They are endangered due to hunting and feral animals preying on their eggs.

由于被猎捕和野生动物取食他们的卵，他们已经成为濒危物种。

This subject of the checks to increase has been ably treated by several authors, and I hope in a future work to discuss it at considerable length, more especially in regard to the feral animals of South America.

增加支票的这个主题已经被几位作者巧妙地处理过， 我希望在未来的工作中进行相当长的讨论， 尤其是关于南美洲的野生动物。