Hawk Owl (Surnia ulula)
To hunt it practises the “perch and pounce” method, observing prey from an elevated vantage point and gliding down to grab it. Long term studies have come up with an interesting insight into the details of this: apparently a bird must change vantage points 13.5 times for each successful capture, using five different perches in all. Low perches are also more profitable than high perches, all of which suggests that the smaller the distance between prey and predator, the high the capture rate.
Being vole specialists, the Hawk Owl’s fortunes and movements are determined by the availability of these small mammals, which have a 3-4 year cycle of abundance. In good vole years the birds may breed further south than usual, whereas in poor years they may not breed at all. As a result, the Hawk Owl is one of Europe’s few truly nomadic birds, with individuals moving around in any direction in search of food. Normally they neither maintain territories or pair bonds beyond one season.
Hawk Owls rely for breeding habitat on the juxtaposition of forests and open country, which provide nest holes and food respectively. Their idea of a perfect location is a large bog surrounded by forest, and they also reach out into the thinly wooded southern limit of the tundra, to the south of the range of the Snowy Owl.