The Poison Bird – Hooded Pitohui

The hooded hitohui (Pitohui dichrous) of Papua New Guinea is one of the world’s first and only documented poisonous birds. It was discovered to be toxic during a 1989 study of birds of paradise by American ornithologist John (Jack) Dumbacher. He and his team had mist nets set out to catch birds of paradise, but inevitably, other birds were caught in the nets as well. Some of these birds were hooded pitohuis, which would bite and scratch defensively when being extracted from the mist net. Dumbacher got a bite from one of the birds on his finger that started to sting, so he decided suck on the cut to clean it. After about a minute, his lips and tongue started to tingle and burn. This happened to several other volunteers as well so the team wondered if the pitohui was the cause. When more pitohuis were captured, Dumbacher took a feather and put it directly on his tongue, finding that the burning and tingling effects could last for hours. When he returned to America, Dumbacher took some feathers to chemist John Daly at the National Institute of Health. By 1992, Daly discovered that the feathers contained batrachotoxin. It is an extremely powerful steroidal alkaloid poison that is largely neurotoxic, and even relatively small doses can lead to paralysis of all muscles, cardiac arrest, and then death. This is the most toxic natural substance known and is also present in the secretions of several poison dart frogs of the genus Phyllobates (most famously, Phyllobates terribilis – the Golden Poison Frog).

At first it was not known how this bird acquired such a potent toxin, but locals of New Guinea were asked what they knew about hooded pitohuis and relayed their observations. Pitohuis often catch and eat small and colorful Choresine beetles from the Melyridae family. The same toxin has previously been found in these beetles, which are also known to be preyed upon by Phyllobates poison dart frogs. The striking orange and black feathers of the hooded pitohui are another indication of its toxicity. Many poisonous and venomous animals are brightly colored to warn potential predators that they are very dangerous and not to be messed with. This is called aposematic coloration. Any animal unlucky enough to catch a pitohui would quickly learn to stay away when it sees those colors again. Of course, the bird has not always had this defense. First it had to evolve to cope with the poison itself before being able to incorporate the toxin as part of its own defense. It is likely that the first pitohuis that fed on melyrid beetles only ate a few at a time, slowly building up a resistance to batrachotoxin over generations. This toxin has been found in not only the bird’s feathers, but also its flesh.

This amazing, colorful bird just goes to show that even the most seemingly harmless animals can have alarming tricks up their sleeves.

References:
1. Dumbacher, John P., et al. “Homobatrachotoxin in the genus Pitohui: chemical defense in birds?.” SCIENCE-NEW YORK THEN WASHINGTON- (1992): 799-799.

2. Dumbacher, John P., et al. “Melyrid beetles (Choresine): A putative source for the batrachotoxin alkaloids found in poison-dart frogs and toxic passerine birds.” Proceedings of the National Academy of Sciences of the United States of America 101.45 (2004): 15857-15860.

3. “Jack Dumbacher.” California Academy of Sciences. N.p., n.d. Web. 24 June 2015. <http://www.calacademy.org/explore-science/jack-dumbacher&gt;.

Photo Links:
1. http://img2.panamericana.pe/slideshow/1392751307845.jpg

2. http://blogs.scientificamerican.com/guest-blog/files/2012/08/Choresine-and-Pitohui.jpg

Advertisements