Cameron Gallon took off toward the giant white bird in a Kiwanis Lake pine tree.
"Is that a neck? Look at his neck!" Cameron, 11, yelled to classmates.
Spotted, the great egret left its perch to deliver the sticks it had collected to a female egret building the ornithological couple's nest.
Back and forth the egrets flew across the water as sixth-graders from Devers K-8 school followed through the magnified views of telescopes and binoculars.
A little less obvious but just as cool were the black-crowned night herons napping in the upper branches of trees surrounding the lake.
"I see it! I see it! Right there!" the students called to each other as they jockeyed for position under the motionless herons.
This is how dozens of York City students spent their Monday. And they didn't have to leave town to do it.
Kiwanis Lake is one of the few places in Pennsylvania the egrets and herons call home. The area was named an Important Bird Area years ago.
The rookery's urban location makes it even more special to groups like the Pennsylvania and York Audubon societies, which hosted the Devers students Monday.
Bird-watching was just part of the field trip. Divided into groups, the students also cleaned up trash along Willis Run, removed invasive plants and learned how to fish.
"The kids are so receptive, so interested," said Tish Swam, a York Audubon member who helped the students spot egrets nesting across the lake.
Alice Frick, conservation chair for York Audubon, said the group has been planting trees around the lake for years to encourage egrets and herons to nest.
"The birds are coming back," she said.
The goal of Monday's outdoor lesson is two-fold, said Amy Weidensaul, director of education and engagement for Audubon Pennsylvania.
Students need to learn about the natural environment, particularly the way water quality is connected to the health of its surrounding environment, she said.
But York City students also need to learn that "York is a really important place for wildlife," Weidensaul said.
Earlier Monday, the group saw bald eagles, belted kingfishers, Cooper's hawks, red-tailed hawks and - of course - lots of mallard ducks.
"And we were just right here," Weidensaul said.
- Reach Erin James at firstname.lastname@example.org.