Owls

Kruger National Park | May 2017

Throughout history people have regarded owls with fascination and awe. There are many superstitions that revolve around owls. In some cultures owls are seen as the “wise old bird” that knows everything, whereas in other cultures owls are associated with death and witchcraft. As owls are generally nocturnal birds they are often considered to be very mysterious.

Owls are widespread throughout the world and are found on all the continents with the exception of Antarctica. There are approximately 200 species of owls in the world and in southern Africa there are 12 species. In the Lebombo Concession we have seen the following species: barn owl (Tyto alba), African scops owl (Otus senegalensis), southern white-faced scops owl (Ptilopsis granti), pearl-spotted owl (Glaucidium perlatum), marsh owl (Asio capensis – rarely seen in the concession), spotted eagle-owl (Bubo africanus) and Verreaux’s eagle-owl (Bubo lacteus). Although we do not see Pel’s fishing owls in the concession they do occur along some of the larger rivers in the Kruger Park.

Owls are very distinctive looking birds that are typified by having an upright stance, a large and broad head, large eyes that are situated in the front of the face and therefore allow for binocular vision, an acute sense of hearing, sharp talons on zygodactyl feet (two toes point forward and two toes face backward), and feathers adapted for silent flight.

Owls are considered to be nocturnal birds of prey and feed predominantly on small mammals such as mice, small birds, insects and other invertebrates. One species of owl in southern Africa, the Pel’s fishing owl (Scotopelia peli), feeds mainly upon fish.

Owls fall under the order Strigiformes and are divided into two main families viz. the Strigidae family and the Tytonidae family.

As they are generally considered nocturnal birds and are therefore mainly active at night they have specific physical modifications that assist them to be able to locate prey and hunt effectively in low light conditions. Most owls have large forward-facing eyes which allow them to have great depth perception. Instead of spherical eyeballs, owls have “eye tubes” that go far back into their skulls. Although they are not able to move their eyes they have adapted to be able to turn their heads almost 270 degrees. This is achieved by having specific bone adaptations (owls have 14 neck vertebrae, compared to 7 in humans) and a supporting vascular network that allows the owls to turn their heads that far without cutting off blood-supply to the brain.

Some owl species have asymmetrically set ear openings (i.e. one ear is higher than the other). In South Africa this is particularly evident in the barn owl. This asymmetrical positioning of the ears on the sides of the head allow for absolute pin-pointing of prey species, even in almost completely dark conditions. Owls use these unique, sensitive ears to locate prey by listening for prey movements in the undergrowth below. When a noise is heard, the owl is able to tell its direction because of the minute time difference in which the sound is perceived in the left and right ear. Most owls have flat faces, with a conspicuous circle of feathers known as the “facial disc”. The feathers making up this disc can be adjusted to sharply focus sounds from varying distances onto the owls’ asymmetrically placed ear cavities. Another adaptation that allow owls to hunt at night is the innate ability to fly almost silently, which allows them to surprise their prey. This ability to fly almost silently is as a result of a velvety or fluffy surface to the feathers and the fact that many of the flight feathers have a comb-like edge. This reduces the sound made by the feathers as they slice through the air and it also allows the owl to fly at slower speeds than most other birds of prey.

Owls catch their prey with powerful feet and sharp talons. Prey is detected either by sight, hearing, or a combination of the two, and is caught by a quick stoop and drop. Owls contribute substantially towards controlling rodents and other potentially problematic animals, and are therefore an ally to landowners, in particular grain farmers. Studies have shown that a single Barn Owl family can eat up to 3 000 mice or rats per year. Owls often swallow their prey whole. After digesting their food, owls regurgitate hard pellets of compressed bones, fur, teeth, feathers and other materials they couldn’t digest. These pellets look like furry balls or sausages and if one dissects the pellet one will often find bones and insect elytra inside.
Many owls have ear-tufts on top of their head. These ear-tufts are formed from feathers that can be raised or dropped flat against the head, and although they are known as ear-tufts they have nothing to do with the ears, but rather aid the owl by camouflaging them better and allowing them to look more like broken branches. They are also used to visually communicate with others and to express emotions.

Owls have the unusual ability among birds to be able to bring food items up to their beaks with their feet. Other birds in southern Africa that can also do this include parrots and kestrels.

Most owls nest in holes in trees or on rock ledges, although barn owls also sometimes make use of human habitations and buildings such as barns (hence the name). Most owl eggs are white in colour and are unusually round in shape. The white coloration of the eggs assist the adults to see them in the dark.
Some of the major threats facing owls include poisoning (particularly secondary poisoning, where poison is put down to eradicate rodents. Unfortunately, as apex predators, owls feed on quite a few rodents and if the rodent is not immediately killed by the poison and the owl catches and feeds upon it the poison can build up in the owl’s body to the point where the owl is inadvertently killed), collisions with vehicles and with fences, habitat destruction and deliberate killing by humans. In Africa there is a traditional belief that owls are bad luck and are still considered agents for witches or sorcerers. Many people still follow this belief and will kill, chase or maim owls out of misguided fear. Owls are also prized as ingredients in traditional medicine because of their perceived wisdom, hunting skills and remarkable eyesight.

All owls are listed in Appendix II of the international CITES treaty (the Convention on Illegal Trade in Endangered Species of Wild Fauna and Flora), and are therefore protected.

Some other interesting things about owls:

The smallest owl in southern Africa is the African scops owl with a full-length in the region of 16 cm and an average weight of
65g. The largest owl in southern Africa is the Verreaux’s eagle-owl (giant eagle-owl / milky owl) with an average full-length (from
tip of beak to end of tail) of 65 cm and a weight of up to 2.3kg.

The smallest owl in the world is the elf owl (Micrathene whitneyi), weighing as little as 31 g and having a full-length of only 13.5 cm. The largest owl in the world, by length, is the great grey owl (Strix nebulosa), which measures about 70 cm on average. It is not the heaviest however, the heaviest (and largest winged) owls in the world are two similarly sized eagle owls – the Eurasian eagle-owl (Bubo bubo) and Blakiston’s fish owl (Bubo blakistoni). These two species can both attain a wingspan of 2 m and a weight of 4.5 kg in the largest females. The Verreaux’s eagle-owl (South Africa’s largest owl) has been known to take prey species up to the size of monkeys and even small antelope.

The pearl-spotted owlet often hunts and feeds upon small birds. As a result, small birds (when they discover one of these owls in the area) tend to gather together and harass the owl until it leaves (known as mobbing). Often the small birds will fly and attack the owlet when it is facing away from them. In order to protect itself from the mobbing birds, and avoid being pecked from behind, the Pearl-spotted owlet has adapted to have “false-eyes” on the back of its head to confuse the birds into thinking that it is still watching them even though its head is facing away.

Not all owls hoot, and owls can make a wide range of other sounds, such as screeches, whistles, barks, growls, rattles and hisses. Barn owls, in particular have a very eerie, blood-curdling, screeching call that sounds like a human being tortured.

A group of owls is called a parliament and a baby owl is known as an owlet.

In ancient Greece, the Little Owl was the companion of Athena, the Greek goddess of wisdom, which is one reason why owls symbolize learning and knowledge. But Athena was also a warrior goddess and the owl was considered the protector of armies going into war. If Greek soldiers saw an owl fly by during battle, they took it as a sign of coming victory.

Images: Verreaux’s eagle-owl (main image), Marsh Owl, Southern white-faced scops-owl, Barn owl (Photo by Sean Bissett), Southern white-faced scops-owl, Spotted eagle-owl (Photo by Jonathan McCormick), Verreaux’s eagle owl, African scops-owl, Pearl-spotted Owl (facing forwards), Pearl-spotted Owl (facing away).