Predicting starling chick carcass PCB concentrations from PCB concentrations in ingested animal matter

Preremediation studies at Crab Orchard National Wildlife Refuge (CONWR) rev ealed statistically significant accumulations of polychlorinated biphenyls (PCBs) and effects in starling chicks (Sturnus vulgaris) from contaminated sites, including decreased nest attentiveness, decreased hedging success, a nd an increase in chick mortality. Although the expected route of exposure for starling chicks is thought to be via diet, this has not: previously bee n documented at CONWR. The purpose of this study was to develop an equation to predict starling chick carcass PCB concentrations from PCB concentratio ns in ingested animal matter During 1995 and 1996, stomach contents from 14 and 22 starling chicks collected from contaminated and reference sites, re spectively, were evaluated. Animal, plant, and mineral matter in the stomac h contents were separated and animal matter from stomachs of individuals fr om the same nest were combined, dried, and percent dry weight calculated. C omposite samples of animal matter were then analyzed for the presence of PC Bs (Aroclor 1254). Stomach contents were primarily composed of animal matte r (76%), and the percent animal matter in the stomachs did not differ signi ficantly among locations (range = 38.4% to 100%). The mean PCB concentratio n in composite samples of animal matter from stomachs of chicks collected f rom contaminated sites (1.82 +/- 1.17 mg/kg) was significantly greater than the concentrations in composite samples from two reference locations (<0.2 4 mg/kg). PCB concentrations in stomach contents were correlated (Pearson c orrelation coefficient = 0.91, p < 0.005) with concentrations in carcasses of chicks from which the stomachs had been collected. The regression TC = 6 .19 x X-1,X-398, where Y = starling chick carcass PCB concentration and X = starling stomach animal matter PCB concentration, indicated that PCB conce ntrations in consumed animal matter accounted for 82% of the variability in starling carcass concentrations.