Abstract: Dynamics in distribution and availability of benthic invertebrates as prey items for shorebirds along a coastal beach in Ghana

Jones Kpakpa Quartey1, 2, Alfred Ali Nuoh2 & Yaa Ntiamoa-Baidu1, 2

1Department of Animal Biology and Conservation Science, University of Ghana, Legon, Accra, Ghana.

2Centre for African Wetlands, University of Ghana, Legon, Accra, Ghana

The choice of non-breeding sites for migratory birds depend on the quality of the habitat measured by disturbance levels, predatory risk, suitable environmental and climatic conditions amongst others, but more importantly, availability of food. Esiama Beach is a stretch of sandy shore between the Amanzure and Ankobra estuaries in the Western Region of Ghana that supports internationally significant populations of shorebirds. We investigated the temporal and spatial distribution and availability of prey items for shorebirds with particular reference to the sanderling, to provide a better understanding of the foraging behaviour of the species. Benthos samples were taken with a 14.9cm corer to a depth of 10cm on a monthly basis for a period of 17 months from September 2014 to January 2016 at 500m interval along 13km of beach. The sediments were washed on-site through a 1mm mesh sieve and invertebrates collected and fixed in 70% ethanol for identification and morphometric measurements in the laboratory. Ten invertebrate species were recorded with the surf clam Donax pulchellus accounting for 88% of all invertebrates recorded, followed by Amphipods (6.4%) and Polychaetes (4.5%). Close to 99% of D. pulchellus recorded were at depths under 3cm below the sand surface, thus available to sanderlings. Spatially, most invertebrate species were observed within the intertidal zone. The surf clam was distributed mainly between the intertidal and low tide zones while amphipods were the most abundant in the high tide zone. New recruits of Donax were observed between October and March, the period in which sanderlings were present at the site. There was a significant relationship (p<0.05) between number of sanderlings observed feeding at different areas on the beach and densities of Donax. This could explain the observed seasonal distribution patterns of shorebirds observed at the Esiama Beach.

Keywords: Benthos, invertebrates, prey items, sanderling, Donax pulchellus, Esiama

Corresponding author:  ynbaidu@ug.edu.gh

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