Study indicates 5000 mature individuals are needed for population viability

Conservation Targets Too Small To Stop Extinction
RedOrbit

This determination could have profound implications for the protection of many species. Many biologists use a number of 2000 individuals in a population for maintenance of viable populations over the long term. In the Northern Rockies the USFWS believes that 1600 (and declining) wolves represent a viable population that can persist over the long term. The National Park Service presumes that maintaining only 2300 bison in Yellowstone will maintain the genetic diversity needed for long term viability. According the USFWS even fewer grizzlies are needed for recovery with 500-600 bears in the Yellowstone DPS.

According to the new study:

“populations of endangered species are unlikely to persist in the face of global climate change and habitat loss unless they number around 5000 mature individuals or more”

Grizzly Bear, Buffalo, Wolf © Ken Cole

Grizzly Bear, Buffalo, Wolf © Ken Cole

avatar
About The Author

Ken Cole

Ken Cole, Buffalo Field Campaign's Executive Director, is a 5th generation Idahoan, an avid fly fisherman, wildlife enthusiast, and photographer. He was formerly the Idaho Director for Western Watersheds Project.

9 Responses to Conservation Targets Too Small To Stop Extinction

  1. avatar Maska says:

    Thanks for the post, Ken. Future recovery planning (for example, for the Mexican gray wolf) needs to take this work into account in setting population goals.

  2. avatar Virginia says:

    To me, this begs the question, “why are we basing current plans to avoid extinction on conditions that are no longer relevant?”

  3. I spent the day in the Lamar Valley here in Yellowstone. The Druid Pack chased an elk (cow or large calf) into the Lamar River where the elk eluded the pack as they swam after the elk for some time. The elk did a marvelous job of eluding the wolves. I ended up cheering for the elk. When I left just before dark, the elk was still in the river and the wolves were scattered in the grass 20-50 yards away.
    The wolves all had mange and almost no hair on their tails. I find it strange that the park allows darting of wolves to put radio collars on them but will not allow darting them to pour insecticide on their backs to eliminate the mange mites. Not natural.
    Ken- Bison genetic viablity in Yellowstone can be maintained by bringing in bison from other sources. I think the main objective with bison and elk in Yellowstone should be maintaining a heathly range for all range users. The actual numbers should be based on the measured carrying capacity. I saw a lot of bison today and the range looks great. Wolves can also be brought in to provide genetic variety. I think we should cocentrate on maintaining the wolves we have and not be concerned with trying to get the numbers up to 5000.

  4. avatar Eric T. says:

    aribitrary numbers
    arbitrary and capricious agruments
    yep, the math adds up all right.

  5. avatar Ken Cole says:

    What other sources are there? All of the other sources, with the exception of the Henry’s Mountain herd in Utah, have documented cattle genes. They also only number around 700 so, combined, they number about 4000 until another big slaughter occurs and they have no connectivity to maintain genetic viability.

    Besides, there is no proposal to do what you suggest. In essence Yellowstone bison are genetically isolated and the slaughter does not select for a random sample of the population so genetic variability is not maintained.

    With this information it seems apparent that bison should not be confined to just the Park, they should be allowed to use public lands outside of the Park. Even when bison numbered 4900 the range looked good. That’s not the limiting factor. The limiting factor is winter range. The range can sustain much higher numbers if they are allowed to leave the Park during winter. During the winter the range inside the Park is covered with snow and is protected from overgrazing by bison. It’s not that there isn’t enough forage to sustain them in the Park during the winter it’s that they can’t physically get to it through the snow and ice.

  6. avatar JimT says:

    Thanks for the link, Ken

  7. avatar Ryan says:

    “In the Northern Rockies the USFWS believes that 1600 (and declining) wolves represent a viable population that can persist over the long term.”

    Ken,

    The wolves will be just fine due to the inflow of genetics from canada.

  8. avatar gline says:

    not if they are being killed off

  9. avatar Ken Cole says:

    The wolves just north of the Canadian border, to my understanding, are quite low in density. They have isolation issues just like those in the lower 48 so it’s hard to say that they can contribute much to US populations.

Calendar

October 2009
S M T W T F S
« Sep   Nov »
 123
45678910
11121314151617
18192021222324
25262728293031

Quote

‎"At some point we must draw a line across the ground of our home and our being, drive a spear into the land and say to the bulldozers, earthmovers, government and corporations, “thus far and no further.” If we do not, we shall later feel, instead of pride, the regret of Thoreau, that good but overly-bookish man, who wrote, near the end of his life, “If I repent of anything it is likely to be my good behaviour."

~ Edward Abbey

%d bloggers like this: