Study: Wolf’s coat color affects reproductive success

Wolf pups thrive when born to a big wolf pack and have a large mother-

A new study out by well known wolf researchers have found that in Yellowstone Park at least black wolves don’t have the reproductive success that gray wolves do.  It appears that the gene for a black coat, which entered the wolf gene pool thousands of years ago, does more than affect coat color.  Black wolf  females do not have the reproductive success that gray females have.  On the other hand, black wolf pups go on to grow up and thrive more than gray wolves. As a result this may be one reason the Park has about a 50/50 ratio of gray and black wolves.

The black wolf gene became part of the wolf heritage from some ancient black dogs according to a study a few years ago.

-The biggest benefit a pup can have, however, is not coat color, but the pup’s mother’s body weight and the size of the pup’s pack.  A big pack is able to help a large mom, positively interacting with her size.  Pack size and pup success is a non-linear relationship, however, with additional wolves after 8 in a pack adding nothing more to success, with pup success declining in even larger packs.

It is well known the Yellowstone Park packs have a much more favorable structure for wolves than outside, where the packs are smaller, often shot up in hunts and to protect livestock from the minor attacks wolves make on them.

It would be interesting to see if smaller packs cause more “trouble” for humans than larger packs (the total number of wolves being equal).

An article about the study by Drs. Dan Stahler and Doug Smith of the National Park Service’s Yellowstone Wolf Project, Dr. Daniel R. MacNulty at Utah State University, and Drs. Robert Wayne and Bridgett vonHoldt of the University of California, is found in Science Codex. Healthy mom with lots of help key to thriving brood say scientists.

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Update: Dr. Dan Stahler sent me a link to a You Tube video he made on the study.



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  1. Immer Treue Avatar
    Immer Treue

    Healthy moms is a no brainer. Coat color, so many variables. Does black do best in deeply wooded areas? Yellowstone and surrounding areas a bit more open. Black/darker coat on a pup is going to absorb more solar energy, less fuel to burn for warmth when smaller volume to body surface area.

    Hunters: I don’t know, but does that black pelt look more impressive than gray or lighter colors?

    1. Rancher Bob Avatar
      Rancher Bob

      Personal value of pelt color depends on the hunter, but all black pelts sell for a higher price on the open market, followed by near white pelts. Myself I like the black/silver.

      1. Immer Treue Avatar
        Immer Treue

        Rancher Bob,

        Those black wolves are impressive. Been close to two of the three I’ve seen. But the intricacies of the multi-colors present in the typical gray wolf are beautiful.

        The IWC has a young black and silver female. Never seen one in quite that pattern. All said, they all look better in the wild than hanging on a wall.

        1. Rancher Bob Avatar
          Rancher Bob

          Death has that effect on most things one has seen alive.

  2. Jeff Avatar

    I’m not sure they are talking the color per se, versus some underlying genetic component that is only there in black wolves. It is my understanding that the black phase of gray wolves is only present in the North American Sub-species of wolves. That is to say Eurasian wolves are all gray. Are there black wolves in Great Lakes, Eastern Canada and Mexican Wolf Populations?

    1. Maska Avatar

      There are no known black or white wolves in the Mexican gray wolf population.

      “Mexican wolves typically weigh 50 – 80 pounds and measure about 5 ½ feet from nose to tail, and stand 28 to 32 inches at the shoulder. They have a distinctive, richly colored coat of buff, gray, rust, and black, often with distinguishing facial patterns; solid black or white variations do not exist as with other North American gray wolves.”

      1. Immer Treue Avatar
        Immer Treue

        I have seen solid black wolves in Minnesota on three separate occasions.

      2. Jeff Avatar

        That’s interesting that there aren’t white lobos as I thought that was one of the traits of the most famous lobo in New Mexico–maybe that was all fabricated for the story. Do those colors not exist because the 6-8 that were orignial just happened to all be gray or are there none in the historical record?

    2. ma'iingan Avatar

      We are seeing increasing numbers of black wolves in Wisconsin, although they are still uncommon. And we caught and collared our first white wolf about a year ago – it was widely believed that her DNA test would show she was a wolf/dog hybrid but surprisingly it came back 100% wolf.

  3. mikepost Avatar

    I have seen wolves in YP that are so grey as to be considered white to the casual eye and of course certain YP packs have larger percentages of “white” coats. I dont think you can just look at coat color as a stand alone genetic issue. Many times these anomolies are linked to groups of genes that are passed on as a package where that genetic group contains a very beneficial gene and no direct life impacts from the other genes present so there is no further selection to eliminate them. One opposite but illustrative example: in the Boxer dog, white pups (not albinos) also tend to be deaf. Hard to see the direct developmental linkage but the two traits seem to be genetically packaged together.

    1. Ralph Maughan Avatar
      Ralph Maughan


      All wolves turn lighter as they age. They kind of get gray fur like people get gray hair. Really old wolves that were originally gray often turn kind of bluish gray, something you sometimes see in people.

      1. mikepost Avatar

        Ralph, I have a picture of two “white” wolves from the Mollies pack by the lake in YP and they look pretty doggone white to me. I mean like “bone white”.

        1. Ralph Maughan Avatar
          Ralph Maughan


          I didn’t mean to imply that some “gray wolves” are not nearly white.

  4. Rancher Bob Avatar
    Rancher Bob

    As for your question do small packs cause more problems for humans?
    Somewhere I read or was told that packs numbering over 6 are more likely to kill cattle, seems to hold true.

    1. Ralph Maughan Avatar
      Ralph Maughan

      Rancher Bob,

      I don’t know except that for killing elk the optimum size of a hunting party is four wolves.

  5. ramses09 Avatar

    Rancher Bob, why do you come to this web-site?? I’m fairly certain that this is a PRO-WOLF site, meaning the folks who come & comment on it do NOT want to see wolves get hunted, trapped, snared, shot with bow & arrow, etc. I have experienced you folks from Idaho, Wyoming & Montana. There is NO reasoning with the a__holes who LOVE to hunt wolves. They are closed minded & ignorant. They will not read or listen to SOUND SCIENCE.
    So why do you come to this site ….. just to get a rise out of the folks who love wolves & want to protect them from harm.???

    1. Immer Treue Avatar
      Immer Treue


      I’m sure Rancher Bob can speak for himself, but yes, this is a pro-wildlife site and most who post here are pro-wolf, and don’t want the litany of methods included in your list to happen to wolves. That said, RB has his points of view, that at least I don’t look at any more than moderate. And what is wrong with a rancher, who is part of the landscape, engaging in conversation where he can share his world with us? At the same time, perhaps he picks up a few tips on living with wolves, shares what does and doesn’t work in order to move towards a coexistance with wolves rather than the pissing matches that all too often dominate the discussions and headlines.

    2. mikepost Avatar

      While I may not agree with Rancher Bob you sound more “closed minded” than he does…

    3. Rancher Bob Avatar
      Rancher Bob

      Well originally I started visiting here to learn about wolves and wolf lovers. I have no problem with different views it’s what makes this country great.
      Then I began to realize I could offer a different view for those willing to learn. I also learned the world is filled with people like you, those who have all the answers and I could learn from you. That is if someone like me who really LOVE’S to hunt wolves can learn.
      Sound science tells me that the more wolves you have the more they are forced to kill each other, so one question how are you going to protect wolves from each other?
      Second question have you ever experienced folks from Canada?

  6. Ken Cole Avatar

    I’ve seen two “white” wolves (in the same pack) in Idaho but most of the wolves I’ve seen have been gray. I’ve seen maybe 5 black wolves here.

    Ramses09, while this site is a pro wolf website, it is not a place where only those who agree with the editors are allowed to post comments. I get tired of trolls too, but if you want a place just for people who only agree with you on everything then The Wildlife News isn’t that place. It is a place for healthy debate not an echo chamber. Yes, we have blocked several people from commenting here from both sides but I feel that it is better to have to deal with people from a different perspective. It makes our arguments stronger.

    1. IDhiker Avatar

      My wife and I saw four wolves at close range last spring in the Frank Church while backpacking. They were hunting together and I would call them “white.” We’ve seen about thirty wolves in the last five years or so, and with the exception of one other that was brownish, all of the rest have been grey. These four “white” ones definitely stood out from the grey ones. We have never seen a black one.

  7. Louise Kane Avatar

    This coat color issue is interesting but the information from this study about the size of pack and success of packs is extremely valuable and this is best available science is the kind of information that, as it becomes available, needs to be included in the decision making process when determining what effect hunts will have on these animals. common sense tells us these random and aggressive wolf hunts have more impact then the states argue but when peer reviewed science becomes available it should be used. Ralph can you post a link to the study please

    1. Ralph Maughan Avatar
      Ralph Maughan

      Louise Kane,

      This replaces my earlier reply to you. Here is the link in the Journal of Animal Ecology.

      “The adaptive value of morphological, behavioural and life-history traits in reproductive female wolves.”

      It is supposed to be free, but I couldn’t make it work.

      I got my copy from Dan Stahler, yesterday, after I had written the article.

  8. Louise Kane Avatar

    sorry did not see link

  9. Salle Avatar

    The Billings Gazette covered this story (on mother’s body weight) today, with more of Dan Stahler’s awesoma pictures…

    1. Harley Avatar

      Nice pictures!

    2. Larry Thorngren Avatar

      Salle- Dan Stahler gets “awesome pictures” because he has access to government helicopters and airplanes from which he takes his photos.
      None of the photos in the article look like they were taken from over a hundred yards away as park rules require. He did at least put “Yellowstone National Park” on his photos as required by his employer, which he and Doug Smith used to conveniently forget to do when they were selling their photos in calendars.

      1. Salle Avatar

        Actually Larry,

        You sound a little like there’s some jealousy there. Maybe you should apply for a job with NPS or some other agency so you can fly in that two-seater too. (But then you wouldn’t be able to sell your pictures for personal gain!)

        So let me tell you that I know for a fact hat they use a high powered digital zoom for their aerial photos because I helped to buy that system in order for them to maintain that required “safe distance” from the air. I am also well aware of their access to government aircraft, they are federal employees after all and such aircraft is available to them for these observations because it’s part of their job.

        And, they not only provide observations for the wolf project, they (Drs. Smith and Stahler), camera and the aircraft, make use of this equipment and their skills for other wildlife research projects as well. At least they are conducting research with that aircraft instead of chasing down and killing the wildlife for welfare ranchers!

        I am thankful for their work and dedication and champion the unbiased information they provide as public servants. Fortunately for them, they happen to have the best job I can imagine with regard to wildlife, they’ve worked hard to be in those positions and they deserve to be there. I feel they are worth every penny they earn, my opinion but that’s how I see it and I’m happy to send them a pat on the back for the work that they do because they do it well and provide the public with valuable information. And I wonder where you think that calendar cash goes…? If they are sold at the bookstores inside the National Parks, that money goes back into the Park. Even if sold elsewhere, that money goes back to fund their work.

        They’re great pictures, why not just enjoy them instead of being so negative about who took them (because it wasn’t you)?

      2. Ralph Maughan Avatar
        Ralph Maughan

        Larry Thorngren,

        Those photos and videos taken by Park Service personnel using government equipment are available to the public for free use.

        Just ask.

      3. Salle Avatar

        And furthermore Larry,

        Since these Park Employees are the very people who conduct the research and assess management criteria for the wolves, they have the assigned task of also handling these animals, which requires that they be close enough to actually touch them while placing collars and taking biometric measurements. Pictures are part of that set of tasks.

        What’s your issue here?

        Another thing, are you absolutely certain that Drs. Smith and Stahler are the producers of the calendars that have your dander up? Perhaps they were produced by others who allegedly forgot to put NPS markers on the calendar photos.

        Too much ado about nothing other than envy on your part it appears. And as Ralph accurately said, the photos are public property and you can get copies if you ask, but you can’t claim credit for them.

  10. Richie G Avatar
    Richie G

    Very interesting results I hope it helps not only learning more about wolves,but also helps tp protect them as a species. I also like to add that the research doesn’t go against the wolves,that hunters will go after the strongest and the biggest they can get,thinking it will kill off the species.

  11. Richie G Avatar
    Richie G

    opps to


Dr. Ralph Maughan is professor emeritus of political science at Idaho State University. He was a Western Watersheds Project Board Member off and on for many years, and was also its President for several years. For a long time he produced Ralph Maughan’s Wolf Report. He was a founder of the Greater Yellowstone Coalition. He and Jackie Johnson Maughan wrote three editions of “Hiking Idaho.” He also wrote “Beyond the Tetons” and “Backpacking Wyoming’s Teton and Washakie Wilderness.” He created and is the administrator of The Wildlife News.

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