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

Area of Science:

• Environmental Toxicology
• Wildlife Ecology
• Ecotoxicology

Background:

• Preremediation studies at Crab Orchard National Wildlife Refuge (CONWR) identified polychlorinated biphenyls (PCBs) in starling chicks (Sturnus vulgaris).
• Observed effects included decreased nest attentiveness, reduced fledging success, and increased chick mortality.
• Dietary exposure was suspected but not previously documented at CONWR.

Purpose of the Study:

• To develop a predictive equation for starling chick carcass PCB concentrations.
• To correlate PCB levels in ingested animal matter with PCB levels in chick carcasses.

Main Methods:

• Collected stomach contents from 140 starling chicks from contaminated and reference sites in 1995-1996.
• Separated stomach contents into animal, plant, and mineral matter.
• Analyzed composite animal matter samples for PCBs (Aroclor 1254) and correlated with carcass concentrations.

Main Results:

• Animal matter constituted the majority (76%) of stomach contents, with no significant difference in proportion across locations.
• Mean PCB concentrations in animal matter were significantly higher in chicks from contaminated sites (1.82 ± 1.17 mg/kg) compared to reference sites (<0.24 mg/kg).
• A strong correlation (r=0.91, p<0.005) was found between PCB concentrations in stomach contents and chick carcasses.

Conclusions:

• Ingested animal matter is a significant source of PCB exposure for starling chicks at CONWR.
• The developed regression equation (Y = 6.19 * X^1.398) explains 82% of the variability in starling carcass PCB concentrations.
• This study provides a method to estimate dietary PCB exposure in starling chicks.