MINNEAPOLIS — Minnesota’s gray wolf population appears to have grown by 25 percent thanks to more deer, the Department of Natural Resources said Monday.

The DNR’s 2016-2017 population survey estimated that Minnesota had about 500 packs and 2,856 wolves at midwinter after remaining relatively steady in the previous four surveys. The margin of error is plus or minus 500 wolves. The 2015-2016 aerial survey estimated the state had 439 packs and 2,278 wolves.

The higher wolf numbers are consistent with the growing deer population in the state’s wolf range, which grew an estimated 22 percent from 2015 to 2016, the DNR said.

“Changes in estimated wolf abundance generally have tracked those of deer over the past 5 years,” John Erb, the DNR’s wolf research scientist, said in a statement.

The annual count doesn’t include the population spike that happens every spring when wolf pups are born, the DNR said. While the population typically doubles for a while, many of those pups don’t survive until the next winter.

Gray wolves in parts of the lower 48 states have rebounded from near-extinction under federal protections imposed in the 1970s. Minnesota’s wolf population remains well above both the state’s minimum goal of at least 1,600 and the federal minimum goal range of 1,251 to 1,400. The U.S. Fish and Wildlife Service has long contended that wolves in Minnesota, Wisconsin and Michigan are no longer threatened, so hunting and trapping can be allowed under state control.

But courts have repeatedly rejected the service’s attempts to take the region’s wolves off the endangered list, most recently in August when an appeals court affirmed a lower court ruling from 2014. As long as the region’s wolves remain on the list, it’s illegal to kill them except to protect human life.

Hunting groups — and farmers and ranchers who want authority to shoot wolves that prey on their livestock — are pinning their hopes on legislation before Congress that would take wolves in the three states off the list and prevent the courts from intervening again. Several previous attempts to pass such provisions as stand-alone bills or as part of broader must-pass legislation have stalled out.