Autumn 2009 Long-eared Owls

Finally I have time to concentrate on the owl photos taken during last autumn in Hanko Bird Observatory. I'll start with Long-eared Owls (Asio otus) . The most reliable ageing criterion is the pattern of secondaries. Here's a brief summary with photos of different autumn age classes.

1st cy female (above) and 1st cy male (below).
Juvenile secondaries are all uniform and they
show 5-6 thin black bars.


2nd cy female.
2nd cy birds show secondaries with two age
classes. The moulted adult-type
secondaries are darker and they show only 3-4
broad black bars while the unmoulted juvenile
secondaries are worn and lighter with juvenile
barring.



Adult female (above) and adult male (below).
Adult birds (older than 2nd cy) show adult-type
secondaries of two generations.