Factors influencing the eastern curlew's distribution and choice of foraging sites among tidal flats of Moreton Bay, South eastern Queensland

Abstract

The use of feeding habitat by eastern curlews in Moreton Bay was examined by means of quantitative density assessment at 26 sites from 13 locations. The sites were chosen to encompass variation in width (area) of tidal flat, seagrass density, and substratum type. Each site was visited four times: during each of a neap and a spring low tide, in January and February 1992. The total curlew count per site was strongly positively correlated with the width of the tidal flat, and had little or no relationship with seagrass density, substratum type or tidal phase. Wide flats also showed more variation than narrow flats in total curlew numbers. Curlew density, measured by the number of birds within 100 m of each side of the water's edge, was also greater on wide tidal flats, showed little relationship to seagrass density or substratum type, but was higher during neap low tides than spring lows. The data suggest that curlews choose soft-sediment intertidal feeding sites on the basis of potential foraging area, and may be particularly sensitive to the lower and infra-littoral areas. A better understanding of foraging site selection by the eastern curlew requires information on site fidelity, feeding success in relation to tidal zonation, diet and the influence of social interactions.