Breeding settlement and dispersal in a northern population of American kestrels.

Birds should choose breeding sites that will maximize fitness. In so doing, they must evaluate a host of environmental and ecological cues that signal the costs and benefits that may be realized at a particular breeding site. This evaluation begins at a broad spatial scale, such as when deciding whether to undergo large among-year movements, and continues to the finest scale which involves an evaluation of the specific attributes of potential nest sites. Furthermore, parents should invest in reproduction to maximize their fitness according to the conditions existing at their breeding site. I evaluated the influence of prey abundance and structural features of the nest and surrounding habitat on nest-site selection, and reproductive investment and success of a population of American kestrels (Falco sparverius) in north-central Saskatchewan. I also evaluated the influence of the perception of the risk of nest predation on these variables by experimentally manipulating auditory and visual cues of the presence of a common nest predator near nest sites. Finally, I utilized stable hydrogen isotope ratios in feathers to examine among-year settlement decisions (breeding dispersal) and conducted preliminary analyses to ascertain the mechanisms responsible for the observed variation in hydrogen-isotope values in the feathers of kestrels ...My study showed that further examination of the processes affecting individual physiologies during breeding may lead to a better understanding of deuterium enrichment of raptor feathers. My study also highlights the complexity of the ecology of nest-site selection, suggesting that while food is important for certain aspects of reproduction, interspecific and scale-dependent interactions with landscape features play an important role in nest-site selection and breeding decisions. --P. i-ii.