Ferruginous hawks buteo regalis alter parental behaviours in response to approaching storms

Abstract

Heavy and frequent rain, low temperatures, and strong winds may decrease adult foraging time, cause thermoregulatory stress on nestlings, and lead to nest damage or destruction, all of which can negatively affect breeding success. However, certain parental behaviours can mitigate these potentially negative effects of inclement weather. We examined how parents could mitigate these negative weather effects by adjusting three behaviours— nest attendance, prey deliveries, and nest maintenance— before, during, and after storms at 11 nests of the at-risk Ferruginous Hawk (Buteo regalis) in Canada. Female adults spent an increasing amount of time on the nest as wind speed increased. Similar numbers of prey were delivered before and after storms, suggesting that Ferruginous Hawks do not compensate for lost foraging time. They appeared to demonstrate an ability to detect approaching storms, possibly by responding to falling barometric pressure cues, and may have mitigated the risk of nest damage by increasing their nest maintenance behaviours. Our study is among the first to observe storm preparation behaviour, and indicates that some raptorial birds have the ability to alter nesting behaviour in response to approaching inclement weather.