Bad Egg

People have built artificial nests for birds with the best of intentions — to provide more breeding spots in degraded forests. But researchers have found that some hawks are less likely to raise chicks successfully in such nests. These man-made structures could act as “ecological traps” for vulnerable species, the team warns.

The study took place in Finland, where clear-cutting has left fewer large trees for hawks to nest in. To compensate, people have fashioned artificial nests out of planks, sticks, and twigs and mounted them on tree branches. Volunteers also have tracked hawk nests in the area for three decades.

The researchers examined the data collected on northern goshawks, common buzzards, and honey buzzards, covering more than 5,000 nests. The first two species bred more successfully in natural than artificial nests, the team reports in Animal Conservation. For example, goshawks raised one or more chicks 91 percent of the time in natural nests but only 87 percent of the time in artificial nests.

Man-made nests are still useful; after all, “lower success is better than no nesting,” the authors write. But they worry that birds that trade natural for artificial nests will face lower odds of producing chicks. Roberta Kwok | 12 March 2013

Source: Bjorklund, H. et al. 2013. Evaluation of artificial nests as a conservation tool for three forest-dwelling raptors. Animal Conservation doi: 10.1111/acv.12028.

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