O. Gy. Dely szerk.: Vertebrata Hungarica 20. (Budapest, 1981)

Demeter, A.: Small mammals and the food of owls (Tyto and Bubo) in Northern Nigeria 127-136. o.

Reproduction seems to be quite asynchronous in the various species. In the first half of the rainy season Myomys daltoni and Mastomys cf. erythroleucus showed little intensity of breeding, whilst other species, especially bats, were reproductively active. These observations are in accordance with the findings of HAPPOLD (1974). Ten species of bats are now recorded for Yankari G.R.. In addition to the ones listed above, M. GARTSHORE (pers. comm.) collected Hipposideros caffer at Wikki, Scotophilous leucogaster and Scotoecus albofuscus at Dimil warm spring. The food of the Barn Owls is similar to that recorded by other workers (DEAN, 1973, 1974; HEIM DE BALSAC, 1965; LAURIE, 1971; NIETHAMMER 1975; VERNON, 1972), although it can clearly be seen that prey availability greatly influences the diet. The single Barn Owl finding smaller number of its generally dominant prey, Mastomys spp. in the reserve, preyed readily on other available rodents and invertebrates. This generalist behaviour by Barn Owls in southern Africa has been also been observed by VERNON (1972). Spotted Eagle-Owls have also adapted to catching highly variable prey. According to MACWORTH-PRAED & GRANT (1970: 496) it is a "very inoffensive bird for its size", and its food consists of "very largely insects, especially beetles, with occassionally birds, small mammals and reptiles". However, my findings agree with NEL (1969), NIETHAMMER (1975) and SIEGFRIED (1965) who found that Spotted Eagle-Owls preyed mainly on small mammals. Nevertheless, reports on stomach contents consisting solely of insects (BENSON, 1962; CARNEGIE, 1961 ), as well as my observations at Kaiban Hills suggest that in the absence of mammals, this predator readily switches to other potential prey. It is interesting to note that Acomys cahirinus was also taken, which LAURIE (1971) found to be immune to prédation by Barn Owls in Serengeti National Park, Tanzania

. All bats taken by the owls were microchiropteran

. HEIM DE BALSAC (1965) found remains of the two fruit bat species recorded at Wikki in pellets of T. alba at Bamako, Mali Republic. ACKNOWLEDGEMENTS I thank Alhaji JIBRIN JIA, former Principal Game Preservation Officer, for granting permission to work in Yankari G. R. and for providing facilities in the reserve. I am indebted to Mr. and Mrs. P. J. MARSHALL for their help during my stay in the reserve, and to Mr. AHMADU MAKAMA for his able assistance in the field. I am most grateful to Dr. R. HUTTERER for identifying the shrews, and to Drs. G. TOPÁL, H. STEINMANN and Mr. L. ÁDÁM for identifying the bat and insect remains. I thank Dr. D.C.D. HAPPOLD for commenting on an earlier version of the manuscript. REFERENCES ANADU, P. A. (1979): A study of bait selection in small African rodents. - Acta Theriologica, 24 (36): 501-511. BENSON, C. W. (1962): The food of the Spotted Eagle-Owl Bubo africanus. - Ostrich, 33 (4): 35. CARNEGIE, A.J.M. (1961): The stomach contents of a Spotted Eagle-Owl (Bubo africanus). Ostrich, 32 (2): 97. CHEESEMAN, C.L. & DELANY, M.J. (1979): The population dynamics of small rodents in a tropical African grassland. - J. Zool. (Lond.), 188: 451-475. DEAN, W.H.J. (1973): Analysis of a collection of Barn Owl Tyto alba pellets from Warmbaths, Transvaal. - Zool. afr., 8 (1): 75-81. DEAN, W.R.J. (1974): Analysis of Tyto alba pellets from Angola. - Zool. afr., 9 (1): 89-91. DEMETER, A. (1978): Food of a Barn Owl Tyto alba in Nigeria. - Bull. Nigerian Orn. Soc. 14: 9-13. DOBROZHOTOV, B., MEYLAN, A.& ARATA, A. (1978): Studies on ecology and systematics in the genus Mastomys in Nigeria and its association with Lassa fever, p. 63 in: Abstracts of Papers, II. Congressus Theriologicus Internationalis, Brno, Czechoslovakia, (ed. Obrtel, R., Folk, C. & Pellantová, J.) pp. 461. GEERLING, C. (1973): The vegetation of Yankari Game Reserve: its utilization and condition. Bulletin 3, Department of Forestry, University of Ibadan, Ibadan, pp. 49. GEERLING, C. (1978): Birds of Yankari Game Reserve, Nigeria. - Bull. Nigerian Orn. Soc, 14: 82-83.