Resource exploitation by shorebirds in marine environments is influenced to a large degree by the tidal cycle. The periodicity of the tides dictates where and when shorebirds will feed (Connors et al. 1981). Some shorebirds that find their prey by touch feed whenever tidal conditions permit, independent of ambient light levels (Goss-Custard 1969).
In this study, I counted shorebirds of nine species in two plots of equal sizes. All censuses were conducted within a fixed interval of tidal height during both the flood and ebb tides. With this important abiotic variable held constant, I addressed three hypotheses:
(1) Shorebird numbers in winter are constant in one location at a fixed tidal height.
(2) Shorebird numbers in one location do not change in the same tidal height interval on the ebb and flood tides.
(3) Shorebird species are distributed in each plot equally (numbers of each species and total biomass of shorebirds within each plot are equal).