Yellow-pine chipmunk

Yellow Pine Chipmunk

The yellow-pine chipmunk (Tamias amoenus) is a species of order Rodentia in the Sciuridae family. It is found in western North America: parts of Canada and the United States.

These chipmunks are normally found in brush covered areas, and in California, they inhabit an elevation range of approximately 975 meters to 2,900 meters.

Characters

Body color is dark, reddish, mixed with cinnamon, with 5 longitudinal dark (black or mixed black) stripes that are separated by 4 lighter stripes—the outer pair of pale stripes is creamy white and narrower, the more median pair lighter stripes is a gray or smoke gray; the sides of the head each have 3 dark stripes, with 2 lighter in between, and the crown is black or smoke gray.

Males and females have similar brain size and approximate same size tail length, ear length from notch, and length of lower tooth row, but females prove larger in other body measurements; average body mass varies, with large males showing average of 49.7 g and large females averaging 53.5 g. Though male-biased sexual size dimorphism is common among mammals, T. amoenus exhibits female-biased sexual size dimorphism.

Feeding

Yellow pine chipmunks are seed storing hibernators who's fitness in winter and spring seasons is influenced by their availability of resources and foraging behaviors in the summer and autumn months. Since they do not build body fat before hibernation, their larder, or winter food supply they have built, serves as a measure for their likelihood of survival through the winter and of their reproductive success come spring. During the warm, active season the chipmunks gather accessible seeds and scatter-hoard the seeds in various caches, only to retrieve them later for their larder. T. amoenus avoids cache overlap with its loads, and mean nearest-neighbor distance ranges from 1.4-4.9 m--these distances between caches increases the farther T.amoenus gets from its food source.

Reproduction

Both sexes have genital bones; males possess a baculum and females a baubellum. Post-hibernation, there is one annual breeding event that takes place in late April/early May; male testes size are enlarged at this time (bolstered by the warmer temperatures); similarly, enlargement of female ovaries and uteri is also seen. The females are in estrus for one day, and 3 to 5 days prior they make vocalizations, making males aware of their readiness to reproduce and eliciting intrasexual selection among males. The female mates with one or more of the males that has come to her den. The average litter number is 4 or 5 and birth occurs late May/early June; in a litter of 6, young are smaller, suggesting physical constraints on the mother; the lactation period lasts approximately 2 months, and by beginning of September the young are of comparable size to others in the population. Female reproductive success has been observed to be significantly related to body size, whereas male reproductive success is independent of.