Beloved Kakapos Won’t Be Saved Easily

A new break-through in kakapo conservation highlights the intricacy of conservation practices and the relevance of ecological and evolutionary research

At this point in time, 201 kakapos (Strigops habroptilus) are left in the world. Endemic

to New-Zealand, these flightless, muppet-faced yet endearing parrots as Sarah Feldberg at National Geographic describes them, are critically endangered and in desperate need of conservationist attention. We are doubly responsible and credited with their decline, as kakapos have historically struggled to both escape human-introduced predators in New-Zealand and adjust to the current speed of climate change. Unfortunately, helping kakapos is proving to be a mammoth task. Firstly, although kakapos can live up to the age of 80, they only breed every 2 to 4 years, requiring a threshold weight of 1.5Kg to breed. Their weight is highly dependent on when rimu trees produce enough fruit for them to consume. When reaching this threshold, they are also limited by their low chances of finding mates as individuals become More and more scarce. To top it off, when kakapos do breed, only half of their eggs are fertile and go on to hatch into healthy chicks. This is down to the high level of inbreeding that has resulted from limited choices of partners.

Nevertheless, their historic importance to New-Zealanders and general popularity as a charismatic species have led to grand kakapo conservation efforts. Numerous interventions have been introduced including: the major relocation of kakapos to a predator-free island, supplementary feeding, lab-controlled hatching and artificial insemination (to limit inbreeding).

A problem that conversationists did not initially consider however is ‘sex-allocation’ - defined as the allocation of more resources to the production of sons over daughters by their mothers when said resources are abundant. It’s a phenomenon that is frequently neglected in conservationist efforts yet of grave importance as it can lead to the creation of sex-biased chick populations. Deviating from a 50:50 sex ratio aggravates the situation for kakapos, making it harder for conservationists to repopulate the species and prevent inbreeding. In birds, over-feeding is often at the root of the problem. Michael Clout from the university of Auckland and his co-authors wrote in Ecology letters that, following supplementary feeding conservation efforts, 70% of resulting kakapo offspring were male. If the well-meaning regime continued as it was, the population recovery time was predicted to take up to 109 years. This realization led to careful, theory-informed changes in the feeding regime applied to kakapos.

Underweight females are now supplemented up until they reach 1.5Kg (the breeding weight threshold) but importantly, the feeding then stops unless females dip under the breeding threshold once more. Once eggs are laid, supplementary feeding then continues to aid egg and fletching growth. In doing this, Bruce Robertson from the university of Ontago and his colleagues solved the dilemma. Once the regime was applied to kakapo mothers, the sex ratio of chicks returned to 50:50.

The field of sex-allocation was initially blue-skies research (a domain with no applications) developed by ecologists. This Kakapo case-study elegantly exemplifies a real-world application of the theory as well as its relevance in conservation practices.

As many dwindling species are conserved using supplementary feeding,

lets hope the kakapos instruct us all on the importance of preventing sex biases, intricately catering conservation efforts according to the focal species ecology and making use of theory from neighboring fields!

"Kakapo chick" by Department of Conservation is licensed under CC BY 2.0