Two-choice preference testing of taste repellency in Quelea quelea

A three method laboratory preference testing program has been developed for evaluating candidate taste repellents on quelea (Quelea quelea). In all three methods, the birds are first adapted to the test conditions and food types and then offered a choice between the control food and one test food; preference is measured as proportion of total food consumed. A four-day individual cage test has been satisfactory for evaluating quelea response to 15 bird-resistant sorghum varieties. To avoid preference biases due to visible differences in shape, size, and color between the control and test foods, the foods were pelleted, and the birds were adapted to feed in near-darkness during the tests. A similar test, using surface-coated millet has been used to evaluate the repellency of constituents extracted from bird-resistant sorghums. In these cage tests, the repellents are ranked primarily by t test results. In the third method, a six-day enclosure test designed to simulate field conditions, five birds in a 2.5 by 2.4 by 2.2-m screened enclosure were offered a choice between tannin-coated and control sorghum heads. Preference was measured by analysis of variance. In general, experience indicates that, if precautions are taken to reduce stress and minimize extraneous factors, such as visual cues, adequate separations can be made among the test repellents with quite simple testing regimes.