Piping Plovers make decisions regarding dispersal based on personal and public information in a variable coastal ecosystem

An increasing number of studies have revealed that public information influences dispersal decisions in a wide variety of species. However, few empirical studies have explored the effect of environmental predictability on the use of public information. We applied a model-selection approach to data gathered from 1998 to 2006 in five eastern Canada provinces to determine the factors influencing breeding dispersal distances of Piping Plovers (Charadrius melodus melodus), a species that encounters substantial interannual changes in habitat quality. We examined the following hypotheses: (1) individuals that are unsuccessful breeders disperse greater distances than individuals that breed successfully and (2) dispersal distances of failed breeders are negatively correlated with the reproductive success of locally breeding conspecifics. We found that mean dispersal distance was greater for plovers that did not breed successfully the previous year (x1 = 17.8 ± 27.4 (SD) km, =15) than for those that were successful (x = 5.8 ± 26.4 km, N = 71). Failed breeders whose neighbors produced no fledged young dispersed over distances 34.8 times greater than those whose neighbors produced four fledglings. Our results show that public information is used in habitats whose environmental predictability is lower than predicted by theoretical studies. Thus, dispersal appears to be triggered by a combination of failure to hatch at least one egg, and the failure of neighboring pairs to produce fledglings. Individuals therefore appear to preferentially return to sites where breeding success is high. This may partly explain why Piping Plovers use only a fraction of the suitable breeding habitat within their geographic range. Consequently, although suitable habitat is present elsewhere within the breeding range, the loss of traditional nesting sites is likely to significantly impact productivity of this endangered species.