BOSQUE DEL APACHE NATIONAL WILDLIFE REFUGE, N.M. — Dozens of photographers and birders stood at the bank of the shallow pond, patiently waiting in the biting cold for the main act to take the stage.

Suddenly, as if trigged by an unseen instinctual cue, hundreds of snow geese and sandhill cranes began calling to each other as the sun peeked over the desert horizon.

As the sun went higher, the cackling grew louder and the birds took flight from their watery roost, with the cacophony of wild calls and beating wings drowning out the repetitive clicks of the cameras.

Bird and wildlife enthusiasts have flocked to the 57,000-acre Bosque del Apache Nation Wildlife Refuge in southern New Mexico each November for the past 20 years for the Festival of the Cranes, which celebrates the return of thousands of sandhill cranes to their winter habitat along the Rio Grande.

Preliminary estimates show this year's festival drew more than 9,000 visitors from around the world, said Leigh Ann Vradenburg, executive director of the Friends of the Bosque, a nonprofit volunteer group that puts on the festival in conjunction with the refuge and the city of Socorro.

"Each year attendance has gone up. It's now at the highest it's ever been," she said. "We've been able to retain a lot of people and there's word of mouth that goes on, bringing in more visitors."

Refuge manager Tom Melanson said the festival began in 1988 as a one-day event aimed at bringing awareness to wildlife at the refuge and creating a bond with surrounding communities.

Most of the cranes that stop at the refuge begin their migratory journey from breeding areas in the northern United States. Some head down from Alaska, Siberia and Northern Canada.

The cranes use what's called the Rocky Mountain flyway as they make their way to warmer wintering grounds in southern New Mexico and Mexico, said Colin Lee, wildlife biologist at Bosque del Apache.

Although visitors can view migratory birds from October through February at the refuge, the weeklong festival includes tours, workshops and exhibits. Tom Harper, festival coordinator, described it as "a friendly, relaxed event for everyone."

London residents Andrea and Wright Robinson and their two young sons attended this year's festival. The Robinsons said they wanted to expose their children to birding and the beauty of nature.

"The boys love hiking, and my son Myles is a big naturalist. He wants to be a zookeeper when he grows up, so we decided to introduce him to the real thing," Andrea Robinson said. "We heard there could be 9,000 birds in one flock ... and we can't see that where we come from."

One element that makes the festival so unique is the large crew of volunteers that interact with visitors, Melanson said. The volunteers come from all over the country to spend their time rubbing elbows with fellow wildlife lovers.