Hunted by invasive mustelids (which were introduced by humans to cull booming rabbit populations), kākāpō easily could have followed in the footsteps of the similarly ground-bound dodo, but surviving populations of the birds were moved to predator-free islands around New Zealand in the 1980s. Since then, attempts to reduce inbreeding and maintain genetic diversity in the minuscule population have been paramount.
“We show that the single male survivor from the mainland, Richard Henry, has more harmful mutations than Stewart Island birds,” said paper co-author Love Dalén, a researcher at the Centre for Palaeogenetics and the Swedish Museum of Natural History, in a statement. “Therefore, there could be a risk that these harmful mutations spread in future generations.”
Richard Henry the kākāpō was found in Fiordland in southwestern New Zealand, and his genetic diversity and virility were imperative in pulling the birds back from extinction. At the same time, though, Henry’s DNA harbors more harmful mutations than kākāpō from Stewart Island. (Richard Henry is named after a human who devoted much of his life at the turn of the 20th century to saving the species. Henry the human’s work has been resumed by a handful of New Zealand conservationists, many of whom co-authored the paper published today.)
The kākāpō’s genetic success story could be contrasted with that of the Isle Royale wolves, whose population of about 50 in 2011 plummeted to just two in 2016 after a new individual messed with the genetics of the already dangerously inbred group. A study of that situation, published last year in Evolution Letters, indicated that sometimes pushing high genetic diversity too quickly in a group with low genetic diversity can cause the population to collapse.
It’s also, perhaps, a warning for the kākāpō, as the bird is hardly out of the proverbial woods and, genetic diversity aside, has to worry about the predatory stoats and weasels that prowl its territory. The recent research will help to refine the breeding program approach, Dussex said, and new island populations could be established now that researchers have a better understanding of how all those in the current population relate.
If researchers manage to keep the kākāpō population genetically healthy, it’d be a big win in the battle for the animal’s survival. There are many threats ahead, but the portly green bird has a chance.