Hunters across north-central and northeast Montana reported seeing a large number of mule deer bucks in velvet this hunting season, according to Fish, Wildlife & Parks.
The reason may lie in the Epizootic Hemorrhagic Disease outbreak that affected deer in several areas across the region this fall. Although EHD is often fatal in white-tailed deer, mule deer can acquire the disease and, according to some studies, it may not always be fatal but instead affect testosterone production in bucks.
Without proper testosterone production, buck deer often have issues with the normal cycle of antler growth and may retain the antlers year-round. Several issues can cause testosterone production abnormalities — including disease, injuries, and old age — but the high number of velvet mule deer bucks seen this year pointed to other factors.
“We saw several mule deer in velvet brought by the Havre check station this year, and many more were reported by hunters,” said Scott Hemmer, FWP's Havre biologist. “We have seen this phenomenon happen in Montana after past outbreaks of EHD, and past research has suggested a possible association between EHD and antler irregularities in deer, and other abnormalities like hoof sloughing.”
A 2015 article in the Journal of Wildlife Management featured a study of mule deer in Colorado that suggested that the presence of velvet bucks in mule deer had some ties to EHD. Some of the velvet bucks that were sampled showed antibodies to EHD in their system. The EHD infection apparently caused lesions on their testicles, which then affected testosterone levels and ultimately antler growth.
EHD is an infectious, sometimes fatal virus that is usually spread by a virus-carrying gnat or midge. The disease mostly impacts white-tailed deer, often fatally, but also shows up occasionally in mule deer and antelope. Many of the animals affected with EHD lose their appetite, often are drawn to water, lose their fear of people, grow weak and typically die. EHD is not transmissible to humans.
EHD often occurs in central and eastern Montana in late summer or early fall, and outbreaks typically occur in river bottoms and large creek bottoms, likely due to higher concentrations of white-tailed deer and the insects that transmit EHD. These outbreaks often end shortly after a hard frost kills the insect vectors that carry the disease. The EHD outbreak was widespread in central and eastern Montana this year.
“I have talked to many hunters who had reports or questions about velvet or ‘stag’ bucks, and we saw a number of pictures shared on Facebook, as well,” added Glasgow biologist Drew Henry. “As I recall, we had high numbers of velvet bucks reported in other years that had EHD outbreaks, so there does seem to be a pattern.”
Marc Kloker, Region 6 information and education manager, visited with hunter Ron Evans about a velvet mule deer buck that he harvested this fall.
“The deer did not have normal testicles, but it did have the biggest body and is the fattest deer that we have ever seen,” Evans said.
Understandably, deer that have low testosterone levels don’t have the hormonal triggers to breed and are not burning up energy chasing does and scrapping with other bucks. This allows those deer to put on fat reserves, rather than burn them during the rut.
EHD does not affect humans, and any deer that has velvet is likely just fine to consume. However, if a hunter does see an abnormality in their harvest and they are unsure about consuming it, they can always contact their local biologist or warden.