The digital cameras, which have night vision, are strapped to trees at knee height and away from trails. A small plastic disc that smells like cheese serves as a lure. Activated by movement and heat, the cameras are left to do their work for eight-week stretches. Then the researchers retrieve the images.

Image A motion sensor camera captured coyotes in Pelham Bay Park in the Bronx in December 2013. Credit... Gotham Coyote Project

By far the most fruitful territory has been the Bronx. In Pelham Bay Park and Van Cortlandt Park, the borough’s two largest parks, which both border Westchester, the cameras have captured images of coyote pups emerged from their dens. Residents in the Riverdale and Pelham Bay neighborhoods say they have heard the animals howling.

“We see puppies chasing butterflies in front of the camera,” said Chris Nagy, the director of research and land management at the Mianus River Gorge in Bedford, N.Y., who founded the coyote project with Mark Weckel, a conservation biologist who is the manager of the Science Research Mentoring Program at the American Museum of Natural History. “We see pairs goofing off and rolling around and playing. Sometimes you see them sniffing at the camera.”

“The finding of pups at new places is the key, but seeing them in action is really good,” he said. “They are behaving pretty naturally because the family of coyotes doesn’t know we’re taking pictures.”

The most interesting development came last year when a camera in Ferry Point Park, at the foot of the Bronx-Whitestone Bridge, recorded the first known instance of breeding so far south in the borough.

In 2012 and 2013, the camera in Ferry Point Park picked up evidence of coyotes. Last July, there were pups.