Time, Energy, and Territoriality of the Anna Hummingbird (Calypte anna)

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Science  27 Aug 1971:
Vol. 173, Issue 3999, pp. 818-821
DOI: 10.1126/science.173.3999.818


The male Anna Hummingbird accommodates seasonal changes in energy demands by varying its allocation of time and energy among different activities; total energy expenditures change relatively little. Augmented terrritorial defense during the breeding season is made possible by increased feeding efficiency due to the availability at this time of very nectar-rich flowers.