POTENTIAL RISK TO RING-NECKED PHEASANTS FROM APPLICATION OF TOXIC BAIT FOR BLACKBIRD CONTROL IN SOUTH-DAKOTA

Blackbird (Icterinae) damage to sunflowers in the northern Great Plain s can be locally severe. One approach to alleviating depredation press ure is to reduce blackbird populations through application of brown ri ce bait treated with the avicide DRC-1339. Because such baiting Mn pot entially affect nontarget species, we conducted pen and field trials t o evaluate the potential risk from avicide baiting to ring-necked phea sants (Phasianus colchicus). Although most female pheasants in pen tes ts preferred cracked corn and sorghum, 2 of 12 birds preferred brown r ice. In 4-day trials within a 0.2-ha Right pen, pheasant consumption o f brown rice from bait swaths simulating field bait applications was n ot affected by the presence of an alternate bait swath of cracked corn . Pen trials to evaluate possible avoidance responses following a subl ethal dose of DRC-1339 showed that 2 of 7 birds shifted from their pre viously preferred feeding sites following exposure to the avicide. Dur ing March and April 1995, we recorded pheasant numbers in 6 pairs of 0 .8-ha plots in corn stubble fields that were either baited with brown rice or were designated as reference plots. Overall, use of test plots was low, but at the most heavily used sites, pheasants visited refere nce plots more than baited plots (P = 0.004). We conclude that (1) phe asants will eat brown rice treated with DRC-1339; and (2) although cha nces of exposure to an acute lethal dose can be reduced by increasing the dilution. harmful repeated doses could be obtained because avoidan ce of feeding sites, following sublethal exposure, cannot be assumed.