Avian species differences in the intestinal absorption of xenobiotics (PCB, dieldrin, Hg²⁺)

1. Intestinal absorption of a polychlorinated biphenyl, dieldrin, and mercury (from HgCl₂) was measured in adult Northern bobwhites, Eastern screech owls, American kestrels, black-crowned night-herons and mallards in vivo by an in situ luminal perfusion technique.

2. Bobwhites, screech owls and kestrels absorbed much more of each xenobiotic than black-crowned night-herons and mallards.

3. Mallards absorbed less dieldrin and mercury than black-crowned night-herons.

4. Mercury absorption by kestrels was more than twice that in screech owls and eight times that observed in mallards.

5. Pronounced differences in xenobiotic absorption rates between bobwhites, screech owls and kestrels on the one hand, and black-crowned night-herons and mallards on the other, raise the possibility that absorptive ability may be associated with the phylogenetic classification of birds.