Are there any poisonous birds?

The short answer, which comes as a surprise to many, is "yes." Almost everyone knows of poisonous spiders, insects, fish, and snakes. For a long time, people thought that there were just two poisonous lizards -- the Mexican beaded lizard and the Gila monster -- but it has been discovered recently that many lizards (including some kept as pets) have poison in their saliva, just no good way to get it into a person via a bite. Australia has a weird mammal -- the duck-billed platypus -- whose male has a poison spur on each foot.

The discovery of poison in birds goes back to 1898 when Jack Dumbacher , then a graduate student at the University of Chicago, was studying birds in Papua New Guinea. He noticed that scratches from the pitohui bird caused a numbness that made him think of poison.

Pitohuis are referred to by the locals as "rubbish birds" due their persistent and unpleasant smell, but nobody had ever imagined they might be toxic. Further investigation revealed that several species of pitohuis are poisonous, to varying degrees, with poisons called "batrachotoxins" in their feathers.

These toxins were previously known from poisonous frogs -- frogs used by the indigenous people of Colombia to make blow darts -- and it's possible the frogs may in turn get it from eating poisonous insects, but the jury is still out on that one.

Dr. Knowledge is written by physicists Stephen Reucroft and John Swain, both of Northeastern University. E-mail questions to drknowledge@globe.com or write Dr. Knowledge, c/o The Boston Globe, PO Box 55819, Boston, MA 02205-5819. Include your initials and hometown.