Pollen contamination of birds

of 1957 and 1959 an unidentified substance was found adhering to the bills of four migrant species trapped at Portland Bird Observatory, Dorset. This has now proved to be an accumulation of Citrus pollen, and the following birds have been recorded carrying it:28.4.57 30-4-57 1-5-57 1-5-57 4-5-57 5-5-57 5-5-57 28.4.59 1-5-59 2-5-59 16-5-59 Adult (J Full-grown Full-grown ¥ Full-grown 0 Full-grown...