Determinants of Between-Season Site, Territory, and Mate Fidelity in Hooded Warblers (Wilsonia Citrina)

Abstract

Abstract We examined nestling paternity, fate of nests, and prior experimental manipulations in Hooded Warblers (Wilsonia citrina) to test the hypothesis that those factors influenced the warblers' fidelity to their previous breeding site (general breeding area), territory (specific nesting and feeding area within general breeding area), and mate the following year. Field re-search was conducted at Hemlock Hill Biological Research Area in northwestern Pennsylvania from 1991 to 1998. Hooded Warblers returned to Hemlock Hill at an average annual rate of 47% over seven years. Significantly more males than females returned in 1992 and 1995, but overall difference between male and female return rates was not significant. Frequency of males returning to their former territory (58%) was greater than frequency of females returning to their former territory (29%). When mates from the previous year returned, remated pairs (n = 13) occupied their former territory more often than they occupied a new territory. Average number of young fledged per nest tended (P = 0.06) to be greater for females that returned to Hemlock Hill than for females that did not return. There was also a tendency (P = 0.09) for females that returned to the breeding site to have more nests with extrapair young than those that did not return. Territory fidelity and mate fidelity for both males and females were not related to prior nest fate or paternity of young. During those years, we conducted two relatively long-lasting experimental manipulations: vegetation removal from nest sites and radiotagging. Those experimental manipulations did not significantly affect future selection of breeding site, territory, or mate. Thus, whereas male Hooded Warblers demonstrated greater territory fidelity than females, only females were possibly affected by factors that we examined from the previous year, specifically extrapair fertilization and prior reproductive success or failure.