This week’s animal comes courtesy of one of my old lab mates. I was chatting with her about science when she mentioned hearing about a poisonous bird.
My reaction: what??? A poisonous bird???? I need to know more!
It is with great pleasure that I introduce you to said poisonous bird, the pitohui. The name “pitohui” refers to several species of birds across a few different families found in New Guinea. The most poisonous ones are the variable pitohui and the hooded pitohui. I’ll be focusing on the hooded pitohui (Pitohui dichrous) here.
- Hooded pitohui are part of the Old World oriole family. These birds are not related to New World orioles (i.e., Baltimore orioles), but they do look very similar! They’re relatively small birds, about 9 inches long.
- Cooperative breeders
- We don’t know for sure that hooded pitohui are cooperative breeders, but we think they are. They live in family groups of multiple individuals, and more than two birds in a group have been seen defending nests from intruders and feeding the young chicks. This suggests that nesting parents may get help raising their young from older offspring or other helpers at the nest.
- Once upon a time (aka, 1989), scientist Jack Dumbacher was netting birds in New Guinea. He was getting a hooded pitohui out of his mist net when he got scratched and bit. Dumbacher probably thought, “hey, that sucks, but it’s not that big a deal. That’s field work for you!” So he thought nothing of putting his cut finger in his mouth. BUT THEN HIS LIPS AND TONGUE WENT NUMB. Coincidence? I think not!!
- Further research into hooded pitohui confirmed his suspicion: they were indeed toxic. His report in 1992 classified this toxin as the neurotoxin homobatrachotoxin. This is a derivative of batrachotoxin, the most toxic natural neurotoxin we know of and the same toxin found in Columbian poison dart frogs. Later bioassays found that most of the toxin is in the hooded pitohui skin and feathers. There is also some toxin found in the heart, liver, and skeletal muscles.
- …but how??
- Because there is poison both externally on their feathers and internally in their organs, these birds are probably not simply bathing in toxin. Instead, hooded pitohui likely gain their poisonous nature through the food they eat. In addition to their normal diet of figs, grass seeds, and some insects and invertebrates, hooded pitohui eat Choresine beetles. These little guys are both a) toxic, and b) have been found in hooded pitohui stomachs. Hooded pitohui appear to be able to sequester the poison from the beetles they eat into their feathers.
- …and why??
- There are currently two theories on why the hooded pitohui evolved to sequester these toxins from beetles. First, toxins may serve as a deterrent against predators. I personally don’t like when my food makes my mouth numb. The fact that the highest level of toxin is present in the hooded pitohui skin and feathers on their breast and belly also leads some scientists to suggest that the birds may be rubbing the toxins on their eggs to protect them against predators. Another explanation for the toxin is that it provides protections against parasites. Chewing lice prefer nontoxic over toxic feathers, and feeding on toxic hooded pitohui feathers reduces their life span. Of course, these two hypotheses are not mutually exclusive: hooded pitohui toxicity could protect them against both predators and parasites.
- First documented* poisonous birds
- Hooded pitohui are the first poisonous birds documented by science. However, the local people of New Guinea knew it was toxic for much longer. They purposefully do not hunt them, calling them “garbage birds” that are unpalatable. In situations where they need to eat hooded pitohui, they will prepare them very carefully, skinning them and rubbing the meat in charcoal. This is an example of Western scientists not listening to or acknowledging local wisdom. We would have known about hooded pitohui being toxic a lot sooner if we had asked the local people why they didn’t eat this bird.
I want to leave you with two thoughts:
First, scientists can miss a lot when they don’t listen to local people. Science as a whole benefits when we listen to and appreciate local knowledge.
Second, poisonous birds are super cool.