| Summary: | In owls and birds of prey male and female have distinctive roles in parental care. Our knowledge about these roles mostly concerns the pre-fledging period, because in the post-fledging period fledglings move about and are thus harder to locate and follow. The great grey owl (Strix nebulosa) is expanding its range in Norway, providing a unique opportunity to study the post-fledglings period, as the resilience of this owl towards disturbances is high. Four adult great grey owls from four different pairs, two males and two females, were equipped with a tail-mounted radio-transmitter that allowed me to distinguish between the parents at prey deliveries and to help locate the fledglings. Field observations were carried out between 21 June and 27 July in the southeastern part of Norway (61°N, 12°E). Most prey items were delivered in the hour blocks of 07.00-10.00 and 18.00-21.00. The male delivered more prey items than the female, 62 and 19 respectively. Of prey captured by the male, fledglings received 59 and the female 2. The probability that the female rather than the male had captured a prey increased with increasing brood size. The female was present in 57% of the cases when an observer approached the brood. The probability of the female being present decreased throughout the season and with fledgling age. Female level of aggressiveness decreased with fledgling age. The female performed distraction display in 75% of the cases where an observer approached. The maximum distance I recorded between a fledgling and the nest it had fledged from was 2791 m. This distance increased with increasing fledgling age. Movement per day for fledglings ranged from 0 m to 602 m, with a mean of 141 m, and increased with increasing fledgling age. The distance between siblings ranged from 0 m to 136 m, with a mean of 28 m, and was independent of fledgling age. The fledglings perched higher with increasing age. All of the 11 fledglings I observed survived throughout the observation period. In the great grey owl, parental care in the ...
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