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9 September 2015 Tradeoffs between predation risk and fruit resources shape habitat use of landbirds during autumn migration
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Abstract
While foraging, animals often trade off between food and safety, reducing feeding in response to increased predation risk. This response, however, may not be a viable option for animals that are energetically compromised. Many single-species studies have shown that hungry animals select habitats within which foraging opportunities are greater even if predation pressures are higher, but it is unclear whether these patterns can be extrapolated to entire communities. Here, we examined the stopover habitat use of 28 frugivorous landbird species along the coast of Maine, USA, during an energetically demanding period of the annual cycle, fall migration. Across 6 stopover sites, we determined whether or not a tradeoff existed between using safe habitat patches (patches with high woody plant stem density) and patches with high food resources (patches with high fruit abundance). Controlling for raptor abundance at a site, landbird migrants were captured at higher rates in sites where no tradeoff existed, suggesting that birds avoided staying in sites where there was a predation risk–foraging tradeoff. At all sites, regardless of the presence or absence of a tradeoff, longer-distance migrants used patches with high food availability more frequently than shorter-distance migrants; patch use by shorter-distance migrants was explained by habitat cover alone. Our findings suggest that, for the Gulf of Maine, birds reduce predation risk at the scale of a stopover site, and differences in habitat selection at finer patch scales are mediated by migration strategy.
Jennifer D. McCabe and Brian J. Olsen "Tradeoffs between predation risk and fruit resources shape habitat use of landbirds during autumn migration," The Auk 132(4), (9 September 2015). https://doi.org/10.1642/AUK-14-213.1
Received: 17 September 2014; Accepted: 1 June 2015; Published: 9 September 2015
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