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RESEARCH PRODUCT

Life span, dispersal and age of nesting Great Grey Owls (Strix nebulosa lapponica) in Sweden.

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description

3,073 Great Grey Owls were banded in Sweden in 1955–2012. 416 were controlled at least once (54.6%) or recovered dead (45.4%). Three birds banded as nestlings were recovered in their 17th calendar year. Most birds were recovered during first year of life. Only 4 females were controlled breeding as 2CY birds. 91.3% of birds controlled as first time breeders were at least 4CY. Birds banded as nestlings and recovered dead between September and July moved 100.8 km (mean) with a median distance of 64 km. Juveniles controlled alive moved 45.9 km (mean) with a median distance of 23 km during first year of life. Maximum natal dispersal was 650 km. Median natal dispersal for females was 40 km, between 7 km and 115 km depending on longevity from hatching to control. Females at ages 2CY, 5CY, 8CY and 11CY had the lowest median natal dispersals. Median secondary dispersal distances (from one nest to a later nestsite) for females lay between 0 km and 9 km. For males both mean and median secondary dispersal distances were less than 3 km.