ST. PAUL (AP) - A survey by the Minnesota Department of Natural Resources finds ruffed grouse drumming counts this spring unchanged from the year before.

DNR grouse project leader Charlotte Roy says this follows a significant increase of 34 percent from 2013 to 2014.

Roy says officials suspect the cold, wet spring of 2014 may have hurt grouse production. There was also comparatively little snow last year for roosting, which may have influenced grouse survival over the winter.

Drumming is the low sound produced by male grouse as they beat their wings rapidly and in increasing frequency to signal the location of their territory. Drumming displays also attract females that are ready to begin nesting.

Compared to last year's survey, 2015 ruffed grouse survey results showed no statistical change in all regions of Minnesota.