Disease takes toll on deer population

By Sarah Pridgeon

(Jeff Moberg photo) Mule deer doe and fawn.

White-tailed deer across the Black Hills are succumbing to epizootic hemorrhagic disease (EHD), an illness spread by biting gnats that generally affects bucks and fawns but is now hitting all age classes and both genders. Due to the broad area affected and the difficulty in locating carcasses, an exact mortality count has yet to be determined.
Though EHD is common in the Black Hills, particularly after long, dry summers when the first frost is delayed, the current outbreak may prove to be especially severe. The lack of water sources and rapidly drying ponds have caused deer to concentrate in areas where gnat populations are high, facilitating the spread of disease.
“It’s difficult to say how many have died, but it’s about the worst outbreak I’ve ever seen” says Sundance Game Warden Chris Teter. “The best gauge of numbers is the number of calls I’ve received, and it’s by far the most I’ve ever had. That indicates to me that this outbreak is pretty severe.”
EHD mostly affects white-tailed deer, but can also occur in pronghorn antelope, elk and mule deer, with variants appearing in bighorn sheep and some domestic animals. “Pets and humans are not a concern, but it can be found in cattle, though it will only give them a sore mouth and a bit of lameness,” explains Teter.
Symptoms of EHD include loss of appetite, extreme weakness and dribbling of blood-stained urine and feces, with affected animals usually dying in late summer and fall. The Game Warden office would like to be informed of dead or diseased animals to help determine how many deer have been affected and where they are located.
“An animal with EHD will initially look pretty depressed, show signs of fever and have a swollen head and neck,” says Teter, explaining how to spot a diseased deer. “They’re likely to be around water and have difficulty breathing. As the disease progresses they’ll appear lame and emaciated.”
The outbreak is widespread in Crook and northern Weston counties, but particularly severe just west of Sundance, he adds.
“It appears the die-off is widespread geographically and significant in some locations,” says Newcastle Wildlife Biologist Joe Sandrini. “The disease is endemic in the Black Hills and we experience some level of die-off most years. We’ll be able to get a better handle on this in mid-October when we do our deer trend counts in the Black Hills, and hopefully by then we’ll have had a good hard frost and the disease will have run its course.”
The carcasses of affected deer do not spread the disease and can be disposed of normally, says Teter. “There are certainly cases where private residents have no way to get rid of them, so we’re trying to help out where we can, but the carcass won’t be infectious as the disease can’t survive for very long after the host dies,” says Teter.
“The current EHD die-off really emphasizes how many factors come together to regulate deer populations in the Black Hills,” comments Sandrini. “The weather, disease, insect populations, predators such as mountain lions and habitat all interact, affecting each other and ultimately acting to increase or decrease deer production and survival. You just cannot point your finger at one thing and say it is solely responsible for trends in deer numbers.”
“Time will tell what winter will do to the spread of the disease,” says Teter of the long-term effects of the disease and its potential impact on hunting. “It’s dependent on the weather – we need a hard, biting frost to kill off the gnats.”
“Something like this current EHD epidemic can have a significant short-term effect, the results of which can impact hunting opportunity for several years, and unfortunately, this latest impact follows on the heels of the 2010-11 winter, which was most responsible for our current low numbers of deer,” adds Sandrini.
To report a dead or affected animal, call the Game Warden’s office on 283-1276.