Evaluation of chemical repellents for reducing crop damage by Dickcissels in Venezuela

In Venezuela, lethal control of wintering Dickcissels (Spiza americana) is considered a threat to the species survival. To help farmers protect their rice and sorghum crops from depredations by Dickcissels and to minimize the killing of large numbers of these birds, alternative non-lethal crop prote ction measures are needed. To that end, the responses of captive Dickcissel s to three bird-repellent chemicals applied to rice seed were evaluated. In one-cup feeding trials, treatments of methiocarb (0.05% g g(-1), applied a s Mesurol((R)) 75% wettable powder) and anthraquinone (0.5%, applied as Fli ght Control((R))) reduced consumption of rice by 70% relative to pretreatme nt consumption. Other anthraquinone treatments (0.05, 0.1%) and methyl anth ranilate (0.05%) were ineffective. In two-cup trials, with untreated millet as the alternative food, consumption of rice treated with 0.05 and 0.1% an thraquinone was reduced by 90% relative to pretreatment levels. Overall, Di ckcissels responded to the repellents similarly to the red-winged blackbird (Agelaius phoeniceus). Because Flight Control((R)) has been used successfu lly to reduce blackbird use of rice fields in the USA, the prospect is good for successful reduction of damage to ripening rice by Dickcissels in Vene zuela, particularly if repellent use is coupled with the establishment of a lternative feeding sites.