Factors influencing nest attendance and time-activity budgets of peregrinefalcons in interior Alaska

An essential prerequisite to examining the impacts of anthropogenic disturb ance on avian nesting activities is understanding the intrinsic and extrins ic factors that influence the birds' allocation of time to breeding behavio rs. We examined factors influencing nest attendance and time-activity budge ts of peregrine falcons (Falco peregrinus anatum) breeding along the Tanana River in Alaska in 1995, 1996, and 1997. First, as is typical of most bird species with nidicolous young and biparental care, females attended the ne st more than males and, as the nesting cycle progressed, female attendance decreased to levels similar to those of males. Second, nest area attendance followed a circadian rhythm; parents attended the nest area less during ea rly morning and late evening, which are prime hunting periods, than during late morning. Finally, although females typically performed most of the inc ubating, the division of labor between males and females during incubation differed among pairs. Higher attendance in the nest area by females during incubation appeared to be associated with more young fledged among successf ul pairs.