Effect of Temperature and Exercise on Energy Intake and Body Weight of the White-Throated Sparrow Zonotrichia albicollis

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Abstract
A standard amount of exercise was given daily to a group of birds for 12 of 14 hr. of darkness and compared at various temperatures with an unexercised group. The mean body weight of both groups increased with decreasing temperature down to -5[degree]C. Exercised birds, however, maintained lower weights than the unexercised birds at all temperatures. Weight gains during the day and losses during the night were significantly greater in the exercised than in the unexercised birds. The gross energy intake, as well as metabolized energy, increased linearly for both groups with decreasing temperature. The linear regression equations for metabolized energy were: kcal/bird-day = 28.75-.48T[degree]C for exercised, and kcal/bird-day = 23.05-.38T[degree]C for unexercised birds. The lower limit of temperature tolerance is approximately -29 [degree]C for unexercised birds, and approximately -11 [degree]C for the birds undergoing exercise, the maximum energy metabolized being approximately the same. The upper limit of temperature tolerance for both groups of birds was also determined.