Shorebird avoidance of nearshore feeding and roosting areas at night correlates with presence of a nocturnal avian predator
2006
Shepard, Marnie L., | Dekinga, Anne, | Goeij, Petra de, | Gill, Robert E. Jr., | Piersma, Theunis, | Ruthrauff, Daniel, | Tibbitts, Lee,
We here report two anecdotes about avian interactions relevant to the interpretation of differences in shorebirdhabitat use between day and night. Several studies have reported that shorebirds avoid feeding and roostingalong nearshore areas at night yet commonly use these sites during daytime. This suggests that nighttimeavoidance of nearshore places is a response to increased danger of predation. When mist-netting during autumn2005 on nearshore intertidal habitats along South Spit, Egegik Bay (Alaska Peninsula), Alaska, we discoveredthat shorebirds that occurred there in large numbers during daytime low tides and roosted there during daytimehigh tides (especially Dunlin Calidris alpina, Rock Sandpipers Calidris ptilocnemis, Black-bellied PloverPluvialis squatarola, and Surfbirds Aphriza virgata), were absent at night. Their avoidance of the area correlatedwith Short-eared Owls Asio flammeus concurrently hunting over the beach and adjacent intertidal habitats.Spotlighting over nearby expansive intertidal mudflats confirmed that the same suite of species continued toforage or roost nearby at night. To bring the story full circle, the morning following one mist-netting effort wefound a Short-eared Owl on the beach that had been killed earlier by a Gyrfalcon Falco rusticolus. In the owl’sstomach were remains of a freshly devoured Dunlin.
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