Thanks for the posts, henryp and Jack. I'd never heard of Haast's eagle. "Woodward's eagle" appears to have been similar but lived in California, probably before humans arrived.

That the author of the poem felt it necessary to add "A Fact" to the title suggests to me the possibility that the story was based on an account (probably fanciful) that he had been told as true.

Unlike eagles, vultures, of course, are scavengers.

The black vultures we have around here only weigh about five pounds, with a five-foot wingspan. They have shiny white feet and look pretty funny when they hop earnestly toward a road kill.