“If it looks like a wolf, acts like a wolf, then it’s a wolf”: The Absurdity of Distinct Population Segments

On November 13, 2025 By Steve Busch

Endangered species protections in the United States were first introduced over 120 years ago when concerns about the disappearance of passenger pigeons motivated Congress to create the “Lacey Act of 1900”.

Sixty-six years later, Congress passed the “Endangered Species Preservation Act”, a law that underwent several revisions before being scrapped in favor of what we now call, the “Endangered Species Act” (ESA).

The ESA has also undergone revisions since it was passed in 1973. Like previous laws intended to prevent animal extinctions, the ESA is imperfect and open to legal wrangling and judicial interpretation. Continuous litigation over its intent, word smithing, and vagaries of implementation, have created intense controversy and ongoing conflict.

The problem with the ESA is that there are multiple words, phrases, and definitions that are vague and non-discerning. Some of the concepts written into the ESA are not supported by research. Disputes over taxonomical classifications and ambiguous wording continue to thwart the implementation of common sense science based policies.

One such example is the debate over what constitutes “a significant portion” of a species range. Estimates of a species historic range compared to its current range are not supposed to influence whether or not a particular species warrants protection. Yet it does, as exemplified by how both grizzly bears and gray wolves continue to be protected based on their historic ranges and political boundaries rather than on the species biological health, their global range, and their actual population. (See my 2017 blog article, “What’s Wrong with The ESA?”)

Under the ESA, the U.S. Fish and Wildlife Service has a mandate to use the best available scientific or commercial data in making a ruling as to whether a specific taxon merits listing for legal protections. Most folks learned in high school biology that a species is defined as a group of animals that can interbreed with others of its kind and produce viable offspring. The species level has always been the basic fundamental category for taxonomic classification.

However, the writers of the ESA chose to muddy the waters by creating something called, “Distinct Population Segments”. This newly created taxonomic category further divides species into arbitrary sub-groups based on minor morphological variations exhibited by isolated regional populations.

In the case of the gray wolf, this has led to the protection of the “Red” wolf on the east coast, the “Mexican” gray wolf in the American southwest, and the “Rocky Mountain” gray wolf in our northern states. These so-called DPS categorizations were created despite research showing extensive hybridization among the subject populations, including genetic mixing with coyotes and dogs.

The assignment of a Distinct Population Segment label is a wholly arbitrary categorization because it embraces some of the morphological differences among wolves while ignoring a similar level of differentiation identified in dozens of regionally isolated wolf sub-groups.

Historically speaking, multiple varieties of wolves were noted by the Lewis and Clark expedition as they journeyed west. According to Lewis’s observations, northwest wolves varied in appearance and were somewhat smaller than the wolves he was familiar with on the east coast. In his journal, Captain Lewis noted that wolves were observed by Corps members on 59 different days. Although some of these wolves may have looked a little different from region to region, one thing remained constant. All the wolves which the Corps of Discovery encountered exhibited the same wolf-like behavior, including several instances of aggressive attacks on Corps members and their livestock. This behavior prompted members of the expedition to shoot some 36 wolves over their 28 month journey.

The Canadian sourced wolves that were translocated in 1995 into Wyoming and Idaho were larger than the wolves described as inhabiting the region by Lewis and Clark in 1804-5. Ironically, these larger Canadian wolves are now called “Rocky Mountain” wolves and have been given their own DPS by agency bureaucrats. This does not mean that these wolves are a different species than the wolves that may have been present in the region prior to 1995. No, on the contrary, regardless of their geographical distribution or variations in size or coloration, all wolves, throughout all of recorded history, in all regions of the world, are the same species.

Wilson and Reeders authoritative volume on taxonomy “Mammals of the World” lists one species of wolf and multiple sub-species.

All of the animals listed above can, and will, interbreed if given the opportunity, and will produce fertile offspring as verified by direct observation and confirmed by genetic sampling. This fact alone is sufficient to refute the idea that each of these animals is a different kind, or that any one variety of wolf should receive special consideration as a “Distinct Population Segment”. It would be like dividing human beings into different sub-species based on body size, leg length, hair color, or skin pigmentation.

It is ironic that Colorado voters mandated wolf introduction and brought Canadian sourced wolves into the state. These wolves now pose a direct threat to the USFW’s carefully planned “Mexican” wolf DPS in Arizona and New Mexico. It is inevitable that these two “kinds” of wolves will begin interbreeding as both wolf populations are expanding and will soon overlap each other’s ranges.

The Endangered Species Act should be revised based on the inability to define an endangered animal without using lines drawn on a map or clarifying the common scientific meaning of the word “species”. That could be a task that is easier said than done because even taxonomists and evolutionary biologists cannot seem to agree on a definition of the word “species”. The ESA goes even further off the rails when implementing protections based on sub-divisions that go beyond the species level when there is no rational scientific justification for doing so.

To conclude this little rant, let me just say that research into wolf genetics has proven that there is no such thing as a “pure” wolf. Gene sampling has confirmed that extensive hybridization of the wolf genome has occurred throughout history in all regions of the world. This means that minor morphological differences are attributable to inbreeding resulting from genetic isolation as well as differences in diet and other environmental factors.

To put this all into perspective, Nature Magazine recently published research supporting the linked ancestry of wolves and dogs, which are both classified as Canis lupus. Here’s a quote from the Nature article: “We analysed 72 ancient wolf genomes spanning the last 100,000 years from Europe, Siberia and North America. We found that wolf populations were highly connected throughout the Late Pleistocene, with levels of differentiation an order of magnitude lower than they are today.”

Yeah, you read that right, “lower than they are today”. That means varietal differentiation in the wolf genome was almost non-existent in the past, but has increased significantly over the last few centuries or so. This relatively recent increase in differentiation is obviously a direct result of man’s impact on wolf range, distribution, and habitat fragmentation. Disruption in connectivity caused by human development and activity has resulted in decreased mixing between isolated regional wolf populations. Isolation leads to increased inbreeding, which results in minor regional variations among wolves. That said, gray wolves continue to enjoy the widest circum-polar range of any large terrestrial predator on the planet. They are not, and have never been, an endangered species

The truth of the matter is this: If it looks like a wolf, acts like a wolf, then you can be rest assured, it’s a wolf.

Sources for this article include:

https://www.press.jhu.edu/books/title/8864/mammal-species-world

https://www.nature.com/articles/s41586-022-04824-9

https://en.wikipedia.org/wiki/Lacey_Act_of_1900

https://www.fws.gov/esa50/our-history/pre-1973

Click to access endangered-species-act-accessible_7.pdf

https://www.frontiersin.org/journals/conservation-science/articles/10.3389/fcosc.2022.971280/full

https://oldmanoftheski.com/?s=What%27s+wrong+with+the+ESA

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