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Thread: Article: sheep horn size and trophy hunting

  1. #1

    Default Article: sheep horn size and trophy hunting

    I'm not sure if this has been discussed before but I thought it was interesting.


    Nature 426, 595 (11 December 2003) | doi:10.1038/426595a
    Sheep horns downsized by hunters' taste for trophies

    John Whitfield, London
    The horns of some bighorn sheep are getting smaller, because hunters are picking off the most impressive rams before they reach their breeding peak.
    A study of one sheep population in Canada shows that hunting can harm the gene pool of a species over just a few years. That means there should be tougher restrictions on what animals can be taken, says David Coltman of the University of Sheffield, UK. "For selection to be having this effect is of fundamental importance," he says.
    Biologists have long suspected that hunting can affect animal evolution. Elephant poaching, for example, is thought to have led to an increase in the number of tuskless animals in Africa. And in Canada, the hunting of moose seems to have resulted in animals with smaller antlers.
    To pin the relationship down, Coltman and his colleagues studied the sheep of Ram Mountain, Alberta. This Canadian province is home to the world's biggest bighorn sheep, and is a magnet to hunters. Since 1975, 57 of Ram Mountain's rams have been shot about 10% of all males in the population each year from 1975 to 1996. In 1996, the government restricted hunting to males with a large, 'full curl' of horns, which has reduced the cull to zero in recent years. Coltman looked at rams from 1971 to 2002, and found that horn size fell by about a quarter over this period (see page 655). Despite the recent drop-off in hunting, horn size has not recovered.
    Large horns are generally correlated with large, healthy rams, says Coltman, so the effect on the population's genetics is probably deeper than the effect on horns alone. He suspects that hunting is also influencing mating behaviour, with fewer rams butting heads to fight for partners.
    One reason for the change is that hunters prefer rams with large horns, as they make for more impressive trophies. But it could also be an accidental side effect of some hunting regulations. Restricting hunting to males with large horns is meant to limit the killing of animals that are not old enough to breed, but it also encourages the culling of animals that grow large horns early in life. "You force every hunter to harvest the very animal that you're trying to grow," says Kevin Hurley, a wildlife biologist with the Wyoming Fish and Game Department and executive director of the Northern Wild Sheep and Goat Council.
    A better strategy may be to limit the number of hunting permits, argue both Hurley and Coltman. In the western United States, it is common to offer a limited number of permits for bighorn sheep by lottery or auction the right to shoot a single ram frequently fetches as much as $100,000.
    Hunters are generally sympathetic to the need for management, says Kelly Semple, executive director of Hunting for Tomorrow, a coalition of hunting groups based in Edmonton, Alberta, as hunters do not want to drive large-horned animals into extinction. But she warns against generalizing Coltman's results to all species and locations.

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    Default Oh boy

    this should bring out some wonderful discussions

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    Member aksheephuntress's Avatar
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    Default Oh Boy,too

    ...Yeah I agree....the mud (or,snow) ...and sarcasm might commence slinging, soon. I am really new to this forum...but I had no idea sheep hunters were so opinionated and cut-throat with one another....guess I've been sheltered,here,on the Kenai.(though...thank you, Alderwillow, for the post...and this is not directed toward you-or to you either,Cutter..)...hopefully the majority of us sheephunters will probably be united on the opposition of this one.....
    ...I'm not staying around to find out...
    ...Think sheep-countdown to August...

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    Forum Admin Brian M's Avatar
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    Quote Originally Posted by aksheephuntress View Post
    ...Think sheep-countdown to August...
    October for me, due to a drawing permit. I may try a general season area in August, but I'm thinking that I may turn my attention towards other species in August, let my walk-in area face less pressure, and just focus on practicing my archery and stalking skills in anticipation of that one October weekend.

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    Member kahahawai's Avatar
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    Sheep season will be here before you know it... fishing really makes the time go by quick...August sheep hunt for me, and October goat on the Isle.... and who knows what else.

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    Moderator LuJon's Avatar
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    August moose for sure. I hope that the spring draw is as kind as the winter draw was. I am putting both the wife and myself in several mat-su cow draws. A near sure thing sure would take the strees out of filling the freezer and let me concentrate on my september Chugach sheep hunt! I doubt that this thread will get too bad we have all rehashed the full curl sheep harvest issue TO DEATH since September. An article with no scientific documentation is not worth much. I think we all pretty much agree that what we need is funding for ADF&G to do thorough population studies. Heimer did lamb recruitment studies years ago and has good data on that justifying full curl regulation but most of (if not all) would like to see new more thorough widespread studies specific to population and yield. Predation studies would also be very benificial I believe.
    Good luck on your hunts!

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    Personally I'm all for horn restriction and permit arias, as are most hard core sheep hunters. Having these restrictions only makes for higher quality game to be taken. Take Friday creek for example, an easy access hunt that anybody with an ATV can get to. Most sheep in this spot are never given the chance to grow to there full potential, there harvested as soon as they hit the full curl mark. Seeing as how this aria went to permit this year, its really going to make for some extremely large sheep and the population to go way up in the next 4-5 years. So anyone that is lucky enough to draw a sheep tag here or any were for that matter is more likely for a chance at a real trophy class animal

    For any one including myself who has never drawn a sheep tag, OUR TIME IS COMMING.......i hope .

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    Forum Admin Brian M's Avatar
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    Quote Originally Posted by huntsheepinak View Post
    Personally I'm all for horn restriction and permit arias, as are most hard core sheep hunters.
    I think you might be surprised at how many hard core sheep hunters are firmly against more permit areas.

    Hard to be a hard core sheep hunter when you can't go hunting year after year because you didn't draw a tag.

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    Member AK NIMROD's Avatar
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    Default reason for full curl restriction

    here is an old article i saved years ago about reason for full curl restriction

    To All:
    I'm the biologist responsible for the full curl regulation in Alaska. Here's a brief history of how it happened:
    When I started studying Dall sheep in 1971, Alaska had the 3/4 curl rule. We'd inherited it from Wyoming via Washington DC during territorial days. The 3/4 curl might make some sense for bighorns in Wyoming, but the regulation was equivalent to "bucks only" or "cocks only" harvest rules which really had no biological justification. They were just more conservative than open seasons when populations were scarce.
    My early field work in Alaska consisted of studying a bunch of collared ewes I'd "inherited" from an unusually far-sighted biologist named Jim Erickson. Jim was killed on a sheep survey in the Brooks Range in 1970. He and my original partner had trapped and collared about 200 ewes in the Alaska Range south of Fairbanks. That's where I got my start. As part of our work, we kept track of these ewes and how they did reproductively. What we found was that they often had lambs early (delivering at 2 years of age), but seldom had lambs two years in a row.
    That population was a high density one, and subjected to an intense 3/4 curl harvest. Initially, managers thought the poor reproduction was due to crowding and insufficient food to go around. However, during our work (which included lots of winter backpacking to determine home winter ranges in the study area---radiocollars had not been invented yet) we noticed that the ewes weren't weaning lambs in October as they should have. They were carrying them on milk all the way through to April. Usually extended nursing periods are signs of good range...ewes don't nurse lambs very long on poor quality food. Also, the fact that many yearlings were being bred suggested food wasn't limiting. Usually early breeding is a sign of good, not poor range.
    So, what were we to do? The data didn't suggest a nutritional problem, but the population was at high density. Eventually, I prevailed on the managers to let me do a comparative nutritional study on a population which was in about the same conditions weather wise but was 150 miles east of the study area. This area is now called the Tok Management Area, and has been managed for trophies since 1974...about the time I went there to work.
    When we looked at ewes there (where populations were not dense, and horn growth was fantastic) we found they virtually never bred till the age of three years, and then had a baby every spring. They also ended nursing "on schedule" in October.
    Before we got into a wholesale slaughter of ewes in the original study area, we compared the nutrition available to each group. There was no difference!
    This meant that the most likely explanation of why one population was outreproducing the other had to do with something other than food. The obvious difference between the groups was the number and age structure of rams. The good group had many more rams, and way more old rams...because it was managed for trophy hunting by the state's first full curl rule...which came along in 1974.
    Through a series of biopolitical events which are too complex to discuss in this biological story, we eventually changed the regulations in the poor area to 7/8 of a curl. That fixed the "early breeding" and "alternate year" reproduction problem, but the harvest of 7/8 curl rams didn't increase any over what it had been at 3/4 curl.
    Eventually we figured out that the reason we had more lambs but not more rams to shoot was that the survival of the lambs to 7/8 curl size was poor. As it turned out, the young rams were becoming active as social dominants (and breeders) before they should have because old rams (full curls) keep the youngsters in their place till they are physically and socially ready to breed. Once any ram starts breeding, his life expectancy is short. The stress of breeding kills them in only a few years. If they start at about 8 years (normal full curl age--except in the Brooks Range where it takes 10 years on average) the oldest survivors will be about 12 when they die. If they start at 2.5 years of age, they will die at about the age when they would normall be reaching 7/8 of a curl.
    All this took about 20 years. The first full curl reg was in the Tok Management Area in 1974. Then a couple of units went full curl as an experiment about 1984. We went statewide (except for the Brooks Range--again for political not biological reasons) in 1989, and finally statewide in 1993 or so...if my memory serves me correctly. If you want specifics, email me at .
    When we went to full curl, we noticed that given the same ewe base (population size) our harvests soon went up by about 35 percent. Subsequently, as others in this forum have pointed out, bad weather and high predation depleted the populations to where we are in a real mess now. Unless fish and game (I retired three years ago). I now serve as a Director of the Foundation for North American Wild Sheep. Thanks to Paula Karres from Foundation Headquarters in Cody WY for turning me on to this forum.
    If you want to know more about management of wild sheep in North America, I suggest you contact Kevin Hurley of the Northern Wild Sheep and Goat Council.... Kevin is executive director of the Northern Wild Sheep and Goat Council, and can put you onto the latest and most complete book on sheep management in North America. It came our of a conference we had in Reno during April of 1999. The whole story about Alaska's full curl regs is there, along with much, much more.
    Thanks for reading. Keep thinking and asking those questions. Regards to all. Wayne

    RETIRED U.S.A.F. CAPT.; LIFETIME MEMBER NRA; LIFETIME MEMBER ALASKA BOWHUNTER ASSOC.
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  10. #10

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    Quote Originally Posted by LuJon View Post
    August moose for sure. I hope that the spring draw is as kind as the winter draw was. I am putting both the wife and myself in several mat-su cow draws. A near sure thing sure would take the strees out of filling the freezer and let me concentrate on my september Chugach sheep hunt! I doubt that this thread will get too bad we have all rehashed the full curl sheep harvest issue TO DEATH since September. An article with no scientific documentation is not worth much. I think we all pretty much agree that what we need is funding for ADF&G to do thorough population studies. Heimer did lamb recruitment studies years ago and has good data on that justifying full curl regulation but most of (if not all) would like to see new more thorough widespread studies specific to population and yield. Predation studies would also be very benificial I believe.
    Good luck on your hunts!
    "An article with no scientific documentation is not worth much."

    Actually, its a review article of a study that has surely been published elsewhere. We can track it down (and probably should) but I doubt Nature summarized it incorrectly or referred to it if it wasn't a real study...and as the study had not been referred to before, it was worth presenting, in multiple ways, for the sake of the information it brings. It may present some data that runs contrary to the hopes of most on this forum, but it can't be ignored, and we could have to deal with it some day if the BOG ever used it to justify a decision.

  11. #11
    Member kahahawai's Avatar
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    Default Interesting Article

    AK Nimrod, that's a good article on fullcurl restrictions.

    I did notice that north of Atigun pass along the Hwy where I seen a dense population of Ewes, and what looked to me were mature Ewes that they did not have lambs, in fact only a few of them may have had lambs. I am not a biologist, nor am I an expert in Sheep, and I wouldn't just suspect that predators are the cause right off the bat either, but maybe there is a low production rate, I did see alot of rams, and few legal ones, but one would think in a weapons restricted hunting area, that borders a national park you would think this area would be flourishing with fullcurl rams, don't think thats the case.

    More hunters period! I believe that Sheep hunting is a GROWING addiction without a doubt! More hunters are taking to the mountains, back when I was stationed here in the in the mid-eighties, not alot of hunters talked sheep hunting, It was moose and bears! from what I saw. To harvest a legal ram, stereotypes a sense of accomplishment, and once you take that first ram and set the bar, you keep coming back for more and bigger and better. I myself have not taken a sheep, and when I go to a friends house or Sportsmans W.H. and see those beautiful trophies, I will admit I have the feeling of Envy! I am not part of an elite group ( those who harvested a ram) . However, Even if I don't harvest a sheep this year, I do have the experience and the enjoyment of taking to the mountains, sheep huntin' is challenging and down right fun, period!!!.

    I'm no expert, but I'm sure there are still some record book rams that still lurk these mountains in drainages that human foot has never stepped upon.

  12. #12
    Forum Admin Brian M's Avatar
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    Quote Originally Posted by kahahawai View Post
    More hunters period! I believe that Sheep hunting is a GROWING addiction without a doubt! More hunters are taking to the mountains,
    That's not what F&G stats show. Someone recently posted the numbers (I don't have them at hand - but will look up later), and the numbers of sheep hunters is down, not up. Success rates have remained about the same, even though the total # of sheep killed per year is down. The rates have remained stagnant, though, because fewer people are pursuing sheep.

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    Member kahahawai's Avatar
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    Brian, wouldn't you think more hunters are taking to the mountains these days because of the easier opportunities to access the back country? Its more attainable now to acquire an airplane ( seems like everyone has one in AK) Jet Boat, ATV, Argo's , mokai's , rafts and etc. and etc. then back in the day when Jack Wilson was flying hunters in and out. Of course this is my speculation....Don't really have to be in sheep shape anymore either, we've seen that through the videos...(IMO)

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    Member AK NIMROD's Avatar
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    Kahahawai- brooks range along haul road is open for fed. subsistance hunting and local residents can shoot 3/4 curl ram with rifle along road in archery only area, if i remember correctly ....have not looked at those fed regs for a few years. also to east is open for 3 sheep in the winter.
    RETIRED U.S.A.F. CAPT.; LIFETIME MEMBER NRA; LIFETIME MEMBER ALASKA BOWHUNTER ASSOC.
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    Member ak_powder_monkey's Avatar
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    That must be bunk because evolution didn't happen and never will right guys
    I choose to fly fish, not because its easy, but because its hard.

  16. #16

    Default Evolution

    "That must be bunk because evolution didn't happen and never will right guys."

    There's a big difference in animals adapting and evolving. Horns can get smaller, but they can't turn into wings!!! Macro vs. Micro evolution.
    "Everything that lives and moves will be food for you. Just as I gave you the green plants, I now give you everything."

  17. #17
    Forum Admin Brian M's Avatar
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    If you guys would like to debate evolution, the general discussion forum is the place for it. Thanks.

  18. #18

    Default Sorry

    My bad Brian, just couldn't let that one go. It is interesting at the end of the "article" that "But she warns against generalizing Coltman's results to all species and locations". This is exactly what I thought because I just read an article in Fair Chase about how the rams in Montana are getting bigger. I am always suspect of an alterior motive.
    "Everything that lives and moves will be food for you. Just as I gave you the green plants, I now give you everything."

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