MEPS 406:281-289 (2010)  -  DOI: https://doi.org/10.3354/meps08519

ABSTRACT: Predators may have a series of alternative foraging modes. Under the food resource maximization hypothesis, predators are expected to shift between foraging modes such that they attain the highest intake rate in response to prey availability and constraints varying with environmental conditions. To test this hypothesis, we measured foraging action rate (actions per unit time), capture rate (captures per unit time), and intake rate (amount of energy and nutrients per unit time) for 2 foraging modes, pecking (feeding on epifauna at the sediment surface) and probing (feeding on infauna by inserting the bill into the sediment), in dunlin Calidris alpina on an intertidal sandflat. The birds chose their foraging mode to attain higher feeding success, i.e. individuals that obtained higher capture and intake rates by pecking allocated a higher proportion of foraging effort to pecking, and vice versa. The birds shifted foraging mode from probing to pecking with increased time after emersion. The shift may be related to decreasing efficiency of probing due to increases in the costs of energy and time caused by decreasing sediment penetrability (increasing hardness) with time after emersion. Our in situ study empirically suggests that, while environmental constraints reduce the predators’ foraging mode flexibility, the birds show individual-based appropriate adjustments in their foraging mode to attain a higher intake rate at a given time and patch. This extends the ideal forager model for patch choice into foraging mode choice.

KEY WORDS: Decision making · Feeding ecology · Foraging behavior · Intertidal ecosystems · Shorebirds

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Cite this article as: Kuwae T, Miyoshi E, Sassa S, Watabe Y (2010) Foraging mode shift in varying environmental conditions by dunlin Calidris alpina. Mar Ecol Prog Ser 406:281-289. https://doi.org/10.3354/meps08519 Export citation Share:    Facebook - - linkedIn