A partly cloudy, cool October morning with a light breeze makes for little action at the Hawkwatch International station in the Manzano Mountains. Field crew members and volunteers sit with binoculars, scanning the horizon for the dark profiles of southbound birds. They grumble at the resident red-tailed hawk cruising for a late breakfast. Repeat fly-bys aren't what they're after.

From late August to early November, every day weather permits, crew members and volunteers sit at this rocky promontory. It overlooks the valley south of Albuquerque, between the Manzanos and Mount Taylor, and boasts a view north to the Sangre de Cristo and Ortiz mountains.

They're well-positioned on a north-south corridor to count raptors migrating for the winter, explains crew lead and lead bander Jessica Taylor. The raptors sometimes fly by so close to the humans' perch they can see the wing bands marking a hatch-year red-tailed hawk—a bird making its first seasonal trip. Some species will ride the wind as far south as Argentina.

The site is part of a network tracking birds on the Rocky Mountain Flyway, and has been staffed since 1985. Each season, they count about 5,000 raptors in 18 species, and band about one-tenth of those they see. Three times this year, crew members caught birds already banded. One bird they netted had been caught by a Hawkwatch station in Wyoming 11 days prior. On their busiest day, they counted 350 birds.

Field crew and volunteers trade in nicknames for familiar geographic features on the horizon: the molar, the knob, the pink cliffs. That and shorthand like "two glasses up," meaning the space of two binocular views, help multiple spotters zero in on the same bird at a distance. They rapidly recognize familiar profiles of sharp-shinned hawks, Cooper's hawks, turkey vultures, Swainson's hawks, golden eagles and American kestrels—and can do so when those birds remain invisible to someone viewing with the naked eye.

Farther down the hill, other crew staff a blind equipped with nets and lures to catch a few raptors. The information gathered in a less than 10-minute stop helps raptor researchers understand more about migratory behavior and bird health. They're also collecting feathers, which hold DNA that can be tested for years, allowing future studies to use that data to investigate questions we haven't yet thought to ask.

Generally, Taylor says, "The most useful data Hawkwatch can get is trends in fluctuating populations."

That information has helped identify, for example, pesticides being used on farms in South America near where Swainson's hawks breed that was leading to a drop in their numbers. Recent years have seen the American kestrels making a similar decline, and now Hawkwatch International is collaborating with other research institutions to study what's causing their numbers to tank.

Raptor counts might also speak to broader trends.

"There are definitely birds that take the same migratory path year after year after year, but most raptors are fairly flexible with their migratory paths, which is really great for scientific purposes because we can study ecosystem health— 'Oh, well, they're not going over there. Why is that?'" Taylor says. With climate changing ecosystems, she says, "Hopefully, raptors will serve as an indicator to the bigger picture."

We've been talking and not all eyes have been on the sky, so when a field crew member walks up from a blind carrying two tin cans duct-taped together into one long tube, Taylor exclaims, "Hey, you guys got a bird."

A tuft of gray and white tail feathers protrudes from the end of the bird equivalent of a thunder jacket. Taylor cradles the cans and slowly extracts an adult male sharp-shinned hawk. It waits in her hand while she gives a tour of its rufous chest and slate blue back feathers and the "sharps" that define a raptor: its talons, beak and eyesight. She wiggles it, showing its head stays steady even as its body moves, allowing it to hunt while flying.

Taylor makes a point of letting volunteers release the birds—with kids, this smallest hawk can be placed in their hands, where it'll take a moment to recognize it's free and launch from their open palm.

"One of the best parts about the job is getting to pass a raptor off to somebody else," she says. "Most people are never going to be able to hold a bird like that in their lifetime."

So she talks me through sliding a finger along its stomach and then wrapping my hands around its sharp shins and bracing one finger in the warm, soft down of its stomach. It blinks its orange eyes at me, then I turn toward the valley and let it go with a little boost. Its wings hook on the air and it disappears beyond the oaks.

Visitors are welcome at the Hawkwatch International station. Directions are available at hawkwatch.org.