the southern edge of their range. American Midland Naturalist 162: 132-145.

thackerk1 — Tue, 23 Jul 2019 22:17:11 +0000

Authors

Kathrine M. Leonard

John L. Koprowski

Populations at the edge of their geographic range may demonstrate different population dynamics from central populations. Endangered Mt. Graham red squirrels (Tamiasciurus hudsonicus grahamensis), endemic to southeastern Arizona, represent the southernmost red squirrel population and are found at lower densities than conspecifics in the center of the range. To determine if differences are due to conditions at the southern periphery of the range, we compared habitat characteristics, demography, body mass, space use and nesting behavior with another subspecies located at the southern edge of the range, the Mogollon red squirrel (T. h. mogollonensis). We found that mean and minimum daily temperatures were higher at Mt. Graham whereas maximum temperatures were higher in the White Mountains, male Mogollon red squirrels were heavier than male Mt. Graham red squirrels in all seasons and female Mogollon red squirrels were slightly heavier than female Mt. Graham red squirrels in spring, proportion of squirrels in reproductive condition was lower in female Mogollon red squirrels, Mogollon red squirrels had smaller home ranges, used different types of nests and traveled less distance to nest than Mt. Graham red squirrels. There were no differences in annual rainfall, seedfall, habitat characteristics or survival between mountain ranges. Localized conditions appear to account for the disparity between populations. These differences demonstrate the importance of evaluating attributes of peripheral populations for maximizing persistence and intraspecific diversity.

Additional Information

A Comparison of Habitat Use and Demography of Red Squirrels at the Southern Edge of Their Range

Date of publication:

2009

Topics

Mount Graham Red Squirrel

Mongollon red squirrel

habitat use

body mass

nesting behavior

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

Female-biased sexual size dimorphism: ontogeny, seasonality, and fecundity of the cliff chipmunk (Tamias dorsalis)

thackerk1 — Mon, 22 Jul 2019 21:28:06 +0000

Authors

Allyssa L. Kilanowski

John L. Koprowski

Female-biased sexual dimorphism is uncommon in mammals and is usually attributed to increased fecundity of large females. Moreover, sexual dimorphism is usually described for adults, and the ontogeny of sex differences is poorly documented. We studied cliff chipmunks (Tamias dorsalis), a small mammal with female-biased sexual dimorphism, to describe development of sexual dimorphism in juveniles and to measure sexual dimorphism and seasonal body mass in adults. To test the fecundity hypothesis, we compared body mass of females to litter size and body mass of offspring. Juveniles were not sexually dimorphic at emergence from the nest and did not differ in body mass 2 months after emergence. Adult chipmunks maintained a relatively stable body mass in March–October with females consistently larger than males. Maternal mass did not have an effect on litter size or mass of juveniles. Because females were consistently larger than males, the ontogeny of sexual dimorphism may provide insights into selection pressures that lead to female-biased sexual dimorphism.

Additional Information

Journal of Mammalogy

Date of publication:

2016

Topics

body mass

cliff chipmunk

litter size

small mammal

female-biased sexual dimorphism

Arizona

Research Categories

Natural History Population Ecology Sky Islands