Snowy Owls (Bubo scandiacus) in Arctica
by Harald Schmidt
They are in Rotterdam Zoo again: the Snowy Owls.
Snowy Owls are impressive animals you will find in many zoos. In 2005 this species had to go from our collection because the Appelman-pheasant house had to make room for the newly built Oewanja restaurant.
When planning the new polar bear enclosure we already considered to reserve some space for snowy owls from the polar region. The snowy owl is a fine example of an animal species that is eminently adapted to its environment in the Arctic tundra.
For quite some time biologists thought that snowy owls were not directly related to other owl species. But thanks to the development of modern techniques we now know that the snowy owl is sharing much DNA with the eagle owl. Although they are quite different in appearance both species have a close family tie. Snowy owls are found around the entire polar circle (Europe, Asia and North America). In winter they migrate to a southern region.
The length of a snowy owl is approx. 53 to 65 cm with a wingspan of 140 cm. Their weight varies from 1,8 to 3 kilogram. Male and female owls of many species look alike, the only difference is that often females are somewhat larger and heavier. The difference between adult female and male snowy owls is more distinct. The females are not only larger than the males but are different in colour as well. The males are almost totally white whereas the females are white with brown bars. This is a breeding behaviour adaptation. Snowy owls often start nesting while the snow on the tundra has only just started melting. The female is breeding, the male has to provide the food. The female with its white-brown plumage is very inconspicuous in the tundra when there are still some snow patches. The female needs this protective colouring because by lack of trees on the tundra she has to lay her eggs in grassy hummocks on the ground. Eggs are laid every other day with an average of 6. Exceptions of a total of 14 eggs are possible.
Hatching starts immediately after the first egg has been laid. Consequently in a snowy owl’s nest you may find eggs and broods of chicks that range widely in age and size!
It is interesting to know that close to the nest of a snowy owl you will often find a nest of a Brant goose. It is common knowledge that snowy owls will fiercely defend their nests from Arctic foxes and Brant geese may benifit from this behaviour. Besides Brant geese are known for their alertness so it may well be that both parties will profit from the nearness of the two nests.
Although snowy owls can catch rather big prey their main food consists of lemmings and voles. Snowy owls need seven to twelve of those small rodents a day to survive. During breeding they need much more prey of course. Snowy owls are able to hunt in daytime as wel as at dusk. In the arctic region there is daylight for almost 24 hours a day. On the arctic tundra lemmings have periodic population booms unfortunately resulting in big population fluctuations. Often the population crashes almost to extinction about every three to four years forcing the snowy owls to set out to southerns areas. In case of serious food shortage many snowy owls do not survive. Some birds are spotted in unexpected places, often southands of miles away from ‘home’. Last winter snowy owls were seen in various places in Europe. In the Netherlands one has been seen on Texel, one of the Frisian Islands, where it attracted a great deal of attention from birdwatchers and photographers. This owl also visited some other Friasian Islands. This winter snowy owls have been seen in Belgium, Scotland and on the Channel Islands as well. Because all these birds were seen in coastal areas it may well be that they are from Canada and Greenland. It is likely that some snowy owls went off-course and when exhausted landed on ships in the Atlantic Ocean to go ashore again in Europe.
In 1964 Rotterdam Zoo received six snowy owls from the Holland America Line. These owls had also landed on a ship when exhausted. Two of those stranded snowy owls have lived in Rotterdam Zoo till 1990 and produced many offspring. At present we have one pair of snowy owls from the collection of Amersfoort Zoo. Although snowy owl chicks are cute we do not intend to breed with the animals. There are quite some snowy owls in zoos and the demand is low and what is more, owls are living to a great age.
Although their enclosure is according to the Biota concept (their habitat) it may take some time for them to settle down. It may look somewhat bare but that is what snowy owls prefer.
photo: Reinettatranslated article Blijdorp Blad 3 - fall 2009