Workbound early last Friday morning, the couple looked through the truck windshield down their long driveway and spotted what appeared to be a deer a hundred yards ahead. As the distance closed, it was plain they were looking at a cat, large and tawny. Mountain lion, concluded the Holden residents, as the feline disappeared into the woods.

On the previous Monday, there was a cougar sighting in Bucksport. It apparently has been a busy spring for the cats, once the UFOs of New England wildlife biology.

Not that long ago, people who believed they had seen one of the big cats and who were bold enough to announce the fact publicly were treated with some disdain by officials, who were convinced that the last Eastern mountain lion in Maine was the one trapped over in Somerset County in 1938.

In the past few years, however, a couple of things have happened.

The number of sightings has increased, many of them by people familiar with wildlife and the outdoors.

Since 1990, the Department of Inland Fisheries and Wildlife has logged 150 cougar or mountain lion sightings in its database. In addition to the Holden and Bucksport cat reports, both unconfirmed, there have been sightings in the last month or so in the north from Houlton, Down East from Lubec and Cherryfield and over in Lakeview Plantation.

Once officially dismissed as cases of mistaken identity by tourists and flatlanders, too many of these encounters have involved knowledgeable humans — people who wouldn’t be startled into adding 80 pounds to a fisher, for instance — to be anything but a big cat.

Their appearance may be due to possibilities other than the return of the indigenous Eastern cougar. That development is problematic for biologists who believe the animal extirpated (driven from its original range) or extinct.

The cougars spotted in Maine may be animals escaped from pet owners or the handful of breeding operations in Maine. A few cynics see darker possibilities, such as Greenies or environmental extremists deliberately salting the woods with endangered animals.

How the animals are getting here, whether by truck, loping down from New Brunswick (or maybe, a few have been here all along), is important to establish. As some biologists think, Maine may have widely dispersed cats of unknown but probably human-induced origin, and no breeding pairs. If that is true, it’s significant, because it means that protected mountain lions don’t have to be woven, for the moment, into decisions on development and land use.

The first step in determining where the cats have come from is to accept that they are here, and Maine wildlife officials now are taking the sightings seriously. That’s significant.

It also is important for people to know they may encounter cats out there, and to understand what is appropriate human behavior: Don’t shoot, except with a camera.