Australasian Science: Australia's authority on science since 1938

Where Has All the Roadkill Gone?

By Magdeline Lum

Some birds are evolving shorter wings to help them avoid cars, and the stress of combat training leads to gastrointestinal issues.

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Swallows the world over have slender, streamlined bodies and long, pointed wings, allowing them to hunt and eat insects while flying. They are incredibly efficient at flight and are capable of reaching speeds in the range of 50–65 km/h with great manoeuvrability. Despite their speed and mobility, they do make up a proportion of roadkill each year.

The American cliff swallow (Petrochelidon pyrrhonota) migrates between North and South America. Prof Charles Brown of the University of Tulsa and his wife, Dr Mary Bomberger Brown of the Tern and Plover Conservation Partnership at the University of Nebraska, have studied this migration and associated roadkill carefully. The data they have collected shows that roadkill exerts a selective advantage on swallows with shorter wingspans.

“Evolution is an ongoing process, and all this – roads, SUVs and all – is part of nature or ‘the wild’; they exert selection pressures in a way we don’t usually think about,” Prof Brown says.

The couple travelled the same roads every year for three decades, stopping to collect dead birds. They observed a decrease in mortality of the cliff swallows over this period.

In 1982, 20 dead birds were collected compared with up to four dead birds collected in the past 2 years even though the swallows being studied have nests near major roads, bridges, overpasses and culverts. The...

The full text of this article can be purchased from Informit.