MADISON, Wis. (AP) – A new survey shows Wisconsin’s ruffed grouse population has declined slightly.  The Department of Natural Resources says the survey shows the population decreased 9 percent between 2012 and 2013.  The DNR, U.S. Forest Service, tribal staffers and volunteers have been conducting a roadside survey to monitor the number of breeding grouse since 1964. Surveyors begin 30 minutes before sunrise and listen for the “thump, thump, thump” sounds drumming male grouse produce at 10 different stops.        The number of drums surveyors heard per stop in 2013 was down 9 percent statewide from last year. DNR wildlife ecologists say the loss of dense, brushy areas grouse need for cover has contributed to the decline.