Relocated birds don’t sleep well

When managers try to move a species to a new environment, many of the animals often die soon after being released. Now scientists have found one possible reason for the high failure rate. According to a study in Biology Letters, birds don’t get enough sleep when they’re in an unfamiliar place.

The team moved 10 house sparrows from city parks to rural areas in Ecuador and followed their movements with radiotransmitters. Compared to sparrows in natural populations, the relocated sparrows went to sleep 24 minutes later. They also left their roosts 13 minutes earlier and got an average of about 5 percent less rest. The introduced birds often roosted in houses and barns instead of trees, and they didn’t sing much before bed.

The birds may be racking up sleep debt at the time when they need rest the most, the researchers say. To adapt to a new environment, the animals have to learn where food and rest sites are located. Dealing with those challenges “should require an extended and improved — rather than a reduced and disturbed — amount of rest and sleep,” the authors write. The animals’ lack of rest could explain why they fail to thrive in new places. Roberta Kwok | 30 July 2013

Source: Henry, P.-Y. et al. 2013. Birds introduced in new areas show rest disorders. Biology Letters doi: 10.1098/rsbl.2013.0463.

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