Estimating nest site fidelity of adult female black brant with multi–state modeling and geographic information systems

Nest site fidelity of adult female black brant breeding at the Tutakoke River, Alaska was evaluated from 1987 to 1993 by recording nest locations of brant marked (approx. 1500) with individually coded tarsal tags. We used two approaches to study fidelity. First, we examined fidelity to four geographic strata within the Tutakoke River colony. For our second analysis approach, we used ARC/INFO to map and measure distances between successive nesting attempts and then estimated the probability of fidelity to within 200 m of the previous nest site. We used program MSSURVIV to estimate movement probabilities and to test hypotheses about fidelity. Both of our analysis approaches indicate that female black brant exhibit a high (>0.72) probability of fidelity to previous nest sites. Our estimates of fidelity were not biased by the confounding of detection, survival and movement probabilities that have plagued previous studies of fidelity.