Date of this Version
In spring 1986 and 1987 I examined the relationship between blackbird abundance and sequence of rice planting near a very large roost in southwestern Louisiana to identify factors that contributed to bird damage in newly planted rice fields. Millers Lake, an eutrophic man-made lake of approximately 2,500 ha, attracts a winter roosting population that peaks at 10 to 25 million blackbirds annually. By March and April the roost declines to several thousand birds. Female red-winged blackbirds (Agelaius phoeniceus) were responsible for most rice seed losses, predominating both the roost and feeding flocks in rice fields in spring. Number of flocking birds in fields decreased with roost size, date of year, and distance from the roost. Surveys corroborated recommended planting practices: planting after 24 March coincides with decreased numbers of blackbirds in rice fields, thus reducing the potential for damage to seeded rice by foraging blackbirds.