According to Jerry Davis with the Wisconsin State Journal, Hunters saw and killed fewer birds this Fall and Winter and West Nile Virus may be a contributing factor.
Initially, the heavy rainfalls were strongly suspected to affect the chicks during development. Now through samples and surveys in Michigan, Minnesota, and Wisconsin, game bird biologists are suspecting that the significant swings hunters experienced may be partially attributed to the West Nile Virus.
West Nile Virus is a disease found in birds which is spread by mosquitoes. Crows and Blue Jays are primarily affected. It has been found in all 48 contiguous states. It has existed in Wisconsin for about 16 years.
Hunters were anticipating a rise in bird populations. However, this year hunters found more infrequent bird flushes and were finding more grouse feather piles than in the past. In few cases, more birds were found sick and unable to escape hunting dogs.
While the record rainfalls still remain suspected as the initial culprit, the other cause could be the loss of birds to the West Nile Virus. With heavy rainfall, moisture enhances conditions for mosquitoes to transfer the virus. Any conditions which are good for the mosquito are good for the spread of West Nile.
The good news is the grouse nests usually contain 11-12 eggs and the populations can quickly recover.
Spring drumming counts are expected to continue in Wisconsin. The DNR and game bird biologist, Mark Witecha, will continue to discuss these issues which will impact populations.