BAT LONGEVITY AND METABOLIC RATE

Rubner's hypothesis that metabolic rate is a major factor in determining longevity was considered by comparing data on temperate and tropical bats. Body temperatures and metabolic data indicate considerably higher energy expenditure for tropical species. A review of longevity records and population survival rates suggests that bats as a whole have long life spans. The present records are a function of banding effort and an increasing number of old bats are being recovered in tropical species. An examination of reproductive capacity shows most species, whether temperate or tropical, have only one reproductive period per year when the female gives birth to one young. There is no evidence of a higher reproductive rate in tropical forms which might be expected if they had a higher mortality rate than temperate species. Thus, in spite of the fact that the metabolic rates of tropical species are higher than their temperate counterparts, warm climate forms do not appear to have a shorter maximum life span.