SURVEYS OF WINTERING GREAT BUSTARDS OTIS-TARDA IN WEST-CENTRAL SPAIN

The great bustard Otis tarda population in the province of Salamanca (West-Central Spain) was studied in the north-east of the province (about 120,000 ha), which consists of a wide flat area and undulating plains. Four censuses by vehicle were conducted: autumn 1988 (521 birds), winter 1988 (523 birds), winter 1989 (578 birds) and winter 1990 (541 birds). The female-male sex-ratio was 1:1.72, 1:1.19; 1:1.12 and 1:2.1, respectively. Stubble fields are preferred in autumn and lucerne fields in winter. Illegal hunting, electrical cables and the spread of irrigated lands adversely affect the great bustard in the area, although one irrigated crop, lucerne, is the basic food during winter. The number of great bustards in Spain is estimated at 11,000-12,000 individuals, probably showing a slight increase in the west of the Peninsula, although an international census with coordinated methods and timing is necessary to evaluate properly the demography of this species in the Iberian Peninsula.