And now I've hit two other snags.

1. The Internet Archive won't let me print the poem. And it and Noteworthy won't co-exist side by side. (tiled)

2. I'm a birdwatcher; I want people to observe and respect the birds. The poem refers to the linnet as green. I googled linnet, and the linnet is not one whit or by an stretch of the imagination, green.

I'm pleased to discover that the linnet must be a cousin to our "red finches," whether purple finch, house finch or Cassin's finch. They are small, tan birds with various amounts of rosy-red on them, and they are active and vociferous singers.

The species in my neighborhood is the house finch (known locally as raspberry sparrow), and when it 'sings' it sounds like it's talking.
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When MacManus wrote this:

"..calling, calling, calling. Why leave this happy, happy wood..."

I think he was trying to imitate birdsong in poetry, and he wanted a melody (if any) to imitate birdsong, too.