An Experimental Design for Investigating Winter Bird Depredation at South Texas Feedlots

INTRODUCTION Large aggregations of birds concentrating around livestock feedyards during fall and winter months have been a common occurrence in many parts of the country (Besser et Extensive utilization of livestock feedyards by these flocking birds has been reported to result in economic losses to the feedyard operator due to feed consumption. In Colorado, seasonal feed losses to starlings obtaining 50% of their daily food at feedlots were calculated to be $84 per 1,000 birds; seasonal losses to red-winged blackbirds (Ageliaus phoeniceus) obtaining 10% of their daily food at feedlots were calculated to be $2 per 1,000 birds (Besser et al. 1968). In Texas, Coon (1974) estimated seasonal feed losses to cowbirds (Molothrus ater) obtaining 30% of their daily food at feedlots to average $35 per 1,000 birds. In California, Palmer (1976) suggested winter losses due to blackbird depredation at an average 10,000-head cattle feedlot to be nearly $5,000 per year. In an earlier California study, Levingston (1967) reported that one million starlings (Sturnus vulgaris) in a California feedlot resulted in losses of $1,000 per day.