The harvest time method as a means of avoiding quelea damage to irrigated rice in Chad/Cameroun.
Abstract
Studies on bird damage to irrigated rice were carried out in 1975-7 on 2 irrigated farms at Bongor, Chad and Yagoua, Cameroun. The level of damage in relation to the date of harvest was measured in order to assess the effectiveness of the harvest timing method of avoiding damage by migratory birds. The quelea (Quelea quelea) was considered the only serious bird pest. Observations on the movements of the Lake Chad Basin quelea population and on the date of arrival of the birds in the rice fields suggested that the safe period for the vulnerable stages of the rice crop was relatively short, from about mid-May to mid-June. In one season, the Yagoua harvest fell within this period and damage was negligible at <1%. On the other occasions, when the harvest overlapped with the birds' arrival, damage varied from 13 to 26%. The reasons for these differences are discussed. It was concluded that while the harvest timing method can eliminate quelea damage in some yr, the practical difficulty of timing the crop to a precise period means that, in other yr, when the harvest is late because of unforeseen circumstances, the spraying of nearby roosts with avicides by bird control units will be necessary.