Date of this Version
Large (120 cm diameter) helium-filled balloons (2-10 per ha of roost) tethered about 8 m above the vegetation were effective in dispersing blackbirds and starlings from roosting sites. Bird population estimates before, during, and after balloon exposure showed that the balloons frightened the birds and caused most of them to abandon the roost. Roosting bird numbers at each of 5 test roost sites (0.3 to 1.7 ha) were reduced an average of 82% (min-max 47-100%) during 3 to 4 evenings of balloon exposure. Winds >16 km/h during the study made it difficult to keep the balloons aloft and not entangled in roost vegetation. Winds of less intensity, however, were probably beneficial since they increased balloon movement. These tests demonstrated that helium-filled balloons would be a useful addition to the list of devices used to scare blackbirds and starlings from objectionable roost sites.