Whose backyard is it, anyway? When a wildlife camera is on duty, with its heat- or motion-triggered shutter at the ready day and night, the answer can be startling.

Sally Naser calls the animals recorded on the dozens of cameras she monitors for The Trustees of Reservations in Massachusetts “our wildlife neighbors.” At home, in our gardens, we may call them cute — or our herbivorous enemies. But more often than not, we don’t see them.

“There is wildlife all around us, whether you live deep in the woods or on an urban edge,” said Ms. Naser, the conservation restriction stewardship director for the Trustees, the nation’s first preservation and conservation nonprofit, with more than 26,000 public acres and another 20,000-plus private acres under conservation easements. “In back country and in front country, if you want to get this window into the wild, it’s out there for the camera to record.”

Instagram feed and Facebook page). But you never know, especially when it comes to animals more comfortable moving about after dusk, including the opossum, weasel and fox.

Get ready to be informed and surprised, like the family who spent 40 years in a home before realizing they shared the yard with a bobcat — something they would never have known without Ms. Naser’s camera.

Trail Cam Pro website make a good starting point for research.

Animal Diversity Web from the University of Michigan Museum of Zoology, can be useful.

Water of any kind — even a small backyard water feature — is a magnet for birds and mammals. In wilder areas, beaver dams are among Ms. Naser’s favorite spots for a camera. She calls them “wildlife superhighways.”

Edge habitat — brushy areas where animals can stay close to cover — are also lively. Stone walls are popular with predators, including barred owls; not coincidentally, they are also a favorite hide-out for rodents. A backyard apple tree with fallen fruit or an oak with its acorns are productive autumn locations, inviting everyone from squirrels to deer, blue jays and turkeys.

As for the best height to position the camera, that depends on the target species. Ms. Naser puts it this way, with a laugh: “Knee height or below for most wildlife, and shoulder to head height for moose.”

For the best images and to widen the field of view, position the camera at a 45-degree angle to the target area, and aim it parallel to the ground. A stick can be used as a shim behind the unit.