Long, sexy tails not a drawback for male hummingbirds birds

March 13th, 2009 - 5:09 pm ICT by ANI  

Washington, Mar 13 (ANI): The long tails sported by male birds in the tropics are often considered a distinct disadvantage because they lead to as much as a 50 percent greater energy loss when flying. Now, however, a new study has shown that they exact only a minimal cost in speed or energy.

University of California, Berkeley biologists have found long tails exact leads to a minimal cost in speed or energy at least in hummingbirds.

“We estimate that having a long tail increases a bird’’s daily metabolic costs by 1 to 3 percent, which means the bird has to visit 1 to 3 percent more flowers in its territory,” said Christopher J. Clark, a graduate student in UC Berkeley’’s Department of Integrative Biology.

“Is that a lot? It’’s hard to say, but we argue that it’’s not, especially when compared to the costs of things like molting and migration,” he added.

During the study, Clark outfitted short-tailed Anna’’s hummingbirds (Calypte anna) with long tail feathers from a red-billed streamertail (Trochilus polytmus), giving the hummingbirds two tail feathers that were five times the normal length.

They found that the hummingbirds with enhanced tail feathers suffered only a 3.4 percent drop in their maximum speed. This corresponded to an 11 percent increase in energy needed to fly at high speeds.

For moderate and low speeds the speeds at which hummingbirds typically flit from flower to flower and hover the long-tailed birds expended considerably less extra energy.

“I think that in most birds with long tails, the long tail is not costly,” said Clark.

“The energetic costs of a long tail are not high, but it remains to be seen if there are any benefits of a long tail, other than the indirect benefit of helping to pass on one’’s genes,” he added.

The study is published in Proceedings of the Royal Society. (ANI)

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