Vol. 52, 2013

Effect of male provisioning on the parental behavior of female Boreal Owls Aegolius funereus

Markéta Zárybnická* and Jiří Vojar

Faculty of Environmental Sciences, Czech University of Life Sciences Prague, Kamýcká 129, Prague 16521, Czech Republic

Abstract
Background: Sex-specific parental roles of most raptors allow mates to cooperate during breeding; while females incubate and brood, males provide food. If one partner fails in its parental duties, however, sex-specific parental roles can limit the ability of each sex to carry out the role normally performed by its partner. We observed the effect of male food provisioning on female parental care in Boreal Owls Aegolius funereus using cameras at 12 nests in western Finland in 2005. We compared the parental care of eight females in nests with a high male feeding rate (successful nests) with that of the females in four nests with a low or zero male feeding rate (failed nests).
Results: Females brooded more intensively in nests where males provided sufficient food for the family. These females continually stayed with the young until the late brooding stage (18 days after hatching). After completing the brooding period (21 days after hatching), they either no longer visited their nests or began to provide food to their young together with males. Females exposed to a low or zero male feeding rate left their young for long periods without brooding during the early brooding stage (8 days after hatching) and provisioned nestlings at a mean rate of 0.6 ± 0.8 prey items/night. As a consequence, all of these nesting attempts failed. One female that was widowed 21 days after hatching stopped brooding and began food provisioning alone, but only one of six young successfully left the nest. Body masses of females in successful and unsuccessful nests were similar, indicating that females in nests with insufficient provisioning did not markedly suffer from a lack of food.
Conclusions: Female Boreal Owls adjusted their parental care based on the level of parental effort of their mates and the nesting phase. The nesting attempts, in which males did not provide enough food for the family during the early brooding stage, failed. We concluded that bi-parental care in northern populations of Boreal Owls is essential until brooding is completed.

Key words: Parental care; Food provisioning; Sex roles; Sexual conflict; Nest desertion.

*Correspondence: E-mail: zarybnicka.marketa@seznam.cz