Cape Eagle Owl
Bubo capensis
Status: Near Threatened

Distribution and abundance


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This large and apparently scarce nocturnal owl, has three subspecies in Africa. However, just one race (B c capensis) is confined to southern Africa and is found in a distributional arc similar to the Verreaux's Eagle through Zimbabwe, South Africa and the western parts of Namibia (Mendelsohn & Allan 1997). Its dependence on rocky uplands may explain its absence from essentially flat parts of the central subcontinent. In 1997 there were just three records for Namibia namely (i) a bird at Lorelei on the Orange River in 1956 (Clinning 1980); (ii) a breeding pair near the coast at Lüderitz in 1983 (Walter et al. 1986); (iii) an injured bird found on the farm Namibgrens, on the escarpment 140 km sw of Windhoek in 1987 (Brown 1987, Boyer & Bridgeford 1988). Several specialists predicted it would be more widespread than found (Steyn 1982, Walter et al. 1986) and may even occur as far n as s Angola (Kemp & Calburn 1987). Since then numerous records have extended its range from the Swakop River Valley and Brandberg (Mallet-Veale 1996), to the Ugab River in the Namib Desert (Swanepoel 2003) and as far north as 9 km from the Cunene River in the Kaokoveld (W Swanepoel pers obs). Intimate knowledge of habitat preferences were used by Swanepoel to successfully locate owls at the Zebra River in the Tsaris Mountains, on the Brandberg massif, at the Khowarib Schlucht, (Swanepoel 2003) and in the Okakora Mountains near the Cunene River at 17o 13' S (W Swanepoel pers obs). It is probably safe to assume, therefore, that where montane areas are incised by river valleys in arid areas and hyrax or rock rabbits are available, Cape Eagle Owls are likely to occur in Namibia.

Ecology

Elsewhere in southern Africa the Cape Eagle Owl prefers relatively mesic rocky habitat so it is unusual that it is found in very arid areas of the Namib Desert. However, most of these are associated with river valleys and the owl shows a preference for rocky or mountainous terrain with cliffs, gorges, canyons and boulder strewn hillsides, especially those consisting of igneous (e.g. granite) or sedimentary rock (e.g. dolomite, limestone: Swanepoel 2003). It appears to have habitat preferences very similar to Verreaux's Eagle and Rock Pigeon and where these and rock hyrax or rabbit are found the bird is likely to occur (W Swanepoel pers obs). The bird hunts mainly (80%) mammals - small and large - in other parts of s Africa (Allan 1995) but its diet in Namibia is poorly known other than records of Red Rock Rabbit, an unidentified rat, Striped Mouse and a Hartlaub's Gull from Lüderitz (Walter et al.1986). The one breeding record is from July-August at the coast, towards to the end of the usual breeding period for this species (May-September: Kemp 2005).

Threats

Few are known for this species because its life-history in Namibia is so poorly known. However its habitat preferences and range suggest that overgrazing by goats in rocky hillsides may be the only threat to its ecology. Low density of people in these areas and the advent of conservancies in many regions suggest this will be a minor threat.

Conservation status

Prior to the work of Swanepoel this species would have been categorized as Rare and Peripheral. However, it is clear that substantial populations occur in Namibia and as an endemic subspecies it requires protection and research. It is therefore given Near-Threatened status because its population is likely to be small.

Actions

There are numerous other localities in Namibia with suitable habitat for the Cape Eagle Owl and where its preferred prey probably occur (Swanepoel 2003). Further research will determine if these predictions are correct and together with density estimates of owls, will allow a first estimate of the population size in Namibia. Research on prey specificity and population fluctuations will greatly help in understanding its population ecology in Namibia.

From: Simmons RE & Brown CJ 2006. Birds to watch in Namibia: red, rare and endemic species. National Biodiversity Programme, Windhoek, Namibia

References

Allan DG 1995 The diet of the Cape Eagle Owl. J African Rapt Biology 10: 12-27.

Boyer HJ, Bridgeford PA 1988 Birds of the Naukluft Mountains: an annotated checklist. Madoqua 15: 295-314.

Brown CJ 1987. Another Cape Eagle Owl record from Namibia. Gabar 2: 26-27.

Clinning CF 1980. The occurrence of the Cape Eagle Owl in South West Africa. Madoqua II: 351-352.

Mendelsohn JM, Allan DG 1997 Cape Eagle Owl. In: Harrison JA, Allan DG, Underhill LG, Herremans M, Tree AJ, Parker V, Brown CJ (eds). The Atlas of Southern African Birds. Vol. 1: 590-591 . BirdLife South Africa, Johannesburg.

Kemp AC, Calburn S 1987. The Owls of Southern Africa. Struik Winchester, Cape Town.

Kemp AC 2005 Cape Eagle Owl. In: Hockey PAR, Dean WRJ, Ryan PG, (eds.) Roberts Birds of Southern Africa, 7th ed. Black Eagle Publishing, Cape Town.

Mallet-Veale S 1996. Owls - Strigiformes - Eulen. Lanioturdus 29: 50-54.

Steyn P 1982. Birds of Prey of Southern Africa. David Philip, Cape Town.

Swanepoel W 2003. New records and notes on the distribution of the Cape Eagle Owl in Namibia. Bird Numbers 12: 21-24.

Swanepoel, Wessel personal observation (wswanepoel@transnamib.com.na).

Walter A, Walter JP, Brown CJ 1986. Breeding record for the Cape Eagle Owl in SWA./Namibia. Madoqua 14: 429-431.

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