Jones K. Quartey1,2, Alfred A. Nuoh1 & Yaa & Ntiamoa-Baidu1,2
1Centre for African Wetlands, University of Ghana, Legon, Accra. sherver21@yahoo.com
2Department of Animal Biology and Conservation Science, University of Ghana. P.O. Box LG 67, Legon, Accra.
The abundance of sanderling along the Esiama beach in Ghana has been shown to be correlated to the density of the main prey Donax pulchellus. We studied the feeding strategies, foraging rates and activity time budgets of sanderling on the 13 km Esiama beach in relation to the distribution, abundance and availability of D. pulchellus. Data on sanderling feeding activities were recorded through direct observations and captive experiments, while prey availability was studied through benthic sampling. Donax pulchellus constituted about 96% of all invertebrates in benthic samples and were distributed mostly in the area between the high and low water marks. About 94% of D. pulchellus in the area occurred within the top 3 cm depth of sand and therefore available to sanderlings. Sanderlings spent on average 60% of their time foraging; this varied from 58% to 84% depending on numbers of sanderling on the beach, prey densities and stage in the migration cycle. Sanderlings used different parts of the beach at different times, likely in response to prey distribution in order to obtain optimum prey intake. They employed more visual feeding methods such as pecking when prey densities were high, and more tactile methods such as probing and sewing when prey densities were lower. For example, sanderlings pecked more (31 pecks/min) and probed less 7.3 seconds/min in September when prey density was high but pecked less (10 pecks/min) and probed more (15 seconds/min) in November when prey densities were lower. The intake rates of captive sanderlings also varied between 1-3 D. pulchellus individuals/min depending on the size of prey. The feeding strategies employed by sanderlings may be used to explain distribution and abundance of invertebrates along the Esiama beach.
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