Turnover rate of breeding Cooper’s Hawks in Tucson relative to disturbance

Background/Question/Methods

Cooper’s Hawks can live in urban areas and benefit from the abundance of food (e.g., doves and pigeons), but can suffer from window strikes, electrocution, trichomoniasis, and potentially from disturbance related to people, pets, and traffic.  My objective was to determine the effects that different levels of disturbance have on the turnover rates of breeding Cooper’s Hawks in Tucson, AZ.  I visited 48 nest sites in 2014 where in the previous year, hawks that had been marked with colored leg bands engraved with an alphanumeric code had been present. I classified each nest site as either high or low disturbance, based on the level of traffic noise and number of people present, and determined based on band numbers whether the breeding individuals were the same as in 2013. 

Results/Conclusions

The percentage of nests where either a male or female hawk was replaced was the same in both high and low disturbance areas (6.3%), suggesting that disturbance as I assessed it was not a significant determinant in turnover rates. However, I did not assess what specifically caused the mortality of the hawks that were replaced.  Further studies should investigate whether agents of mortality (e.g., electrocution, window strikes) differ between areas of high and low disturbance.