Snowy Owl (Bubo scandeacus)
Its most important food items are lemmings, which may constitute the entire diet when plentiful, although other members of the vole family are also eaten, too. Since these rodents exhibit cycles of abundance with a boom every 3-4 years followed by a crash, the fortunes and abundance of Snowy Owls tend to follow along with them. In good lemming years a pair can find enough food in a home range of between 1 and 4 km² in extent, whereas in less favourable years that increases to 8-10km², and breeding activity may be greatly reduced. Outside the breeding season the Snowy Owl may add birds to its diet, sometimes snatching them from the water surface, which is highly unusual for an owl. It will also snare them in aerial pursuit, showing a remarkable and unexpected turn of speed and manoeuvrability.
The Snowy Owl catches rodents primarily by watching the ground from some sort of prominence such as a rock or ridge, and then flying out to get them. If it is successful, it does not do what most owls do, which is to take the food to a hidden place for private consumption, and eat it piecemeal. Instead the Snowy Owl eats its prey on the spot, or nearby in the open, usually gulping it down whole, although if it has a full stomach it will pick at the corpse like a child unenthusiastically eating greens.
Pairs are usually formed just for a season because of the Snowy Owl’s unpredictable lifestyle on the lemming train – the owls not only follow the lemmings’ lead individually in the winter, causing pairs to split up, but the males, which are smaller than the females, tend to move further away from the breeding areas to retreat from the Arctic winter.
Prior to breeding the male may take to the skies with a spectacular display-flight, in which the wings are held up in an exaggerated upstroke, causing the bird to drop down, and then swept equally far down, to produce renewed lift and, overall, and undulating flight. Later, as the pair-bond is formed, the male brings food to the female, as is the case with most owls. He does, though, make his presentation in style, dropping the lemming down while holding his wings up by the carpal joints as if they were hanging from a washing line, and bowing his head forward. This posture is known as the Angel Display.