SUMMARY
Animals must optimize their daily energy budgets, particularly if energy expenditures are as high as they are in flying animals. However, energy budgets of free-ranging tropical animals are poorly known. Newly miniaturized heart rate transmitters enabled this to be addressed this in the small, energetically limited, neotropical bat Molossus molossus. High-resolution 48 h energy budgets showed that this species significantly lowers its metabolism on a daily basis, even though ambient temperatures remain high. Mean roosting heart rate was 144 beats min–1, much lower than expected for a 10 g bat. Low roosting heart rates combined with short nightly foraging times (37 min night–1) resulted in an estimated energy consumption of 4.08 kJ day–1, less than one-quarter of the predicted field metabolic rate. Our results indicate that future research may reveal this as a more common pattern than currently assumed in tropical animals, which may have implications in the context of the effect of even small temperature changes on tropical species.
FOOTNOTES
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FUNDING
Funding for the student field course, including all equipment, was provided by the Max Planck Society and the University of Princeton.
- © 2011.
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