Duelling and Nest Failures in Southern Boobooks Ninox novaeseelandiae

Abstract

Male Southern Boobooks Ninox novaeseelandiae Duelled with each other on territorial borders, often close to a neighbour’s nest that had been placed against the border. Nest failure increased with Duelling during two periods: 1996–97 and 2004–05, the last increase linked to a new road cut through bushland of five Boobook territories. Three territories were abandoned, leaving two expanded territories over the same area. It is not clear why Duelling males did not break off Duels and forage for their incubating, food-begging mates. We suggest that males may compete for quality females by maintaining borders around important food sources, tree-roosts, and nest-hollows inside quality territories.