Evrim Yazgin
Cosmos science journalist
Genetic analysis has revealed why New Zealand’s native flightless parrot, kākāpō, are just as likely to have green- or olive-coloured feathers.
Kākāpō (Strigops habroptilus) is a nocturnal bird which experienced severe population decline after the arrival in New Zealand of Europeans who brought with them new predators. By 1995, just 51 birds remained. Conservation efforts have seen the population rise to about 250 birds.
The parrot’s ancestors emerged on the ancient continent of Zealandia at the end of the ‘Age of Dinosaurs’ when the continent split from Gondwanaland.
In the millions of years since, colour variation has evolved among kākāpō.
The new research, published in PLOS Biology, sought to explain different kākāpō colours. Genome sequences of 168 individuals were analysed.
Olive colour first appeared about 1.93 million years ago coinciding with the evolution of 2 predatory birds: Haast’s eagle and Eyles’ harrier. Both birds are believed to have become extinct soon after the arrival of Māori to the archipelago about 600 years ago.
Haast’s eagle is the largest eagle known to have existed, weighing 10–18 kilograms.
Scanning electron microscopy showed that green and olive kākāpō feathers react differently in the light.
Computer simulations suggest whichever colour was rarer would have been less likely to be detected by predators. This may explain why both colours have persisted in kākāpō.
The authors of the study say that understanding the emergence of the different colourations may help in the conservation of the critically endangered species. Without intervention, they show that kākāpō colour variation could be lost in just 30 generations.
“By using a comprehensive genomic library for the species, we have explained how the current colour morphs of kākāpō might be a result of pressure from extinct predators,” says co-author Andrew Digby from New Zealand’s Department of Conservation.
“Using genomics to understand the current significance of such characteristics is important as we seek to restore the mauri (life force) of kākāpō by reducing intensive management and returning them to their former habitats.”
