Pinedale Mule Deer Population Declines

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A new report by Western Ecosystems Technology Inc for the Bureau of Land Management shows that the mule deer herd that winters on the Pinedale Anticline in Wyoming has declined 36% in the last nine years. The Pinedale Anticline is one of the largest natural gas fields in North American and has seen significant drilling and energy development over the last decade.

The Sublette Examiner has a detailed article on the report and its upcoming BLM presentation.

The study postulates three reasons for the Mesa's mule deer decline between 2008 and 2009.

The first is a series of mild winters that might not have pushed the deer all the way to the Mesa. The second is a new law prohibiting antler gathering before May 1. The report says the new law reduced winter ATV traffic in the Ryegrass area; previous traffic could have pushed mule deer to the Mesa. The last cause could be the Mesa's natural gas development, particularly after the 2008 ROD allowed energy companies to drill during winter months.

“It is possible,” the study says, “that this increased winter disturbance affected fawn survival or adult reproduction.”


WishIWasHunting's picture

Good article

After reading this article, I have to say that I am glad they are trying to keep an eye on situations like this, but I think the numbers are possibly misleading and it might be a bit of an overreaction.  As mentioned in the article, weather patterns may have influenced migration into the area.  Also, change of rules regarding snowmobile use in a nearby area also may have influenced migration.  Unless Wyoming Game & Fish is better than CDOW at population counts, I wouldn't put too much weight in the population counts to begin with.  Depending on which count methodology they are imploying in this area, there can be a large statistical difference in the counts themselves.  Finally, it sounds like they are looking at one migratory herd.  I would be more concerned if total mule deer numbers also including the surrounding area also showed an identical decline. 

I saw keep an eye on the situation.  Make sure the oil and gas workers are not misbehaving (harassing the wildlife, poaching). 

cscott711's picture

I find it interesting that

I find it interesting that all three possibilities for a decline in numbers are related to the human interaction and there is no mention of disease, predators (wolves), or over hunting.  If the decline in that specific area is simply due to humans not pushing the deer to the mesa, then it really isn't a concern that I can understand.  The deer are still in the around, they just don't migrate to that specific locale due to human pressure or lack there of.  I would be more concerned if the potential reason for decline was one of the possibilities I mentioned above.

Ca_Vermonster's picture

I know they have been

I know they have been studying mule deer populations across the entire west for the last decade, because they seem to be declining everywhere.  Hopefully it's a problem they can identify and rectify.

CVC's picture

I have heard that the mule

I have heard that the mule deer populations have been declining but I haven't heard why.  You mentioned that they are studying it, are there any preliminary theories for the decline?  Is it competition for range with whitetail or ther species?

CVC's picture

I am glad that they are

I am glad that they are monitering it, but can't help but wonder if fluctuations in deer populations are just normal occurrances that will go up and down periodically.  How accurate are their methods for counting herd sizes too.  Regardless, I think getting a jump on the situation and taking proactive steps to manage and protect the herd population is the right thing to do.  Wyoming depends on their game population and I am sure they will do what is necessary to protect it.  It is a valuable resource just like their oil and gas.

ecubackpacker's picture

I would agree the game dept

I would agree the game dept gets a lot of revenue from hunters hunting mule, but to compare the mule deer as a resource to oil and natural gas....that's like comparing gold to gold dust. There is no comparison of the two. The deer bring in revenue but nothing in comparison those natural resources.

I think their explanations tell the story why the deer aren't there on the Mesa but not necessarily a decline in deer numbers per say.

Tricky Issue

I just returned from a mule deer and antelope hunt in the Pinedale area.  We hunted deer in the Wyomng range just west of Pindedale and I can only complicate the subject by suggesting that we did not see many deer, but since we were hunting in record high temperatures when the deer were clearly timbered up I don't believe that what we saw in any way suggests a fundamental population problem.

My hunting partner was able to harvest a 24-inch mule deer buck that we viewed as an animal that would represent the low end of a shooter for the area - but it was a last day buck and the only mature animal we saw in six days of hunting.

The three potential reasons listed by the study are very diverse and may carry little relevance to the actual health and population of the herd.  I genuinely hope the BLM, USFS and WY Department of Fish and Game take this seriously as this is a top shelf mule deer destination for the self guided hunter in an area that has spectacular country.  I look forward to the presenation and to a better understanding of the possible decline of the herd.  I intend to return to the area in 2013-ish and would hate to have to change my plans.

gatorfan's picture

Is this correct?

The way it is written, I think it is fairly easy to assume that something major happened to the migration between 2008 and 2009.  The numbers had been rising between 2005 and 2008 at a rate of 33%.  So, to see a drop of 1762 animals in one year, you would think it would be easy to eliminate some of the possibilities.  I would, however, like to see the numbers for 2006 and 2007 in order to see if there was any sort of pattern.  Easy winters means less migration, right?  Fewer ATVs chasing animals around during easier winters means the deer are more inclined to stay where they were, right?  Easier winters, fewer ATVs, and the introduction of increased human activity in the "normal" wintering range means fewer numbers of deer in the area of concern, right?

"The WEST report says the 2005 population was 2,894 deer. In 2008, it reached a high of 3,850 but in 2009, the number fell to 2,088 – a 28-percent decrease. What’s more, the 2009 population plummeted by 1,700 animals."


2008-3850 (+956 or 33% from 2005)

2009-2088 (-1762 or 46% from 2008)

Interesting article nonetheless.