Premium
The Influence of Body Size on the Energetics and Distribution of Fossorial and Burrowing Mammals
Author(s) -
McNab Brian K.
Publication year - 1979
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.2307/1936869
Subject(s) - fossorial , burrow , energetics , basal metabolic rate , biology , basal (medicine) , ecology , competition (biology) , zoology , endocrinology , insulin
The energetics of four fossorial mammals, Spalacopus cyanus, Cannomys badius, Aplodontia rufa, and Scalopus aquanticus, are examined and compared to data available in the literature. Basal rates of metabolism are lower than expected from mass if fossorial mammals weigh >80 g but they are higher than expected if they weigh <60 g. This conclusion also applies to mammals that spend only part of the time in burrows. The season that most hibernating rodents have low basal rates of metabolism is that they burrow and weigh >100 g. Small burrowers may have low basal rates unrelated to burrowing habits. Minimal thermal conductances in fossorial and burrowing mammals are usually near the expected values at masses <1 kg, unless these species live in warm burrows, in which case minimal conductances are high. Burrowing mammals weighing > 1 kg have high minimal conductances. The temperature differential maintained at the lower limit of thermoneutrality and at temperatures above thermoneutrality is proportional to the ratio of basal rate to minimal conductance. Adaptations to a burrowing habit include (1) maintaining a small temperature differential independent of mass, which is accomplished by matching the mass sensitivity of the basal rate to that of the minimal conductance, (2) reducing basal rate, (3) increasing minimal conductance, and (4) reducing mass. The limits that exist to a reduction in mass and a reduction in basal rate of metabolism and to an increase in minimal conductance result in geographical limits to the distribution of fossoial mammals, but not necessarily to the distribution of other burrowing mammals.