Fat birds have better sex, study says Ornithologists have long wondered why some birds carry a little more fat than they need for their epic migrations. After […]

Ornithologists have long wondered why some birds carry a little more fat than they need for their epic migrations. After all, why make a journey over thousands of miles even more arduous than it already is?

Now a new study suggests that it may all boil down to reproduction.

“Individuals that arrive on the breeding grounds with surplus fat stores are likely to experience enhanced reproductive performance, regardless of sex” The i newsletter cut through the noise Email address is invalid Email address is invalid Thank you for subscribing! Sorry, there was a problem with your subscription.

Fattening up gives female birds “a reproductive boost” when they reach their breeding grounds by giving them more energy to produce eggs, finds the research by SUNY and William Smith colleges in New York state.

“Individuals that arrive on the breeding grounds with surplus fat stores are likely to experience enhanced reproductive performance, regardless of sex,” said Frank Moore, of the University of Southern Mississippi.

Extra fat is form of insurance

He was not involved in the research but first suggested the extra fat may be connected to sex together with an alternative theory – that it might be a form of insurance on the way, for example to ensure the bird has enough food if it is blown off course by a storm.

The researchers studied information about the weight and condition of 12 different species of warblers as they arrived at a bird-ringing station on the south shore of Lake Ontario over a period of 14 years.

Some of these warblers fly from as far south as Argentina to breed in Canada. After the breeding season, blackpoll warblers can fly from the West coast of Canada to the Atlantic coast, then across the ocean to Brazil.

The research, published in the journal The Auk: Ornithological Advances, found the patterns drawn from the data remarkably similar across the 12 species analysed.