Professor Documents Bighorn Decline

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The bighorn sheep is perhaps the most iconic North American big game animal and many hunters aspire to make a sheep hunt the pinnacle of their hunting careers. Unfortunately bighorn population counts have been in free-fall for some time. Dr. Teresa Zimmerman of Chadron State College documents the fall of the bighorn in this article.

Zimmerman, who studied bighorn sheep at Badlands National Park for her doctoral dissertation, noted that bighorns and humans have coexisted for about 30,000 years, but major declines have occurred in just the past 150 years. During that period, the bighorn population in North America has deteriorated from an estimated high of 4 million to a low of 22,000, she said.

As the article notes, bighorns are particularly susceptible to pneumonia transmitted from domestic sheep populations. Bighorn pneumonia can be rapidly spread once it is contracted within a herd population. Recently Montana wildlife officials announced that they were not able to stop a pneumonia outbreak in the "Anaconda" herd of bighorns.


ecubackpacker's picture

It's a sad situation for sure

It's a sad situation for sure when you do all you know to do to help these animals but it isn't enough.

The problem I'm having is the CODOW is allowing ranchers to graze their domestic sheep along side the bighorn sheep in wilderness areas. Why would they allow this to happen when they know the possible hazards to the bighorns presented by the close proximity to domestic sheep?  How does it remain a wilderness area if the domestic sheep are destroying the natural food source for the bighorns and other animals of the wilderness? They dessimate an area when they graze through it.

It's unbelieveable that they would allow this to continue!  

CVC's picture

The only answer that comes to

The only answer that comes to mind is politics and influence.  I can't believe the DOW would allow this if they weren't pressured to do it.  I could be wrong, but it just makes no sense to do unless you're a sheep rancher and want to expand your grazing area.

ecoroamers's picture

Bighorn pneumonia outbreak

Very beautiful and impressive animals, and yes,they are truely the kings of their domains.  Its a shame that a disease that can be somewhat prevented in other ruminants cannot even be slowed down in these animals.  Being an airborne transmitted illness that comes from domestic sheep herds it is virtually impossible to curtail without moving the sheep farming industry more than 10, 20, or 100 miles from these magnificent heards, or is that even enough?  I for one do not agree with the Montana Fish and Wildlife's choice on killing 44 of the 300 head of Anaconda sheep they "thought" might be infected, when they now say they really cannot tell the difference between the ones that are sick and dying or the amimals that may or may not be infected.  However,it appears that that choice was made at a great cost and now the entire heard appears to be on the downhill path.  Studying a considerable amount of the research, it appears that little progress has been made since 1998, and the best our government researchers could come up with in 2009 or early 2010, was to isolate the wild from the domesticated, (Really?) and or kill off the Big Horn heard to a more managable level.  Still don't understand why government research inevitavbly thinks that is always a good solution.  But, then, who am I to ask, I only pay their salaries, right?

CVC's picture

I read your post and then

I read your post and then reread it and thought about it some.  At first, 44 didn't seem like a lot, but I realized what percentage of the herd it was and it is incredible that they would kill that many on just a whim.  What has changed that the domestic sheep herd is causing them to get sick.

I am just assuming that the wild sheep and domestic sheep have always been in close proximity to one another so why is it now becoming an issue?  We really should be on top of this and not like Labador that losing 90% of its herd and doesn't realize it.

Ca_Vermonster's picture

I have actually been able to

I have actually been able to see a few of these animals in person and they are indeed beautiful creatures.  I don't know if i would shoot one, especially if they are truly this much in danger. Hard to believe that in todays time, we can be so successful in bringing back the ones we almost wiped out, like elk and buffalo, and deer are exploding across the county, but we cannot seem to explain the decline in some species like this.  And the funny thing is, these creatures already live well away from humans, so it's not like we are encroaching on their land and destroying their habitat. 

Puzzling indeed.

gatorfan's picture

Pretty amazing animals

Pretty amazing animals indeed!  Honestly, they have never been on my list of "wish I could hunt..." but I would love to be able to see some in person.  I really enjoy watching shows that are about these elusive and majestic creatures.

Hawkeye, it sounds like the research you are involved with really brings this to heart!  I am even more interested in this research now that I sort of feel a connection to someone that is actually conducting the research.  I am sure, with the emphasis that is being put towards the situation, it is only a matter of time before you guys find the answers and eventually, the solution.

Good luck to all of you that are trying to save the beautiful animals!


hawkeye270's picture

They really are the king of

They really are the king of the mountain. There is just something that you can't really put into words when you see a big, 12 years old full-curl ram standing on the edge of a cliff overlooking his domain. He owns the place and he knows it. They live in incredable country that can give you your best memory one monent and then take your life the next. They are my favorite species clade but if you made me pick my favorite species, I would be hard pressed to give up an answer. Either the Rocky Mountain Bighorn or the Dall's Sheep. I really hope that we can come up with an answer to these wonderful species' decline in the near future so that my grandchildren can witness their splender.

CVC's picture

When I was in BC we had to go

When I was in BC we had to go into town to meet with the game inspector who had to check our skulls and paperwork then issue us an export certificate.  While we were there we got to see bighorn sheep right in town lounging in people's yards and grazing on the grass.  It was really cool to see.  No big rams, but lots of young ones, ewes and kids a plenty.

How would you like to wake up to that sight everyday?

CVC's picture

I don't know why Bighorn

I don't know why Bighorn sheep carry such a mystic.  I mean they're just sheep right?  Nah, not hardly, there is something special about them and I support research to find out ways to protect them.  Interesting how a lot of discussions about domestic herds adversely affecting the wild ones, elk for example.  Not sure what the answer is, but as the article says they are iconic and like the American Bald Eagle we need to make sure they are protected.

hawkeye270's picture

This is a very disturbing

This is a very disturbing trend and one that all the wildlife agencies are trying to figure out. The biggest cause of the die offs is pneumonia like the article mentions. It states that it is caused by a bacteria. The symptoms that end up killing the sheep are not from physical damage the bacteria does per say, it is caused by toxins that the bacteria secretes called leukotoxins. I have had the honor of working with some very intelligent figures working to address bighorn declines but there just aren't any clear cut answers, like in most wildlife diseases. We haven't been able to get vaccinations to save herds, we haven't been able to get cull and transplant programs to fix the problems. Another thing that the article does not mention is the fact that the key to this problem is not adult bighorns dropping dead. Although we have seen some fairly large die offs of adult individuals. The root of the problem lies in lamb recruitment. Once pneumonia starts hammering a herd, the lamb recruitment nose dives. We don't see a problem in lamb production... its getting those lambs to a year of age that just does not happen in affected herds. You see nearly every ewe in the population drop a lamb and within a few weeks... they are all dead. That is what is so hard about doing field work on them. You get so excited and then they start dropping like flies.