It's dawn in late January, near Marfa, and the grasslands on Mimms Ranch are radiant, swaying like a thick, golden mane in the sporadic breeze.

Across the plateau treks a 20-person team – scientists, birders, volunteers.

A pair holding radio antennas leads the way. Soon, they locate a signal. Technicians swiftly raise a net – and the rest of the group moves into formation, creating a semicircle.

Quietly, they advance, closing in on the signal's unseen source.

Suddenly, it rises, in a flurry: a tiny grassland sparrow. The bird darts skyward – and then flies just outside the net.

It's a narrow miss. But as the morning continues, this team – led by Alpine's Borderland...