Eastern Wildlife Damage Control Conferences


Date of this Version

October 1987


A method for measuring and mapping the location of blackbird (Icterinae) damage to ripening rice over time was developed and employed in 7 commercial rice fields ranging from 20.6 to 47.4 ha in Matagorda County, Texas, during the 1985 and 1986 growing seasons. Ten evenly-spaced transects were established perpendicular to the longest side of the field and each transect was sampled at pre-determined distances. Transects were subdivided into "edge" (<= 60 m from field border) and "middle" (> 60 m from the field border) strata. The measured percent damage was compared to visual estimates for 3 samplings to assess the accuracy and precision of the latter. Measuring the percent damage to individual panicles appears to be valid, but damage may be underestimated. This sampling method may be useful for assessing the efficacy of current and proposed damage control techniques. Visual estimates were too high at low (< 5%) damage levels and too low at higher (> 5%) levels compared to measured damage.