Perceived risks and rewards of foraging sites strongly affect density and condition of non‐breeding Hudsonian Godwits

Abstract

Patchily distributed resources require individuals to balance risks and rewards associated with foraging sites that vary widely in quality, as determined by factors such as food availability, disturbance rates and predation risk. These trade‐offs may be especially acute for migratory species during the non‐breeding season when they must access high‐quality resources to recover from and prepare for migration. We assessed how density and body condition of non‐breeding Hudsonian Godwits Limosa haemastica, acting as proxies for foraging site quality, were related to foraging success, availability of intertidal foraging habitat, landscape and bay characteristics, human disturbances and predation risk at 42 intertidal mudflats in southern Chile. Godwit density and body condition increased with availability of foraging habitat and foraging success, except on mudflats where individuals were more alert and agitated (i.e. higher scanning rates and more displacement flights). In contrast, body condition and density of foraging Godwits were lower at sites with high levels of perceived disturbance. Our findings suggest that the non‐lethal effects of disturbances (i.e. perceived risks) may affect behaviour (e.g. scanning rates and displacement flights) in ways that can compromise refuelling rates, body condition and performance across seasons. Thus, efforts to reduce disturbances to individuals foraging on tidal mudflats may be important to conserve migratory shorebirds, a guild undergoing severe population declines.