Field energetics and foraging mode of Kalahari lacertid lizards
The authors examined the energetic costs associated with foraging mode in the widely foraging lizard Eremias lugubris (mean mass 3.83 g) and the sit-and-wait lizard Eremias lineoocellata (3.27 g). These lizards are broadly sympatric in the Kalahari desert. The widely foraging species had significantly higher field metabolic rates (800 vs. 544 J/d, as measured with doubly labeled water), feeding rates (metabolizable energy of 1165 vs. 739 J/d), production rates (365 vs. 195 J/d) and water influx rates (0.285 vs. 0.156 mL/d). Measurements were made before the reproductive season began; there were no significant differences in these measures between sexes within either species. Resting metabolic rates (measured as O/sub 2/ consumed) were similar at 37/sup 0/C (0.240 vs. 0.252 mL g/sup -1/ H/sup -1/) and 26/sup 0/ (0.094 vs. 0.103 mL g/sup -1/ h/sup -1/), the field active and nocturnal burrow temperatures respectively, of both species. Field metabolic rates, on a 24-h basis, were 3.1 x resting in E. lugubris and 2.2 x resting in E. lineoocellata. Energy expenditures during the activity period were 12.0 x resting in the wide forager and 2.8 x resting in the sit-and-wait predator. Foraging efficiency (metabolizable energy gained while foraging/total energy spent while foraging) was higher in the wide forager (2.0 than in the sit-and-wait predator. The wide forager grew nearly twice as fast as did the sit-and-wait predator during this study. On an annual basis, variation in food availability or differences in predation rate may alter the relative fitness of these foraging modes.
- Research Organization:
- Univ. Of California, Los Angeles
- DOE Contract Number:
- AC03-76SF00012
- OSTI ID:
- 6896467
- Journal Information:
- Ecology; (United States), Vol. 65:2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
LIZARDS
ENERGY BUDGETS
FEEDING
METABOLISM
ANIMAL GROWTH
COST BENEFIT ANALYSIS
DESERTS
DOUBLE LABELLING
ENERGY CONVERSION
FOOD
INTAKE
REPRODUCTION
WATER
ANIMALS
ARID LANDS
CONVERSION
GROWTH
HYDROGEN COMPOUNDS
LABELLING
OXYGEN COMPOUNDS
REPTILES
VERTEBRATES
510100* - Environment
Terrestrial- Basic Studies- (-1989)
550500 - Metabolism