Demography of Northern goshawks in northern Arizona, 1991-1996

Abstract

We studied 282 nesting attempts on 107 territories of Northern Goshawks (Accipiter gentilis) on the Kaibab Plateau in northern Arizona from 1991-1996.Mark-recapture methods were used to estimate recruitment, turnover of adults on territories, fidelity to territories by adults, and apparent annual survival of breeding adults.Territories were regularly spaced at a mean nearest-neighbor distance of 3.9 km.Annual proportion of pairs breeding and recapture rates were high in 1991-1993, sharply declined in 1994, and partially recovered in 1995-1996.Average annual turnover of breeding goshawks was 42% for males and 25% for females.Breeding males stayed on their territories from one breeding year to the next in 97% of cases and females in 95% of cases.Of 64 capture-recapture models evaluated in program SURGE, the model with the lowest AIC {Phi s , P t } showed that, while survival differed between genders, it was constant for both genders over years.Probability of recapturing a goshawk varied with time (0.15 in 1994; 0.66 in 1992) but not with gender; recaptures were lowest in years when few of the territorial goshawks nested and highest when the majority of pairs nested.