On Sept. 6, 2019, the U.S. Fish and Wildlife Service (USFWS) rejected a petition to designate the bison population in Yellowstone National Park a threatened or endangered species under the Endangered Species Act (ESA). USFWS previously rejected the petition in 2016, but it was remanded for reconsideration by a judge in 2018.
In the September 2019 decision, USFWS found that the petition “…does not present substantial scientific or commercial information indicating that the petitioned action may be warranted.” As a result of this decision, USFWS will not list the Yellowstone bison as an endangered species.
I wrote about bison and the ESA in the April 22, 2019 WLJ and described problems with the science claims in the petition to designate the Yellowstone bison an endangered species. The most obvious problem is that the Yellowstone bison are simply a population and not a species, but the ESA definition of species includes subspecies and populations (called distinct population segments-DPS). This is a serious issue because subspecies and populations are not scientifically definite, and the original intent of the ESA was to preserve species, not subspecies and populations.
Another claim in the ESA petition is that the Yellowstone bison are some of the only bison without residual cattle genes from past interbreeding of cattle and bison. This is not scientifically established, and a few cattle genes in bison are probably unimportant to bison characteristics, fitness, and behavior.
A third claim in the ESA petition is that the Yellowstone bison consist of two genetically distinct herds (central and northern herds) which should be considered separate populations. The genetic research used to support this (see Halbert et al. 2012 in the references) shows the two herds have been separate breeding groups for several generations, but there is some interchange between them, primarily bulls.
However, the ESA petition and the judge’s 2018 opinion do not adequately acknowledge this finding and another scientific paper that shows emigration from the central herd to the northern herd (see Fuller et al. 2007 in the references). In other words, the two herds within Yellowstone are not entirely separate or genetically distinct. Like most wildlife populations, the bison in Yellowstone have groups in different areas that mix over time. This is widely recognized in wildlife management resulting in the game management units used by states in hunting regulations. Petitioning for an ESA listing because there are bison in different areas of the park is not justified.
Perhaps the most important fact is that the Yellowstone bison are not endangered with extinction. There are about 4,500 bison in the park. Also, the Yellowstone bison are infected with brucellosis which is a threat to livestock and other wildlife.
Note that the petition for an ESA listing of the Yellowstone bison relies heavily on genetic considerations:
• The Yellowstone bison are a distinct population segment;
• The Yellowstone bison are free of cattle genes and therefore “genetically pure”; and
• The Yellowstone bison consist of two genetically separate herds.
These claims are basically opinion based on selecting indefinite science to make a case for ESA listing.
What you can do
The Yellowstone bison ESA petition relies largely on genetic arguments. Livestock producers and scientists in the USDA and agriculture departments in the land-grant state universities have a thorough understanding of applied genetics. You can provide information about genetics to the state and federal wildlife agencies and ask your USDA and university colleagues to help in these efforts. This can improve the science in future ESA cases involving bison and other species. Recall that the sage grouse ESA decision in 2010 also involved genetics and speculative predictions of extinction due to inbreeding in populations isolated by agriculture and energy development.
The good news is that the USFWS made a good decision, supported by science, to deny the ESA petition to list the Yellowstone bison population. This follows positive changes to the ESA in August by the secretary of the interior (see WLJ August 19, 2019). You can tell your local people in the Department of the Interior—Bureau of Land Management, USFWS—and USDA that these actions with the ESA are appreciated. You can offer them your knowledge of genetics and wildlife to continue to improve implementation of the ESA.
There will likely be more ESA petitions for bison in Yellowstone and other areas as interest in establishing wild bison increases (see WLJ March 4, 2019, Mott 2019, and Skinner 2019 in the references). Also, a sage grouse ESA reassessment is due in 2020. Proactive input from the livestock community can help prevent unjustified ESA listings of these and other species. — Dr. Matthew Cronin
(Matthew Cronin was a research professor at the University of Alaska and is now at Northwest Biology Company LLC and an affiliate professor at Montana State University. He can be reached atcroninm@aol.com.)
Fuller, J.A. R.A. Garrott, and P.J. White. 2007. Emigration and density dependence in
Yellowstone bison. Journal of Wildlife Management, Volume 71, Issue 6, Pages 1924-
1933.
Halbert, N.D., P.J.P. Gogan, P.W. Hedrick, J.M. Wahl, and J.N. Derr. 2012. Genetic population
substructure at Yellowstone National Park. Journal of Heredity, Volume 103, Issue 3, Pages 360-
370.
Mott, R.C. 2019. American Prairie Reserve. Range Magazine, Summer 2019, Page 80.
Skinner, D. 2019. Critical Mass: Cowboys or buffalo? Range Magazine, Fall 2019, Pages 16-31.
https://www.regulations.gov/document?D=USFWS-R6-ES-2019-0085-0001
For information on the Yellowstone Bison ESA case contact the U.S. Fish and Wildlife Service at 303-236-4258.
