Wolves: Part Three; Invasive Species

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U.S. Executive Order 13112 (1999) defines “invasive species” as “an alien species whose introduction does or is likely to cause economic or environmental harm or harm to human health.”

Gray wolf populations were extirpated from the western United Stated by the 1930s. The public attitudes towards predators began to change and in 1973 wolves received legal protection with the passage of the Endangered Species Act (ESA). Wolves soon became the poster child for the ESA, showing up on billboards, t-shirts and posters. Many “documentaries” were made about wolves using information we thought we knew about wolves. Leading biologist did study after study on wolves, and wrote several books on their research. The problem was this research was not done on wolves in the wild, but on captive wolves. You won’t learn much about the natural behavior of wolves by jailing a group of strangers on a tiny surface area and watching them, except maybe that they are so tolerant and social that they still don’t kill each other. Dr. L. David Mech, just about the greatest living authority on wolves, put it in a nutshell with these words: ‘Such an approach is analogous to trying to draw inferences about human family dynamics by studying humans in refugee camps.’

Our wolves were making a comeback on their own, traveling down from southern Canada, where they had managed to survive. In 1994, biologist determined that there was only on species of wolf, Canis Lupus. After years of planning and studies and over the objections of a majority of the citizens affected, the US Fish and Wildlife Service (USFWS) went ahead with plans to help “jumpstart” wolf recovery. In 1995 and 1996, 66 wolves were captured in Alberta and British Columbia, Canada for introduction into Yellowstone National Park and parts of Central Idaho. Working with the Canadian Government, it was determined that wolves for reintroduction should come from relatively abundant populations that had experience at hunting elk and bison, the two major prey species in Yellowstone National Park that were considered overly abundant. The Alaska Department of Fish and Game sent two pilots and two biologists to help with wolf capture and they were impressed by the large size of the wolves and their similarity to Alaskan wolves. The largest males weighed around 147 pounds.

In 2012, using newly available genetic information in addition to existing morphometric data, research biologists with the US Fish and Wildlife Service completed an extensive review of wolves in North America – the third comprehensive review since 1944. All four researchers support the view that there are three subspecies of wolves recognized in western North America and that a single subspecies (Canis lupus Nubilus) inhabited the entire western states north of Arizona and New Mexico, and southern Alberta, southern British Columbia and Southeast Alaska.

A considerably larger northwestern wolf (Canis lupus Occidentalis) occupied northern Alberta, British Columbia, Yukon, and the rest of Alaska. This wolf has always been common and its distribution has never been appreciably affected by human activity. The northwestern wolf evolved in northeast Asia and Beringia during the Wisconsin Glaciation, while smaller subspecies of wolves developed south of the ice sheets.

The third subspecies of wolf in western North America, the Mexican wolf (Canis lupus Baileyi), is the only subspecies that was ever truly endangered, having died out in the wild in Sonora in the 1970s. It is currently being reintroduced from captive animals into northern Arizona and New Mexico.

The original wolf of the western states was 20-25% smaller, with large males seldom exceeding 110 pounds and the largest recorded being 125 pounds. The skull size of the northwestern wolf is also about 4-6% larger than that of the plains wolf. The evidence is pretty clear that the subspecies of wolf brought to the western states for reintroduction is not the same wolf that historically lived here, and the term “reintroduction” does not apply. What does apply is “introduction,” and the introduction was that of a non-native species.

“An introduced species might become invasive if it can out-compete native species for resources, such as nutrients, light, physical space, water or food. If these species evolved under great competition or predation, the new environment may host fewer able competitors, allowing the invader to proliferate quickly.”

The Mackenzie Valley Wolf (Canis Lupus Occidentalis) was the subspecies used in the Yellowstone and Idaho introduction effort. Mackenzie Valley Wolves typically stand about 32–34 inches at the shoulder and males weigh between 100 and 175 pounds with unconfirmed reports of wolves weighing up to 230 pounds. The Mackenzie Valley Wolf’s thick, long limbs are proportionally built for traversing through rough terrain such as deep snow or the cliffy edges of the Rocky Mountains. Its deep chest hosts large lungs, letting the wolf breathe more efficiently at higher altitudes, and allowing it to exert huge amounts of stamina traveling up to 70 miles in one day. Its powerful neck is a very important adaptation; it has to be strong to support the wolf’s large head and is crucial for bringing down prey. The skull is 12 inches long and is armed with an impressive array of large teeth which, when coupled with huge jaw muscles, give it an incredible bite force that is strong enough to break the bones of prey and even crack the femur of moose.

“While all species compete to survive, invasive species appear to have specific traits or specific combinations of traits that allow them to out-compete native species. In some cases the competition is about rates of growth and reproduction. In other cases species interact with each other more directly.”

Common invasive species traits include:

Fast growth

Rapid reproduction

High dispersal ability

Phenotypic plasticity (the ability to alter growth form to suit current conditions)

Tolerance of a wide range of environmental conditions (Ecological competence).”

The larger sub-species of wolf were introduced into an environment where there was very little competition, and they easily won over the much smaller native wolf. The elk, moose, and other ungulates (herd animals), had no experience with an apex predator. Without an apex predator like the wolf, they lost their fear and inborn instinct to survive, and their behavior over the years had changed. They had become languid and were easy targets for the Mackenzie Valley wolf. They were easy prey and because of their abundance, these wolves quickly took on invasive species traits.

In a normal environment, wolf packs are led by a male and female, once called the Alpha pair, we now understand that this alpha pair is really mom and dad, and the pack consists of their offspring, and maybe an aunt and uncle thrown in the mix. Mom goes into estrus once a year, and the pack helps raise the litter of 4 to 6 pups. When prey is abundant though, sometimes a second or even third female will go into estrus and soon we have a lot more pups which eventually grow to become full-fledged pack members on their own. Traditional packs might consist of 6 to 12 members, these larger packs have been known to reach 20 to 30 members, with the largest packs known to have reached up to 38 members (as with the infamous Yellowstone Druid Pack). Now we have huge packs able to take down large animals, and needing to take down more to feed the pack. Add to that the fact that they also have a lot of adolescent wolves in the pack who are not allowed to hunt with the pack until they have been trained. Adult pack members take the adolescents out in groups to teach them how to hunt. These hunts are probably responsible for most of the “thrill kills” or other kills that hunter, ranchers, and farmers have recounted. Because these wolves are not hungry and just practicing, they sometimes kill and leave, or sometimes just leave the animal mortally wounded and left to die. As sad as this is, the wolf should not be blamed for this… they don’t know any better.

As the ungulate herds thin out or become harder to find, these large packs still need to survive, so they turn to other prey. Unfortunately, most of the “other” prey is in the form of cattle, sheep, and horses. Dogs, used to hunt and dogs used to protect these herds are no match against a pack of large wolves. Wolves see dogs as competition, and will normally kill most dogs they find (there are always exceptions). Wolves have been observed baiting guard dogs. One wolf will harass and entice the dog to chase. The wolf will then lead the dog into an ambush by the rest of the pack.

These wolves have wandered into people’s back yards and kill their pets, because they had very little to fear from humans because of the Endangered Species Act. Now that they have been delisted from the Act, and are being hunted, they will quickly learn and adapt, but I believe they will survive. That twelve-inch skull holds more than massive teeth. It holds a large brain allowing these wolves to adapt to most situations rather quickly.

I actually admire these wolves for their intelligence and their adaptability, but those are the very traits that can make them a very successful invasive species, and that might have a larger destructive impact on the ecosystem than we ever thought possible. Somehow, we have to come together as citizens and quit attacking each other and work together. Neither side will be 100% right, and each side will have to give… it’s called compromise, and it’s what keeps this country strong!