Hard winter for mule deer
2011 fawn survey
Volunteers inspect a mule deer carcass to determine its age and
sex while conducting a past deer mortality survey near Pinedale. Photo by Mark Gocke, Wyoming Game and Fish Department.
45-75% fawn loss in Sublette and Wyoming Range herds
by Wyoming Game & Fish
May 30, 2011
With the snow finally receding on mule deer winter ranges in western Wyoming, wildlife managers with the Wyoming Game and Fish Department are getting a chance to assess winter impacts on the herds and the preliminary results are not good.
"We suspected this winter would be especially hard on the fawns and older-aged animals and it has been," said Pinedale Wildlife Supervisor, John Lund. "We’re documenting some of the highest mortality we’ve had in several years."
Each year, biologists and game wardens count the number of mule deer does, fawns and bucks both in December and then again in April or May to see how those ratios, particularly the numbers of fawns to does, change over the winter. Preliminary results are showing winter losses of between 45% and 60% of mule deer fawns in the Sublette deer herd, and as high as 75% fawn losses in portions of the Wyoming Range herd. Managers note that these are some of the worst losses seen in the Wyoming Range herd since 1990, when such records started being kept. Biologists also point out that these numbers are an absolute minimum as some deer will continue to die from depleted reserves even though some vegetation has started to green up.
Although the change in fawn ratios gives managers an indication of fawn loss, it doesn’t necessarily show the overall losses, including adults. To get a better picture of overall winter losses, Game and Fish also conducts deer mortality surveys enlisting as many volunteers as possible to survey traditional winter ranges and document all the deer carcasses they can find. Such surveys recently conducted in the Sublette herd showed that about one-third of all mortalities were adult deer. Surveys in the Wyoming Range documented over 400 deer carcasses total, which was the highest number recorded, since the early 1990s.
"Clearly this has been a hard winter on our deer herds, and especially the fawns," said Lund. "We’re basically going to be missing the majority of this year’s fawn crop and it will probably be noticeable for the next few years. Hunters should expect to see fewer deer this fall and even a few years out when this year’s fawn would be that mature buck most hunters are looking for."
Anticipating the winter loss, local Game and Fish personnel proposed more conservative deer hunting seasons in the Sublette mule deer herd starting this fall. Managers proposed reducing the overall season length three days taking away the last weekend of the general season and eliminated the "any deer" season that was offered in some hunt areas. The Game and Fish Commissioners endorsed those seasons at their recent meeting in Casper.
"There are a number of challenges these deer herds are facing, such as hard winters, drought, continued habitat fragmentation and so on, but we continue to work with our partners to try and counterbalance those negatives to the extent possible," said Lund. "We have more habitat improvement projects on the slate and WYDOT is currently making modifications to highway 191 west of Pinedale which should significantly reduce the number of migrating big game animals getting hit by vehicles."
For more information people may contact the Jackson Game and Fish office at (307) 733-2321 or 1-800-423-4113 (in-state) or the Pinedale Game and Fish office at (307) 367-4353 or 1-800-452-9107 (in-state) during regular business hours. Additional information can be found at the Game Fish Department’s regional news web page at: