Contents

30 October 1992
Vol 258, Issue 5083

About The Cover

Several species of pitohui, songbirds endemic to New Guinea, contain the potent neurotoxin homobatrachotoxin, apparently as a chemical defense against predators. Chemical defenses have been known to be used by many organisms but not by birds. See page 799. As a possible antipredator adaptation, certain races (top) of the variable pitohui (Pitohui kirhocephalus) mimic the plumage of the hooded pitohui (P. dichrous; bottom), which contains the highest concentration of toxin. A nonmimetic subspecies of the variable pitohui is in the center. [Illustration: John C. Anderton]