Zwarts L. (1985) The winter exploitation of Fiddler Crabs Uca tangeri by waders in Guinea-Bissau. ARDEA 73 (1): 3-12

The fiddler crab Uca tangeri is the main prey for several waders feeding on the intertidal flats of Guinea-Bissau (Fig. 3, Table 1).The size-selection is different among these species (Fig. 7). The lower acceptance threshold can be explained with the optimal foraging model of size selection. The handling time increases with prey size (Fig. 5), but the weight increase is more (Fig. 2). Therefore smaller prey is less profitable (Fig. 6) and is ignored if the feeding rate (and thus rejection threshold) rises (Table 2). For bird species taking Uca out of their burrows (Sacred Ibis; Curlew; Whimbrel on ebb and flood) the upper limit is set by the decreasing accessibility (Fig. 4). The width of the gape is a limiting factor too (Fig. 8). Whimbrel is the main bird predator. The prey risk per size class was calculated (Fig. 9). Most species prey upon the small Uca, but since this size is also the commonest, the prey risk increases with size. Only 5% of the Uca is taken out of its burrow. Most are caught when present on the surface to feed or display.