Philopatry, nest-site tenacity, and mate fidelity of Semipalmated Plovers

Philopatry, nest-site tenacity, and mate fidelity were examined in a popula tion of Semipalmated Plovers Charadrius semipalmatus breeding near Churchil l, Manitoba, Canada from 1992 to 1997. Natal philopatry was low (7 of 445 ( 1.57%) hatchlings returned to the study area to breed) and no difference in sex of recruits was detected. Adult males returned at a significantly high er rate (58.9%) than adult females (41.2%). For both sexes, but more strong ly for females, success in the previous year resulted in higher return rate s in the subsequent year. Of pairs that returned, 41.6% divorced. Females t hat divorced or changed mates through death or disappearance of a partner b etween breeding seasons were significantly less site tenacious than females that reunited and also less so than males of any pairing status. Females t hat experienced breeding failure and changed mates in the subsequent breedi ng season moved farther than successful females that changed mates. In only one of four years did reunited pairs nest earlier and have greater hatchin g success than novel pairs. After divorce new mates of females did not diff er significantly in morphological or plumage characteristics from old mates , nor did they possess territories with greater visibility, or territories nearer to water. After divorce new mates of males were significantly smalle r than old mates. Our return rates underestimate survivorship in females be cause both the probability of return and site tenacity of females are stron gly influenced by their previous success.