Diets of the Red-billed Quelea (quelea Quelea) in the Awash River Basin of Ethiopia

INTRODUCTION An understanding of the feeding ecology of the red-billed quelea (Quelea quelea) is necessary for a comprehensive assessment of the potential impact of this species on cereals development. Queleas are reported to subsist primarily on wild Gramineae (Ward 1965a; Gaston 1976), but their mobility and tendency to feed in large aggrega-tions readily adapts them to becoming a major cereal crop pest (Dyer & Ward 1977). Currently, conflicting evidence exists as to the factors involved in attacks on cereals and the relationship of depredation to the availability of wild foods. In Nigeria, Ward's (1965a) findings indicated queleas prefer small wild grass seeds, with cultivated sorghum being extensively damaged only when the supply of grass seeds was depleted. (in press) have found queleas dispersing from grassland regions into areas of cereals cultivation where appreciable damage occurs to ripening sorghum at a time when wild grass seeds should be abundantly available. At present the factors affecting depredation of cereals are poorly understood. This paper examines the overall diets of Quelea quelea aethiopica (Sundevall) by sex and age in relation to depredation of the five cereals cultivated in the Awash River Basin and in terms of the types and sizes of food items eaten. Samples were collected over a one-year period from two ecologically diverse agricultural zones of the Basin, and findings are compared with those of Ward (1965a) from a considerably different ecological setting in the Lake Chad zone of Nigeria. 2 , is conventionally divided into four ecological zones; tropical highlands, 1800 m and above; hot subtropical, 1100-1800 m; semi-arid, 600-1100 m; and arid, below 600 m (F.A.O. survey 1965). Sampling sites were established in both the hot subtropical and semi-arid zones. The hot subtropical zone sites were located in the upper Awash River region (Fig. 1). The area is intensively cultivated with rainfed cereals: maize (Zea mays), tef (Eragrostis tef), sorghum (Sorghum biocolor), wheat (Triticum durum), and barley (Hordeum vulgare). Natural vegetation includes scattered Acacia spp. and prevalent Gramineae of Paniceae and Andropogoneae. The long-term rainfall average is 820 mm per year, with the main rains falling from late June into September; an erratic short rains period occurs from March to May in most years. The elevation of the area ranges from 1500-1700 m. The semi-arid zone sampling sites were located in the middle Awash River region. The area is characterized by extensive tracts of dry bush and short-grass savanna …