Aotearoa New Zealand’s unique parrot, the kākāpō, has developed two distinct color variations that may have helped it avoid detection by an apex predator that no longer exists, according to researchers. These findings were reported by Lara Urban from Helmholtz AI, Germany, along with colleagues from Aotearoa New Zealand’s Department of Conservation and the Māori iwi Ngāi Tahu, in the open-access journal PLOS Biology, published on September 10.
The kākāpō (Strigops habroptilus) is a nocturnal and flightless parrot that is native to New Zealand. Its population drastically dropped following the arrival of European settlers who brought new predators. By 1995, only 51 kākāpō remained, but with significant conservation efforts, their numbers have now grown to about 250. Kākāpō display either a green or an olive coloration, with both colors occurring in roughly equal numbers.
To explore how these color variations came to be and why they persisted even when the population was declining, researchers studied the genome sequences of 168 kākāpō, which encompassed nearly all living individuals at the time of the study. They discovered two genetic variations that together account for the color differences observed in the kākāpō. Using scanning electron microscopy, they found that the green and olive feathers reflect distinct wavelengths of light due to differences in their microscopic structures. The researchers estimated that the olive coloration emerged about 1.93 million years ago, coinciding with the rise of two predatory birds: Haast’s eagle and Eyles’ harrier. Their computer simulations indicated that the less common color would likely be harder for predators to spot, which could explain why both color variations have survived within the kākāpō population over generations.
The findings imply that the kākāpō’s coloration evolved in response to the visual predation pressure exerted by apex predators. This color variation has persisted even after these predators went extinct approximately 600 years ago. The authors suggest that understanding how kākāpō coloration originated could be significant for conserving this critically endangered bird species. Their research indicates that without human intervention, the variation in kākāpō colors might vanish within just 30 generations; however, they believe this would not be detrimental to the species in its current situation.
Co-author and conservationist Andrew Digby states, “By utilizing a comprehensive genomic library for the species, we have clarified how the present color morphs of kākāpō may be influenced by the pressures from extinct predators. Employing genomic analysis to gauge the significance of such traits is essential as we aim to restore the mauri (life force) of kākāpō by minimizing intensive management and reintroducing them to their original habitats.”
