MEPS 254:151-162 (2003)  -  doi:10.3354/meps254151

Depletion of benthic invertebrates by bar-tailed godwits Limosa lapponica in a subtropical estuary

Yuri Zharikov1,2,*, Gregory A. Skilleter1

1Marine and Estuarine Ecology Unit, Department of Zoology and Entomology, University of Queensland, Brisbane, Queensland 4072, Australia
2Present address: Centre for Wildlife Ecology, Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada

ABSTRACT: This study (1) investigated functional (capture rate, foraging success) and numerical (density) responses of bar-tailed godwits Limosa lapponica to an experimental decrease in densities of their prey, and (2) estimated seasonal depletion of the stock of their main prey, the mictyrid crab Mictyris longicarpus, in a subtropical estuary. It was predicted that if intake rates of the godwits are in the vicinity of the gradient section of a functional response curve, i.e. are directly determined by prey density, they will respond rapidly to experimental reduction in the density of their prey. Bar-tailed godwits did respond rapidly, both functionally and numerically, to a decrease in the density of M. longicarpus, indicating that their intake rate was limited by food availability. The estimated seasonal depletion of the stocks of Mictyris by the godwits was 88% of the initial standing stock. Despite the virtual disappearance of Mictyris from sediment samples through the course of a non-breeding season, local densities of godwits did not change between October and March, implying that adequate rates of intake could be maintained throughout their residence period.


KEY WORDS: Bar-tailed godwit · Limosa lapponica · Mictyris longicarpus · Prey density manipulation · Prey depletion · Subtropics


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