Bird Migration: The Search For Fruit-ful Rest Stops

Even birds taking long trips during migrating seasons need to stop and stretch their wings. So how do they decide where and when it is best to take a break and fuel up? Researchers from the University of Maine recently discovered that migrating birds tend to pull over in areas that have dense vegetation in order to hide from their predators.

According to a news release, in order to better understand how the birds decide where are the safest, yet most plentiful, locations, Jennifer McCabe and Brian Olsen, from the University of Maine's Climate Change Institute, spent the last two years capturing migrating birds during the fall.

"Hawks, primarily falcons, are found in large numbers on Maine's coastal islands during fall migration, keying in on the songbirds on migration stopover in the region. McCabe and Olsen's manuscript does a brilliant job of assessing the balance between risking predation and fueling the energy demands for migration at six bird-banding stations along the Maine coast," Glen Mittelhauser, from the Maine Natural History Museum, said in the release.

The researchers monitored six sites along the coast of Maine, where the birds encountered one of two situations. Either the birds quickly found shelter and sufficient food--or they had to venture into the open to find more sources of sustenance.

In total, the researchers captured almost 10,000 birds belonging to 28 species. From their study, they concluded that if the birds were faced with a tradeoff they moved on, in search of a safer rest stop. On the other hand, if a bird faced a longer migration, it might be tempted to take risks in open areas, in exchange for high-energy fruits.

"The neatest aspect of the study was that we used the entire migratory community to look at tradeoffs between foraging and predator avoidance similarly to behavioral research on single species, and we found similar results at the community scale as single species studies did," McCabe explained in the release.

The researchers further noted that the most desirable forests were those with brush, which is considered to be tall grasses, shrubs or bushes growing beneath tall trees. In order to better protecting migrating species, the researchers urge that wildlife managers monitor these habitats.

Their findings were recently published in The Auk: Ornithological Advances.

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