It’s 5:30 a.m. in the tree farms outside Urbana, but the birds have been up for an hour already. I sip my coffee, putting on rubber boots that will be little help against the dewy, waist-high grass.

A couple of brown birds sit on telephone wires above me, and I have a feeling I am being watched. These are brown-headed cowbirds, which lay their eggs in other species’ nests and then let the nest’s owners raise the offspring.