conservation.arizona.edu - mating system

Ramos-Lara, N., and J. L. Koprowski. 2015. Spacing behavior of a non-larder-hoarding Tamiasciurus: a study of Mearns's squirrels in xeric coniferous forests. Ethology 121: 196-205.

thackerk1 — Tue, 30 Jul 2019 17:43:48 +0000

Authors

Nicolás Ramos-Lara

John L. Koprowski

In ecosystems with seasonal fluctuations in food supply many species use two strategies to store food: larder hoarding and scatter hoarding. However, because species at different geographic locations may experience distinct environmental conditions, differences in hoarding behavior may occur. Tree squirrels in the genus Tamiasciurus display variation in hoarding behavior. Whereas red (Tamiasciurus hudsonicus) and Douglas’s (Tamiasciurus douglasii) squirrels in mesic coniferous forests defend territories centered around larder hoards maintaining non-overlapping home ranges, red squirrels in deciduous forests defend small scatter-hoarded caches of cones maintaining overlapping home ranges. As in other rodent species, variation in hoarding behavior appears to influence the spacing behavior of red and Douglas’s squirrels. In contrast, Mearns’s squirrels (Tamiasciurus mearnsi) in xeric coniferous forests neither rely on larder hoards nor appear to display territorial behavior. Unfortunately, little is known about the ecology of this southernmost Tamiasciurus. Using radiotelemetry, we estimated home-range size, overlap, and maximum distance traveled from nest to examine the spacing behavior of Mearns’s squirrels. Similar to scatter-hoarding rodents, maximum distance traveled from nest was greater for males during mating season, whereas those of females were similar year round. Although no seasonal differences were detected, male home ranges were three times larger during mating season, whereas those of females were smaller and displayed a minor variation between seasons. Home ranges were overlapped year round but contrary to our expectations, overlap was greater during mating season for both sexes, with no detectable relationship between male home-range size and the number of females overlapped during mating season. Overall, the results appear to support our hypothesis that in the absence of larder hoards, the spacing behavior of Mearns’s squirrels should be different from larder- hoarding congeners and more similar to scatter-hoarding rodents.

Additional Information

Spacing Behavior of a Non-Larder-Hoarding Tamiasciurus: A Study of Mearns’s Squirrels in Xeric Coniferous Forests

Date of publication:

2014

Topics

hoarding behavior

mating system

spacing behavior

tree squirrel

Mearn’s squirrel

red squirrel

Douglas's squirrel

Pasch, B. and J. L. Koprowski. 2006. Sex differences in space use of Chiricahua fox squirrels. Journal of Mammalogy 87(2): 380-386.

thackerk1 — Wed, 24 Jul 2019 22:48:11 +0000

Authors

Bret Pasch

John L. Koprowski

Sex differences in reproductive investment influence space use patterns of many animals. In polygynous mammals, male space use reflects distribution of females and female space use reflects relative distribution of food. We used radiotelemetry to examine seasonal patterns of home-range size, overlap, and distance traveled by male and female Chiricahua fox squirrels (Sciurus nayaritensis chiricahuae) from 2002 to 2003. Male and female home-range and core-area size varied little between nonmating and mating seasons. Female core areas had a greater percentage overlap by males than by females during mating and nonmating seasons. Males traveled farther in the mating season and females showed little variation between seasons. Extreme spatial and temporal fluctuations of food experienced by Chiricahua fox squirrels may result in space use patterns that differ from those of tree squirrels living in forests with a greater abundance of food.

Additional Information

SEX DIFFERENCES IN SPACE USE OF CHIRICAHUA FOX SQUIRRELS

Date of publication:

2006

Topics

mating system

reproductive strategy

Chiricahua fox squirrel

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