In many endangered species, reproductive failure is a major barrier to recovery. The critically endangered kākāpō (Strigops habroptilus) exemplifies this challenge: 61% of their eggs fail to hatch, and of these 73% show no sign of development. Undeveloped eggs have previously been attributed to male infertility, but recent studies of non-threatened bird species suggest fertilisation failure is rare in the wild. The underlying causes of fertilisation failure and embryo death differ, so distinguishing between them is essential for effective conservation management. Here we show that the majority (72%, n=124) of undeveloped kākāpō eggs are fertilised, and combine this with conservation programme data on natural copulations, artificial inseminations, and paternity of developed eggs, to generate the most precise estimate to date of fertility in a wild population. We also demonstrate, for the first time in a wild bird, that artificial insemination results in greater numbers of sperm reaching the egg.

中文翻译：

---

极度濒临灭绝的kākāpō（Strigops habroptilus）的低孵化成功率是由早期胚胎死亡率而非不育引起的

在许多濒危物种中，生殖衰竭是恢复的主要障碍。极度濒临灭绝的kākāpō（Strigops habroptilus）体现了这一挑战：61％的卵无法孵化，而其中73％的卵没有发育迹象。未发育的卵以前曾归因于雄性不育，但最近对未受威胁的鸟类物种的研究表明，在野外受精失败的情况很少。受精失败和胚胎死亡的根本原因不同，因此区分它们对于有效的养护管理至关重要。在这里，我们表明未发育的kākāpō卵大部分（72％，n = 124）受精，并将其与有关自然交配，人工授精和发育卵的亲子关系的保护程序数据结合起来，以生成迄今为止最准确的野生种群生育力估计值。我们还首次证明了在野生鸟类中进行人工授精会导致大量精子到达卵子。