The effects of ingested plastic on seabirds: correlations between plastic load and body condition.

Multivariate analyses were used to assess the independent influences of body size, ingested plastic load and parasite load on bird mass and on an index of fat reserves in great shearwaters and blue petrels. PLastic load was negatively correlated with body condition in the sample of blue petrels collected after the post-nuptial moult, but differences in reproductive status may account for this negative correlation. Ingested plastic loads had no apparent effect on blue petrels and great shearwaters collected at the same stage of reproduction, despite high plastic loads in some individuals. The limitations of using correlations to demonstrate the effects of plastic ingestion are discussed.