Get your own 24-hour pest controllers
[The Namibian – 15 April 2010]

Three Barn Owl chicks were removed from their nest on a farm a few weeks after the first chick hatched. Because Barn Owls have staggered clutches, the youngest of the three chicks was received at NARREC at 10 days old whilst the oldest chick was close to three weeks. These three chicks together with the female parent bird would have consumed about 25 kilograms of food in their 6-week nestling period. This translates into around 1000 medium-size mice.

Although Barn Owls can breed all year round, their peak-breeding season is in late summer to autumn. Barn Owls choose natural or man-made spaces that provide a cave like space. For this reason they often use roofs of buildings or spaces in chimneys. They do not build a nest bit simply scrape the ground to create a slight hollow or flattened space.

Barn Owl pairs become very vocal at the start of their breeding season. The most common calls are unmistakable, long loud hissing screeches. Where Barn Owls are active people will hear the screeches of the pre-breeding owl pairs. But it is usually only when the chicks reach the age of two to three weeks old and are chatting to the parent birds that people really react negatively to the nest and remove the owls. Barn owl chicks’ chatter is in the form of loud hissing and three or more chicks hissing at various times through the night can be quite an aural event.

Barn Owls are sedentary and prefer to use the same nest space for years. Although often specializing in catching rodents, they also prey on insects, bats and small birds and can patrol an area up to 10 km from the nest sites. The years that provide plenty of food for owls and are good for breeding generally correspond to pest-plague years for people. It is more than a little likely that the superstition that relates owls to bad luck is directly linked to this phenomenon.

When there are pests people will have problems, crops are eaten in the fields, harvested crops are spoiled in the stores, mice run in the kitchen and roaches are in the cupboards. High pest populations result in spoiled crops, diminished food reserves and at worst disease amongst people. At the same time the high pest populations increase owls’ activities, specifically the size of the egg clutch, the corresponding number of chicks, the number of times that an owl pair will breed in that year and of course the screeches and hisses that will be heard. Over ages this correlation between pest plague years and owl activity has resulted in the owls being superstitiously and mistakenly blamed as bringing bad luck instead of as the true sign of a season potentially bad because of the number of insects, rodents and even small seed-eating birds that can destroy or spoil the food resources.
Every year, as winter approaches NARREC receives baby owls, usually removed from nests sites in roofs and chimneys but sometimes orphaned after parent birds are killed as secondary victims from the use of rat poison. Before this season really gets under way, it would be best to close the chimney top with mesh wire and check all openings into roofs if you don’t want owls to breed there. However, do the calculations on how incredibly useful and efficient and owl pair is at controlling pest species. Provide a nest box for these useful pest controllers and give a resident pair of owls a secure place to continue their natural cycle around the home and farmstead. Place a nest box where there are no owls and maybe entice a pair to move into your area.

For more information on owls and owl nest boxes contact NARREC.

Liz Komen