Organochlorine pesticide residues in uropygial glands and adipose tissue of wild birds

Abstract

The literature contains a large body of knowledge on the avian uropygial (preen or oil) gland. Much of this information~ particularly as regards its anatomy and physiology~ is superbly reviewed by LUCAS and STETTENHEIM (1972). This subcutaneous gland~ especially large in aquatic birds~ is typically bilobed and terminates in a nipple-like projection at the base of the bird's tail. Its holocrine~ oily secretions function chiefly to waterproof and condition the bird's plumage. The secretions have been analyzed chemically by a number of investigators including APANDI and EDWARDS (1964)~ HAAHTI and FALES (1967)~ SAITO and GAMO (1968)~ and EDKINS and HANSEN (1972); their reports generally revealed the lipophilic nature of the gland and disclosed the presence of aliphatic waxes~ triglycerides~ phospholipids~ and other components in the gland. The lipoidal nature of this gland should make it a possible repository and excretory organ for chlorinated hydrocarbon pesticides and pollutants. DINDAL (1970) found high concentrations of DDT and its metabolites in uropygial glands of two species of ducks. After surgically removing glands from three species of caged birds~ GREICHUS and GREICHUS (1974) reported that d�8 can be found in secretions emanating from lipoid bodies in the skin. More recently CHARNETSKI and STEVENS (1974) concluded that wild ducklings of several species (p 675) ". . , can excrete lipid soluble insecticides and their metabolites through the preen gland." The present investigations extend these earlier studies by examining pesticide contents of uropygial glands as compared with those of adipose tissue depots taken from a large variety of wild birds of diverse habits and habitats. Materials and Methods Bird specimens used in the present study were obtained chiefly in Florida from 1969 to 1974. Ai1 were wild birds taken in a variety of ways -- shotgun~ found freshly killed at TV towers~ on roadsides and on beaches. The 53 birds embraced I0 orders�87 15 families~ 23 genera~ and 28 species. They included aquatic~ semiaquatic and terrestrial species~ piscivores~ carnivores~ insectivores, scavengers�87 long- and short-distance migrants~ and non-migrants. From each individual a small amount (ca i g) of adipose tissue was removed from the subcutaneous interfurcular depot. The uropygial gland was carefully dissected out intact and any feather tuft at its opening was trimmed off prior to weighing and