The kākāpō parrot (Strigops habroptilus) is the only flightless parrot in the world and possibly one of the world’s longest-living birds, with a reported lifespan of up to a century. It is a nocturnal, herbivorous, sexually dimorphic bird, with a low basal metabolic rate and no male parental care.
Currently, this species is critically endangered, consisting of a total known population of only 249 individuals which are confined to four small islands off the coast of New Zealand that have been cleared of predators. Factors such as infrequent breeding, high infertility, and low hatching success significantly hamper conservation efforts and, while habitat restoration and predator control are useful strategies for enhancing survival, the problems related to reproductive output are those that limit recovery the most.
Now, a new study published in the journal PeerJ Life & Environment has provided critical insights into the factors that affect the fertility of the kākāpō in order to improve conservation management efforts. These findings highlight the need for a balanced approach to conservation management that takes into account both the short-term benefits and the potential long-term negative impacts of hand-rearing and other management strategies.
According to the experts, hand-rearing – in which animals are raised in captivity by humans – should be limited as much as possible for males, since although it undoubtedly increases chick survival, it reduces clutch fertility. Thus, hand-rearing appears to affect copulation behavior in males more than females, in accordance with imprinting behaviors found in hand-reared male but not female parrots.
In addition, population densities should be maximized so there is a sufficiently high number of males at leks to ensure adequate mate choice for females, but the male:female sex ratio is kept only as high as the habitat can efficiently support. Finally, artificial insemination should be continued in order to ensure sufficient sperm competition, while increasing founder representation.
These findings emphasize the critical importance of collecting comprehensive longitudinal data and assessing similar effects of hand-rearing and sex ratios in other endangered bird species.
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