HABITAT DETERIORATION AND EFFICIENCY OF ANTIPREDATOR STRATEGY IN A MEADOW-BREEDING WADER, TEMMINCKS STINT (CALIDRIS-TEMMINCKII)

Many populations of waders breeding on open shores and shores with sho rt vegetation especially on the Baltic coasts have recently become end angered. The declines have taken place simultaneously with human-induc ed loss and deterioration of habitats due to eutrophication and overgr owth. To Investigate mechanisms by which habitat changes could affect breeding success and ultimately population dynamics, we studied an end angered coastal population of Temminck's stint. We hypothesized that t he rate of nest predation has become higher because the nest defence s trategy (early detection of predator and early departure from the nest ), which originally evolved in open habitats, is less effective on sho res with reduced visibility. As predicted. nests survived better on wi de than on narrow shores. Predation made a major contribution to this trend. although successful and predated nests did not differ in concea lment at a microhabitat scale. The better the visibility from the nest , the longer was the flushing distance, but only in response to alarm calls or behaviour of other species, not when they were absent. Temmin ck's stints seem to obtain information about an approaching predator v isually from sentinels. Therefore, it is essential that there is at le ast moderate visibility around the nest. We conclude that habitat char acteristics - visibility from the nest and sentinel birds - affect the effectiveness of the nest defence strategy of Temminck's stint. These should be taken into account when seeking causes and mechanisms for d eclines of Temminck's stint and other waders of open and shortly veget ated shores.