Table 1.

Animal characteristics

	Summer (n = 10)	Winter (n = 9)	P (Summer vs. Winter)
Body wt, g	211.54 ± 6.98	156.44 ± 13.58	0.0017
Heart wt, mg	896 ± 33.93	932 ± 31.13	0.4514
Tibia length, mm	34.30 ± 0.21	33.89 ± 0.42	0.3833
Heart wt/body wt, mg/g	4.30 ± 0.27	5.96 ± 0.36	0.0017
Heart wt/tibia length, mg/mm	26.17 ± 1.11	27.46 ± 1	0.4089
Body temperature, °C		6.96 ± 0.28

Values are means ± SE. Ground squirrels studied in summer (July) were significantly heavier than those studied in winter (January). Heart weights and tibia lengths were not significantly different. Heart weight-to-body weight ratios were significantly different, but this was due to differences in body weight, as heart weight-to-tibia length ratios were not significantly different between groups. P values were determined by unpaired 2-tailed t-test.