4. Discussion
We observed both inter- and intra-specific variation among wild birds offered varying concentrations of
anthraquinone-treated seeds. Based upon our non-linear regression model, we predicted threshold concentrations
of anthraquinone-based repellents for Canada geese, redwinged blackbirds, and ring-necked pheasants (Table 2).
We refined the concentration–response relationship previously established for Canada geese (i.e., 70.6% and 82.3%
feeding reductions at 0.05%, 0.5% anthraquinone, respectively; Kreithen and Seamans, 1997, unpublished results).