Avian use of rice-baited corn stubble in east-central South Dakota

Blackbirds (Icteridae) cause substantial damage to ripening sunflower (Helianthus annus) in the northern Great Plains. One management option to reduce damage is to bait spring-migrating blackbirds with the compound DRC-1339 (3-chloro-p-toluidine hydrochloride). In March and April 1994 and 95, we evaluated nontarget risks associated with use of DRC-1339-treated rice baits broadcast in fields of corn stubble in east-central South Dakota. In 1994, we counted 159 nontarget birds during 105 15-min observations in rice-baited and unbaited plots. In 1995, 178 nontarget birds were recorded during 816 1-min periods. We detected no difference in granivorous bird abundance between rice-baited and unbaited plots in either year (Pʹs 0.05). Of the 15 identified nontarget species, meadowlarks (Sturnella spp.) and ring-necked pheasants (Phasianus colchicus) probably are most at risk because of their high susceptibility to DRC-1339. Prebaiting blackbirds into small plots placed away from field edges and diluting bait with untreated rice might mitigate nontarget losses.