ISLE ROYALE, MI -- Researchers say they have found evidence of at least two wolves still roaming Isle Royale National Lakeshore.

Researchers posted photos of wolf footprints on the Wolves and Moose of Isle Royale website on Wednesday, Feb. 3.

The footprints were found in the slush of Lake Eva.

The wolves likely spent some time exploring an active beaver pond, judging by the footprints, the researchers said.

Related: One-eyed moose on Isle Royale enjoys predator-free life

The footprints were a welcome find, mostly because of the decline in the wolf population on Isle Royale over decades. Researchers, as part of an annual winter study dating to 1958, documented nine wolves in January 2014 but just three last winter.

The latest Wolves and Moose of Isle Royale Facebook post

In their heyday in 1980, wolves numbered about 50 on Isle Royale.

Then, there was a dramatic decline largely due to canine parvovirus. The population plummeted to 14.

Related: Biologist: Import wolves to Isle Royale ASAP

It rebounded to about 30 a decade ago, but then dropped again as the moose population - a food source for wolves - was on the decline.

In recent years, moose have been on the increase, climbing from 1,050 to 1,250 over the past two winters.

But wolves have shown a 90 percent decline since 2009.

The population is now at the lowest level since the study began in the late 1950s.

National Park Service researchers are working on a moose-wolf vegetation management plan and last summer sought public comment.