Rediscovery of the Congo Bay Owl: 2

Prigogine (14) suggested that the Oriental Bay Owl and Congo Bay Owl are less closely related than was once thought. The Oriental Bay Owl is lighter in colour and has a less compressed bill, with larger feet and talons. It nests in large hollows in trees, where adults also rest during the day (1, 2, 8,11). Unlike the Congo Bay Owl, it is apparently not known to occur above 1,500 m, to rest on the ground in grassland, or to be associated with grassland/forest mosaic vegetation types.

While working at Itombwe, one of us (TMB) searched most nights for nocturnal birds and mammals for 1-2 hours before dawn and 1-3 hours after dusk. Although several species of owl, nightjar and galago were heard and recorded, no calls were heard which might be attributed to the Congo Bay Owl.

Conservation importance of Itombwe
The part of Itombwe which is of conservation importance ranges in elevation from 600 to 3,470 m, covers roughly 16,000 km2, and holds the largest tracts of transition forest, montane forest and bamboo in central Africa (15). A total of 563 bird species are recorded for Itombwe (3,13,15,16,17). Of these, about 60% are 'forest dependent' (13,17). This makes Itombwe the richest single forest for birds in Africa (20). In addition, Itombwe holds about half (83) the total number of montane bird species in the whole of Africa, at least 94% (98 of 104) of the bird species characteristic of the transition and montane forests of the Albertine (Western) Rift, and no less than 89% (34 of 38) of montane and transition-forest bird species endemic to the Albertine Rift (17). The birds in this last category include three species listed in the Red Data Book as being of 'Indeterminate' status: Congo Bay Owl, Schouteden's Swift, Schoutedenapus schoutedeni, Prigogine's Nightjar, Caprimulgus prigoginei; there are also five 'Rare' species and nine species listed as either 'Of special concern' or 'Near-threatened' (4,10). It is not surprising, therefore, that Itombwe is presently ranked as the single most important forest for bird conservation in continental Africa (5). What is surprising, however, is that no part of Itombwe enjoys legal conservation status.

While large areas of all major vegetation types remain more or less intact in Itombwe, this forest is under increasing threat from pastoralists, farmers, pit-sawyers, miners and hunters. The human population in the region continues to grow rapidly and thousands of refugees from Burundi and Rwanda live in camps at the base of Itombwe's eastern escarpment and to the north. Of particular concern is the rapidly advancing agricultural front we observed all along the southern and western edges of the gallery montane forest system, in which we found the Congo Bay Owl. This is the favoured habitat for conversion to pasture and to maize fields. The rate of conversion has obviously accelerated enormously in the last two years as famine, related to failing corn crops, forces people to open up much larger areas than was formerly the case.

Conservation action
Conservation action is needed in order to minimise, and eventually halt, the damage to the Itombwe Massif and its wildlife. Possible approaches to such action have been outlined by Prigogine (17) and Wilson and Catsis (20), and further discussions on this issue are now occurring in light of the current situation. Whatever approaches are chosen to help maintain the high conservation values of Itombwe, they must take into careful consideration the serious current political, economic, and security problems of the region, the needs of the dense human population which borders the Itombwe Massif, as well as those of the sparse human population within.

Regarding the particular needs of the Congo Bay Owl, the present paucity of information on its distribution, numbers, ecology and behaviour remains one of the more serious obstacles to its conservation. The search for, and study of, this species in Itombwe and in other montane forests of the Albertine Rift must continue.

Acknowledgements
This work was funded by The Wildlife Conservation Society. TMB's participation was supported by Berggorilla & Regenwald Direkthilfe and Zoo Atlanta. We thank Mr Omari Ilambu for leading the Itombwe survey, Dr. Michel Louette for examining the type specimen at Tervuren, and the Institut Zairois pour la Conservation de la Nature for logistical support and for authorisation to work in Itombwe.

References

1. Ali, S. and Ripley, S.D. 1987. Compact Handbook of the Birds of India and Pakistan. Second edition. Delhi: Oxford University Press.
2. Burton, J.A. (ed) 1973. Owls of the world: Their evolution, structure and ecology. London: Peter Lowe.
3. Butynski, T.M., Agenonga, U., Ndera, B. and Hart, J. 1996. Ornithological survey of south-eastern Itombwe, eastern Zaire: A preliminary report. Unpublished report.
4. Collar, N.J. and Stuart, S.N. 1985. Threatened birds of Africa and related islands: The ICBP/IUCN Red Data Book, Part 1. Cambridge: International Council for Bird Preservation.
5. Collar, N.J. and Stuart, S.N. 1988. Key forests for threatened birds in Africa. ICBP Monograph No. 3. Cambridge: International Council for Bird Preservation.
6. Dinesen, L. Lehmberg, T., Svendsen, J.O., Hansen, L.A. and Fjeldså, J. 1994. A new genus and species of perdicine bird (Phasianidae, Perdicini) from Tanzania: A relict form with Indo-Malayan affinities. Ibis 136: 2-11.
7. Dowsett-Lemaire, F. 1990. Eco-ethology, distribution and status of Nyungwe Forest birds (Rwanda). In R.J. Dowsett (ed) Survey of the fauna and flora of Nyungwe Forest, Rwanda, p31-85. Cambridge, England: Tauraco Press.
8. Grossman, M.L. and Hamlet, J. 1965. Birds of prey of the world. London: Cassell.
9. Gysels, H. and Rabaey, M. 1962. Taxonomic relationships of Afropavo congensis Chapin 1936 by means of biochemical techniques. Bull. Soc. Roy. Zool. Anvers 26: 71-79.
10. Louette, M. 1990. A new species of nightjar from Zaire. Ibis 132: 349-353.
11. Mackinnon, J. and Phillipps, K. 1993. A field guide to the birds of Borneo, Sumatra, Java, and Bali. Oxford: Oxford University Press.
12. Moreau, R.E. 1966. The bird faunas of Africa and its islands. London: Academic Press.
13. Prigogine, A. 1971. Les oiseaux de l'Itombwe et de son hinterland. Vol. 1. Annales du Musee Royal de l'Afrique Centrale, Tervuren. Serie 8, Sciences Zoologiques, No. 185.
14. Prigogine, A. 1973. Le statut de Phodilus prigoginei Schouteden. Gerfaut 63: 177-185.
15. Prigogine, A. 1978. Les oiseaux de l'Itombwe et de son hinterland. Vol. 2. Annales du Musee Royal de l'Afrique Centrale, Tervuren. Serie 8, Sciences Zoologiques, No. 228.
16. Prigogine, A. 1984. Les oiseaux de l'Itombwe et de son hinterland. Vol. 3. Annale du Musee Royal de l'Afrique Centrale, Tervuren. Serie 8, Sciences Zoologiques, No. 243.
17. Prigogine, A. 1985. Conservation of the avifauna of the forests of the Albertine Rift. In Diamond, A.W. and Lovejoy, T.E. (eds) Conservation of tropical forest birds, 277-295. ICBP Technical Publications No. 4. Cambridge: International Council for Bird Preservation.
18. Schouteden, H. 1952. Un strigide nouveau d'Afrique noire: Phodilus prigoginei nov. sp. Rev. Zool. Bot. Afr. 46:423-428.
19. Urban, E.K., Fry, C.H. and Keith, S. (eds) 1986. The birds of Africa. Vol II. London: Academic Press.
20. Wilson, J.R. and Catsis, M.C. 1990. A preliminary survey of the forests of the 'Itombwe' mountains and the Kahuzi-Biega National Park Extension, East Zaire, July-September 1989. Unpublished report.

Copyright © African Bird Club 1997. All rights reserved.