letting nature back in

The African wood owls are particularly vocal in our neighbourhood. But apart from sometimes seeing a dark silhouette at dusk or a flash of flying feathers illuminated by a street light at night, we seldom catch even a glimpse of them.

African wood owls (Strix woodfordii) are very chatty, especially at dusk and into the night, and so we are often aware of their presence despite them mostly not being visible. Their call is the stereotypical “whoo” and also they duet in pairs with an almost dovelike cadence.  There are several recordings of their calls here: https://www.xeno-canto.org/species/Strix-woodfordii

Recently one evening after two birds flew into a nearby tree, thinking they may well be owls I reflexively called “whoo” in the best owl enunciation I could muster. Much to my amazement, quick as a flash came back a response, a loud “whoo”. After a brief call and response between me and owl, the owls took over in their more complicated and nuanced duet, which Roberts represents as “Who-who, Who-who-who are-you” with the female calling at a slightly higher pitch than the male, and outclassed I lapsed into silence – much to the relief of our two dogs.

Because of the nocturnal habits of the African wood owls the only photos I have of wood owls were taken at the African Raptor Centre in KwaZulu-Natal, South Africa. This picture of the free-flying display bird perched on the glove of the handler shows the petite stature of the African wood owl

Wood owls are relatively small, weighing in at about 250 g (males) and 335 g (females), and being 30-36 cm in length. To most human eyes they are undeniably cute. As their name implies, their natural habitat is forest and woodland and in some regions, such as ours, they have adapted to exotic plantations and well-treed gardens.

I was intrigued that the scientific name for the African wood owl – Strix woodfordii – also includes “wood” in the name. The reason is that it is named for Colonel E.J.A. Woodford (1761–1835), a British soldier of the Napoleonic Wars who was also a naturalist, and so the “wood” in its scientific name is coincidental. Interestingly, in isiZulu the male and female African wood owls are named differently  –  uMabhengwane (female) and  uNobathekeli (male).

The African wood owl at the African Raptor Centre during its free-flying display

Adult African wood owls live in territorial pairs. They hunt usually from low perches but they may also hawk insects or bats in flight, or glean insects off foliage. They prey mostly on insects and small birds and nestlings, and they also eat centipedes, rodents and other small mammals, frogs and small reptiles sometimes including snakes.  

Three rescued African wood owls who are permanent residents at the African Raptor Centre. As far as I remember the bird on the left is blind

The other species of owl that we hear calling in our garden, although not as often as the wood owl, is the spotted eagle-owl (Bubo africanus). On some nights though we have heard both the duet of the wood owls and the duet of the eagle-owls, and one night most surprisingly we glimpsed all four owls flitting into the same tree.

The male spotted eagle-owl often initiates the duet with a two-note call to which the female responds with a deeper three-note call. Recordings can be heard here https://www.xeno-canto.org/species/Bubo-africanus. Some of the recordings are better than others at capturing the duet.

At an average weight of 700 g and being 43-47 cm in length, the spotted eagle-owl is quite a bit heavier and longer than the wood owl. Unlike the wood owl the spotted eagle-owl has noticeable ear tufts. 

A spotted eagle-owl, looking almost feline, during its flight display at the African Raptor Centre

Whereas the African wood owl is dependent on well-wooded habitats, the spotted eagle-owl can survive in a variety of habitats, from desert to scrubland, grassland and forest margins, and some have adapted to urban environments too.

The spotted eagle-owl showing something of its power

Spotted eagle-owls mostly hunt at night, commonly swooping down on roosting animals. Prey includes small mammals such as hares and bushbabies, birds, bats, insects, spiders, snails, crabs and millipedes. They are also known to take poisonous snakes and will also feed on carrion.

A spotted eagle-owl in its enclosure at the African Raptor Centre

Breeding pairs of spotted eagle-owls often nest on the ground. According to Roberts, in a study of 269 nests, 61% were on the ground, 26% in trees, and 11% on buildings. The nest is basically a scrape on the ground but is usually concealed in some way such as by vegetation, rocks or debris or because it is on a ledge or in a hollow or gulley. Unsurprisingly for mostly ground-nesting birds, the owls can defend their young aggressively, even threatening and attacking an intruder with wings out and bill snapping. As another strategy, they may perform distraction displays such as flopping about on the ground while emitting mewing calls (Roberts).

I took this picture, from an upstairs window of an adjacent house, of a spotted eagle-owl at dusk on a roof in a seaside town, Onrus, in the Western Cape

Threats to the spotted eagle-owl include interference from humans, for example with young birds still too young to fly being removed from the vicinity of nests with people mistakenly believing they are in trouble. Spotted eagle-owls have a high casualty rate from vehicle collisions and also they get entangled in barbed wire fences. Drowning is another hazard recorded by Roberts.

All raptors, including owls, are affected by rat poisons that they commonly ingest from eating poisoned prey. The effect is usually fatal, but lower doses can result in significant health issues that ultimately lead to death. For my earlier post on raptors and rat poison see here.

By way of comparison, this is the larger Cape eagle-owl, which I photographed early one morning in the Central Kalahari Game Reserve in Botswana

The Cape eagle-owl with the male’s weight averaging 1.0 kg, and the female 1.2 kg, and being about 50 cm in length, is larger than the spotted eagle-owl. It is less common than the spotted eagle-owl. The majority of its prey comprises small mammals, including hyraxes, cane rats and hares, although it will also hunt other species, including bats and many species of birds.

For information about a specialised Owl Rescue Centre in North West Province in South Africa see http://www.owlrescuecentre.org.za/Home/.  Projects run by the centre include not only the rescue and rehabilitation of owls and providing sanctuary for those that cannot be released, but also a rat trapping service and an ongoing plastic recycling project turning plastic waste into owl houses, bat houses and bee hives. (See also on Facebook at https://www.facebook.com/OwlRescueCentre/).

Sources:

Molepo, Dikobe & The Rural Citizen Science Birding Project, Team Finches (Tshegofatso Motene, Dipolelo Mahlo, Lizzy Masinga, Percy Mafumane and Tsietsi Moraba). [n.d.] African wood owl. South African Biodiversity Institute (SANBI). https://www.sanbi.org/animal-of-the-week/african-wood-owl/; Roberts VII Multimedia PC Edition.  1997-2016 Southern African Birding. For details go to http://www.sabirding.co.za/roberts7/portal.html

Posted by Carol