Wyoming Game and Fish says wolves hurting cow:calf ratios in certain areas

Wyoming Game and Fish has released a story claiming for the first time that they have data showing wolves are hurting elk cow:calf ratio.

Story in the Jackson Hole News and Guide.

Here is a link to the WY Game and Fish web site where you can find a link about the study. Unfortunately, it is a Word file, rather than an HTML or pdf file.

At any rate, the claim is that cow:calf ratios are down in 4 of the 8 elk herd areas occupied by wolves. There are 21 herd areas in total in Wyoming.

Update: OK the correct link the the report has been forwarded. Read it at: http://gf.state.wy.us/downloads/pdf/FinalElkCCRatios3-23-07.pdf.

There has been a general negative trend in cow/calf ratios throughout Wyoming since 1980, both in areas without wolves and with wolves.  Of the eight herd units where wolves are present, 4 showed statistically significant changes in the slope of the regression line since wolves were reintroduced. In order of magnitude of change, most changed was the slope for the Cody herd (most change downward), then Gooseberry, Clarks Fork, and Green River. The four herds that did not show statistically significant changes in slope, post wolf, were Jackson, Fall Creek, Wiggins Fork and Piney herd (just southwest of Green River).

Three of the four herds with statistically significant changes are east and/or southeast of Yellowstone Park (one is south–Green River).

Clark’s Fork, and Jackson are the 2 herds that have had wolves for the longest period. In terms of numbers of wolves, the study did not have the data to calculate firm correlations (due to changes in packs size and location). However, it is clear to me that the area east of the Park has had a substantial and an increasing number of wolf packs, more so than other parts of Wyoming.

The study did not rule out competing hypothesis for the decline in cow/calf ratios, but I think the study lends support to the hypothesis that wolves are responsible for some of the decrease in elk recruitment.

I have to wonder why the Jackson herd did not show a statistically significant downward change in regression slope because it has had wolves packs for a long time, and the packs have been large.

There might be important other factors east of Yellowstone Park that affect cow/calf ratios of which I am not aware. If anyone is aware, please comment. Since the Dept. study performed analysis of variance, I wonder if there were any significant interaction terms?



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  1. Jim Avatar

    I couldn’t get the link to work either.

    New Report Examines the Effects of Wolves on Elk

    CHEYENNE, March 23—A new report released today by the Wyoming Game and Fish Department takes a detailed look at the effects that wolves are having on elk populations in northwestern Wyoming. In the report, department biologists analyzed statewide elk population data from 1980 through 2005.

    Wolf reintroduction began in 1995, when the federal government released 14 wolves in Yellowstone National Park. Wolf populations reached recovery goals established by the US Fish and Wildlife Service in 2002 and continue to grow. At the end of 2006, there were an estimated 36 packs in Wyoming, including 311 individual wolves.

    To determine the impacts wolves are having on elk, biologists looked at trends in calf:cow ratios over a 26-year period, both in areas where wolf populations have been established and in areas where wolves are not present. Of the 21 elk herds included in the analysis, eight are currently occupied by wolves.

    “We have seen a downward trend in many of Wyoming’s elk herds over this 26-year period,” said Wyoming Game and Fish Department Wildlife Chief Jay Lawson. “That trend is likely due to long-term drought and other habitat related factors. But in half of the herds occupied by wolves, we saw a significantly greater rate of decline after wolves were established compared to herds without wolves. We can’t attribute that increased rate of decline to any factor other than wolves.”

    Biologists feel an elk herd’s population can be maintained at objective and provide some hunter harvest when the ratio of calves to cows is around 25 to 100. Once ratios fall below 20:100 there is very little opportunity for hunting. Four elk herds in Wyoming with wolves present have dropped below 25 calves per 100 cows, and two of those herds are below 20 calves per 100 cows. All four herds had declining ratios before wolves were present, but the rate of decline increased significantly after wolves were established. Currently, the only elk herds in the state with recruitment rates that will not support hunting, or possibly even stable populations, are those with significant wolf predation.

    “There are a lot of different factors affecting wildlife throughout the state, and wolves are a relatively recent addition to the challenges facing our elk,” said Lawson. We’re very concerned about the effects of wolves on the state’s elk and reduced hunting opportunities for the public. This report helps us understand how wolves are contributing to changes in our elk herds. We also hope this data will provide us tools to work with federal agencies in charge of wolf management to minimize the effects of wolves on elk and elk hunting opportunities.”

  2. david aiken Avatar
    david aiken

    The article mentions the affected areas are north of Pinedale. I suppose it is just a coincidence that this area also has alot of gas wells and exploration. Wouldn’t it be interesting to lay the map out of the 4 herds with declining numbers and see how much development and mineral exploration has been done in those areas over the last ten years.

  3. Moose Avatar

    Additional studies that include the info below are needed before any conclusions can be made. I wouldn’t be suprised if wolves have impacted calf recruitment in some units. I would be interested to know how these rates vary as elk learn avoidance behavior in the initial years of wolf exposure- in many “wolf” units recruitment rates appear to increase again after the initial exposure years.

    Again, this just points out how much it is in Wyoming’s interest to get its act together and come up with a reasonable mngmt plan.

    From the study:
    “Additional information such as year-round precipitation to index habitat conditions, relative wolf to elk densities, elk body condition, and reproductive rates would be useful to definitively evaluate the influence of wolf predation on elk recruitment.”

  4. elkhunter Avatar

    Even when they publish a report stating that wolves have had a negative effect, you guys always undermine what they said and try to bring up other reasons as to why the calf recruitment is down, but of course I am sure the report is not valid in your minds.

  5. Joe S. Avatar

    Natural predators will kill at every opportunity, unless they are so satiated they cannot drag their fat guts across the ground.

    When a resident predator population wipes out their resident food source(and they will, it’s a proven fact of nature), they will: 1)migrate to find new prey. 2)kill and eat other resident predators(including each other). 3)starve and die.

    This cycle is natural, it’s as old as time, and you learn the basics of it in your first semester of Wildlife Mgmt. Usually they use the lynx/hare cycle as the example.

    Ive lived and hunted long enough to see it with my own eyes. The most glaring example in my personal experience is Mulchatna herd caribou, where a booming predator population made up of Man/Wolf/Bears wiped out the herd in about a 6 year period. Now I’m willing to acknowledge that disease was the catalyst for the boom/bust cycle, but the predators benefited immensely and I went from seeing a wolf or two a season to up to 30 wolves a season.

    I don’t get too bent out of shape about it since I can shoot wolves in AK and I do at every opprtunity(the tag is only $30). Competition among predators is the law of nature.

    What ticks me off, is that in the lower 48, wolves get a free pass, and so do CA Mtn Lions(who now include joggers and Mtn Bikers on their menu) and we are not allowed to compete or kill with these predators.

    Prey populations have been forced by human activity into islands of habitat. When an effective predator like wolves is introduced into these fragmented ecosystems and are allowed to go unchecked, they will wipe out concentrated populations of game and move on…and current state and federal regulations allow this. The result is that human hunting opportunity is limited or worse yet eliminated.

    (On a side note, this is largely due to urban/metro wildlife lovers, who BTW don’t hunt, pressuring state and federal agencies to sacrifice their fellow man’s opportunity to hunt..so that on the off chance, they might hear a wolf howl in the wild on their ONE family camping trip in the summer)

    And although predators may not be impacting hunting opportunity for whitetails in Wisconsin. Wolves and Mtn Lions WITH SPECIAL PROTECTED STATUS are having a serious impact on elk/deer/moose/sheep populations in the Rocky Mtn States, CA, and AK.

    I love seeing wolves, I love hearing wolves howl in the wild…I also love hunting wolves and especially SHOOTING THEM. I think the wolf is one of the greatest trophies a hunter can ever take.

    But this debate, lower 48 wolves and mtn lions with special protected status, is especially frustrating for me when I think about the millions of dollars spent by State agencies and private citizens working through conservation groups such as RMEF, FNAWS, and SCI to improve habitat for wildlife in an effort to increase sustainable yield #’s. All of that hard work and money is all for naught when a Federal or State agency turns to the hunters of America and says, “Wolves/Lions are natural…you’re not. They can hunt..you can’t. But I think Safeway is open 24 hours now!”

    But I digress…

    Sorry for the long post, I hope I contributed something to this debate… You guys have a great day!

    PS-Please have a wolf tag in your pocket if you hunt AK and give serious thought to investing in a MTN Lion hunt in a state that offers hunts for them, thank you!

  6. Buffaloed Avatar

    I talked to a biologist in Idaho today and asked him flat out…. “Would you agree with the statement that weather plays a bigger role in elk populations than predation?” He answered “Yes.”

    He also pointed out that fire plays a big role in where the elk tend to move because fires tend to improve habitat after a couple of years. He also said that some of the places with the highest cow:calf ratios also have some of the most dense wolf populations. He also mentioned that rains in the summer and fall tend to effect the size of calves born in the spring. I had never heard many of these things and it goes to show that it is not a black and white issue as elkhunter would like it to be. All of these things play a role in predation and survival. Bears, wolves, and mountain lions have different impacts as well.

    I disagree that predators will kill at every opportunity. I have seen elk investigate denning areas many times and they were not even bothered by the wolves. It’s a ridiculous notion. I’d like to see many of you try to make a living by killing your meal with your teeth. Words like “proven fact” and “every” don’t belong in disscussions like this.

  7. Ralph Maughan Avatar

    It’s obvious that once the correct URL to study was found, most of the folks who posted didn’t read it.

  8. Jay Avatar


    I don’t know what school you went to, but it appears they didn’t explain to you very well the nature of the 11-year cyclical nature of the hare and lynx. Read some literature on the cycle and you’ll find that most biologists consider that particular phenomenon a bottom-up driven process, meaning habitat is the driving force in the growth, and decline, of the hare. At the beginning of the cycle, hares are at low densities, and thus have lots of food available. Likewise, lynx densities are low. The hare population increases with the abundance of food, which also allows for the lynx to increase in numbers. Hare densities increase to the point they outstrip their food supply and the population crashes (it has nothing to do with predation–lynx can’t come close to keeping up with the boom in the hare population–studies measuring food availability show that the hares have stripped their food source up to where they can no longer reach fresh browse). Lynx populations will stay high for a couple years after, but they eventually disperse, starve, and reproductive rates drop due to the lack of food (they don’t go around eating all the other like you claim) bringing the population back down to early-cycle levels. The habitat recovers with so few hares around, and the cycle begins anew.
    So there you have it…if you’re going to use natural predator-prey systems to illustrate your examples, at least have the decency to understand them, rather than twist them to fit your limited view of predator ecology.

  9. elkhunter Avatar

    I know you are a wolf lover, but do you honestly think, that in no way shape or form that predators do not have negative effects on big-game? Whether that is population, calf recruitment, over-all health of a population, and I am not just talking about your precious Wolf. I mean all predators. Go and read on the ID Fish and Game website this years report of Elk Ecology and the study they did with bears and mountain lions and the effect they had on calf recruitment. And that if they have those types of numbers every year, then they would not even be able to sustain a hunting season. Read it, but I am sure you will discount it in some scientific way, and make it out to be that the predators are the one’s at risk.

  10. Joe S. Avatar

    Here you go Jay (out of decency)

    The Lynx-Snowshoe Hare Cycle

    The primary food of the lynx is the snowshoe hare and therefore the population cycles of these two species are closely linked. When hares are plentiful, lynx eat little else, taking about two hares every three days. When hares are scarce, lynx also prey upon mice, voles, squirrels, grouse, and ptarmigan, and they will also eat carrion. However, these food sources often do not meet the lynx’s nutritional needs. Some lynx cannot maintain their body fat reserves, and become more vulnerable to starvation or predation. Other lynx manage to remain healthy by using alternative prey and food sources when the hares are low. When snowshoe hares are scarce, many lynx leave their home range in search of food.

    and this is what i said:
    When a resident predator population wipes out their resident food source(and they will, it’s a proven fact of nature), they will: 1)migrate to find new prey. 2)kill and eat other resident predators(including each other). 3)starve and die.

    Not sure i see the twists your referring to…but im sure you’ll be kind enough to point them out…

  11. Jay Avatar

    Elkhunter–I’m not a “wolflover”, I’m a wildlife lover: bears, wolves, deer and elk, wolves, lions…I appreciate them all. I don’t single out specific species to like because I can shoot them and put their head on my wall. I brought up the lynx-hare cycle because Joe used it as a generalization for all predator-prey sytems, which is bogus. Absolutely there are differences between lynx-hare and wolf/bear/lion-ungulate: reproductive rates (both predator and prey) survival rates (again, pred. and prey) alternative prey, etc., etc., etc. make the two very different in terms of population response.
    Joe, what you said was the predator wipes out the prey population and use the lynx-hare as an example–completely off base, because it’s the prey that wipes itself out by eating themselves out of house and home. And contrary to what you say, wolves, bears, lions, and coyotes are not going around eating the other (and each other)–all those predators are co-existing fairly peacefully in Yellowstone, Alberta, BC, etc.–show me a scientific article documenting such intra- and interspecific predation and I’ll reconsider my stance.

  12. renae Avatar

    David: The elk herds around pinedale[Jackson and Piney] were unaffected it says. The places they mentioned that were are up by yellowstone.Buffaloed; In Wyoming the wolves have effected the elk herds the worst.Wolves might not kill at every opportunity but they have been seen killing elk after elk on feedgrounds and not eating them.

    No they haven’t. This was an “urban” legend of about 5 years ago (up the Gros Ventre River) that has been completely discredited and discussed in this blog and on my old web site.

    A pack was also eliminated for killing 16 yearling calves that they had not eaten.

    Can you name the pack of give some details? Webmaster

    In Montana some guys on horseback discovered 3 huge rams killed and not eaten. IF the wolf population stays the same or grows even more which it will our elk are in serious jeopardy!!

  13. Denise Johnson Avatar
    Denise Johnson

    In reviewing the charts on the link. It appears that an overall decline in elk herds was present post reintroduction. And the decline continued in areas where wolf packs were not present. I concur with your accessment, and question the Jackson herd accessment too. Noted the improvement in Hoback too…
    What really struck me was the decline in the Bighorns, Laramie areas. No wolfs, no bears, lions? That’s their words not mine.
    Seems to me there is another player here…could it be David’s suggestion???
    Interesting that the delisting of the grizz is on the heals of the wolf and Yellowstone Science just released their study on the grizz.
    It shows me how all spiecies are inter-related…preditor/prey etc.
    Great articles and food for thought!
    You just gotta LOVE this BLOG!

  14. Ralph Maughan Avatar

    While I think that the statistics show wolves are likely responsible for some of the additional decline in 4 of the herd areas, no news media have noted the more important finding — that the trend is mostly downward in all of the state due to “habitat and drought” (according to the the G & F department).

    The trend is not downward in neighboring Idaho. Idaho’s elk population seems to be stable, including the hunting units with wolves.

  15. renae Avatar

    Webmaster: The wolf pack I was refering to in both cases was the prospect pack.

  16. Sally Roberts Avatar
    Sally Roberts

    How about the fact that this article is not peer-reviewed? Wyoming Game and Fish just publishes this? And who reviewed it? I believe that wolves have contributed to the declining cow/calf ratio in some way….since they do eat elk. However, the report does indeed show that some herds were on the decline pre-wolf. Funny that in our media you can publish something and people take it for fact. I would be more inclined to take note of this data if it were peer-reviewed.

  17. Ralph Maughan Avatar

    With Dale Hall in there as head of the U.S. Fish and Wildlife Service, the former Speaker of the Wyoming House as his number two, Dirk Kempthorne, former governor of Idaho who actually seemed frightened of big animals, as Secretary of Interior, they aren’t going to be asking for any peer-reviewed data. These guys hate scientists, especially because they keep coming up with the “wrong numbers.”

    They are just more of the Bush Administration’s attack on science in favor of fairy tales — that Administration that believes wishing makes it true whether it is war, politics, or science.

  18. Dave Avatar

    Weather (including both rain and snow) play a significant part in the elk harvest and herd health in Wyoming-this is true but I wish to bring up anither point.
    I live near Cody and frequently shed antler hunt in areas occupied by wolf packs. The largest single difference I have observed is a drastic increase in the number of mature elk killed by wolves. Among a group of several fellow shed hunters in spring 2006 we found 12 dead bulls-all mature, most were 6 points. We can talk about cow to calf ratio but also must consider the effects on the herd when healthy elk in their prime are taken down. Wolves are quite simply destroying the most viable parts of the herd.

  19. Mike Avatar

    I am 52 years old. I have been living and working in the mountains in and around yellowstone park since 1972. There is absolutely no dobut that wolves consume very little of the elk they kill. Many times a grizzly bear will run woles off a kill. Because prey sepcies are so abundant, wolves are not motivate to consume much more than the entrails, the most nutrisious part. I have watched 3 wolves chase down and kill a cow elk . From a distance it looked like they didn’t eat it so I rode over to the kill site. These 3 wolves had eaten only the milk laden spring udders and moved on. I went back to the kill 3 days in a row with no sign of wolf activity . The fourth morning sign showed a grizzly with at least one cub had dragged off the carcass after consuming part of the intestine on-site. We have had a series of very mild winters since 2000 which should be pushing elk recruitment up not down.

    In June of 2007 in one weekend I found 3 separate herds of cow elk. The average adults per herd was 72 the average number of calves was 3. One herd had 1 calf. Another had 2. One herd had none. Either something has drastically affected fertilization rates or something is killing calf elk almost as fast as they hit the ground.

    Bull/Cow ratios remain stable No significant findings of brucellosis has been found to substantiate a theory of fertilization rates or spontaneaous fetal abortion. The weather has been dry but stable and mild for 8 years.

    Meanwhile the “scientific” community so many seem to review. wants more data, more study, more time. They want peer review” which is just another way of saying we want a committe of our guys to look at it and edit the research to support OUR position.

    They sit in far away places and read the blogs of pro predator politcos having never gone and actually SEEN what is going on. Well I have and so have thousands of Wyoming folk.

    Bury your head in the sand if you like. The coming court battle over delisting will last long enough that severtal of Wyoming’s local elk herds will be irrevocably destroyed.

    Then we’ll have the same batch of idiots crying out for elk to be put on the endangered species list.

    We talk about wolves as if they are a problem unto them selves. In fact a portion of th elon term decline of Wyoming elk populations are also partly attributed to the steady increase in grizzly bears, mountain lions and coyotes. All of these prey on young ungulates.


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Ralph Maughan