Gray_wolf_(female). Photo by D. AVery, Wikimedia Commons
(Click on the following link to listen to an audio version of this blog … Colorado Wolves
Back in November, 2020 I voted for the first time as a new citizen of the state of Colorado. One of the items on the ballot was an initiative entitled “Proposition 114.” Proposition 114 basically asked the question, “should gray wolves be re-introduced to mountains of Colorado?”
Taking a question like this to voters was an idea that had never been tried before. Some opponents of this proposition disparagingly referred to it as “ballot biology,” but the science behind the re-introduction was solidly built into the proposition. The intent of this vote was to assess the willingness of the people of Colorado to once again have gray wolves roaming around on the western slopes of the Colorado Rockies. Before the vote, public opinion surveys indicated an 80% approval rating for wolf re-introduction. The actual vote, however, was much closer. The proposition passed but only by a razor thin margin of less than 1%!
Proposition 114 required that the Colorado gray wolf re-introduction begin before the end of 2023. Wildlife biologists worked hard to develop a plan and a set of locations for the wolf re-introduction and line up approval from the U.S. Fish and Wildlife Service. Ranchers and a number of other interest groups worked equally hard to cancel or delay the re-introduction. Ignoring the science behind the proposition, the program was politized into a Left vs. Right, Liberal vs. Conservative, Democrat vs. Republican dispute.
A number of Republican-controlled states (Montana, Wyoming and Utah) refused Colorado’s request for wolves. Finally, Oregon agreed to trap and transport wolves for the Colorado program. Legal disputes and court battles went on until mid-December 2023!
Gray Wolf. Photo by USFWS. Public Domain
The final court decision came down in favor of the wolf release, and on December 18, 2023, with 45 people on hand to watch (including Jared Polis, the governor of Colorado) five wolves captured just the day before in Oregon, were released in the mountains of Grand County, Colorado.
The five released wolves included two, one-year old sibling pairs (male and female siblings) and a two-year-old male. The wolves left their cages in very different manners: a few bolted out of the cages and ran straight for cover of a nearby forest, a few lingered in their cages and seemed to finally come out with great reluctance. One of the females stayed in her opened cage for so long that several people (including Gov. Pollis) went over and looked into the open cage door. Eventually, though, all of the wolves left their cages and ran out into surrounding forest.
However, as John Ewen, a conservation biologist with the Zoological Society of London, put it in an interview with The Scientist: “The opening of the cage door is just the beginning of a very long journey to recovery.” Over the next five years between thirty and fifty wolves will be released in the Colorado mountains. Their locations, pack sizes and activities will be monitored closely by the state’s wildlife biologists. These new “Colorado wolves” will fill-in the “wolf-less” open space in the north-south mountainous stretch between Mexico and Canada. Wolves now live all across the backbone of America!
Inevitably, the wolves will kill livestock. There is a generous compensation plan to try to help reduce the economic impacts of wolf-kills on Colorado ranchers. Payments up to $15,000 per animal will be made in the case of livestock deaths.
Gray wolf. Photo by HFSchwartz, Forestry Images
The whole idea of putting species back into the ecosystems where they once were integral components is relatively new. In particular, the re-introduction of large predators, animals that were routinely and enthusiastically annihilated with guns, traps and poisons, is extremely controversial. The science that enumerates the benefits of adding predators to a biotic community has been developing and growing over the past 60 years, but the deeply felt emotional reaction against large, predaceous animals is something that is difficult to overcome by logic alone.
Prior to the late 1950’s is was accepted in conservation biology that large predators were for the most part undesirable components of ecosystems. Not only did they threaten both human lives and livestock, but they also harmed wild, grazing animals and added little to the overall sustainability or vigor of a biotic community. Herbivore populations and plant populations were obviously and intricately interconnected and highly controlled, but predators had only negative impacts on their ecosystems. There would be more deer for deer hunters, the logic went, if there were no cougars or wolves. The ecosystems would be more productive and more robust if the “killers” were only removed.
Gray_Wolf. Photo from httpknowledgebase.lookseek.comGray-Wolf-Canis-lupus.html, Wikimedia Commons
And removed they were! Funded by bounties on large predators like wolves and cougars (and also smaller predators like coyotes (see Signs of Spring 3, March 19, 2020)) federal and state programs drove these predators out of their traditional geographic ranges and, in some cases, pushed them right up to the brink of extinction.
So, when did the importance of predators in biotic communities begin to be recognized? One significant landmark was a paper published in The American Naturalist in 1960 by Nelson Hairston, Frederick Smith and Lawrence Slobodkin. The paper, entitled “Community Structure, Population Control, and Competition,” explored the idea that the sizes of herbivore populations in an ecosystem were not simply controlled by the abundance of vegetation, but that predator species were, in fact, extremely important in regulating the populations of the herbivores. Further, predator species via their impacts on herbivore numbers were important protectors of vegetation. “Why is the world green?” they were, in effect, asking. Their answer was because there were predators!
Experimental observations followed the publishing of the “Community Structure…” paper. A student of Frederick Smith, Robert Paine, conducted an experiment on the rocky shores of Washington State. A complex, intertidal community of barnacles, mussels and limpets also contained the predaceous starfish, Pisaster ochraceus. Paine removed the starfish from one section of the coastline and monitored the changes in the community. After a year, the starfish’s primary prey, the barnacle Balanus glandula, had greatly increased in numbers in the starfish-less communities along with several fast growing mussel species. The species richness of the communities without the predator starfish, though, decreased from fifteen species to just eight! The predator was a keystone species that helped to maintain species richness and community stability.
Another early study looked at sea otters and the great kelp forests around the Alaskan island of Amchitka. Fur traders had decimated the sea otter populations in the waters around this island. The kelp forests, consequently, were overrun by sea urchins since there were no sea otters to prey upon them. The sea urchins overgrazed the kelp and thinned and degraded the entire vegetative community. The term “trophic cascade” was later applied to the destructive, rippling impact of the removal of a top predator throughout the trophic levels of a community.
Grey_wolves. Photo by R. MacDonald, Wikimedia Commons
The effect of a predator in a community can be quite subtle. Predators can influence the feeding patterns, behaviors and abundance of prey species even without any direct killing of the prey species. An experiment with spiders (Pisaurina mira) and grasshoppers ( Melanoplus femurrubrum) showed the mere presence of the spiders (their mouthparts were sealed shut in the experiment) could cause the grasshoppers to forego feeding in some cases to the point of starvation. Consequently, the grasses in the systems which contained the non-feeding spiders, flourished! Fear of the predators generated a “behavioral trophic cascade” (also called a “fear cascade”) that allowed the community to stabilize and flourish.
Fear cascades also explained the observations on nesting behaviors and clutch sizes in song sparrows (Melospiza melodia) when recordings of racoons or predaceous birds were played near the nesting sites. Clutch sizes decreased by 40% when these auditory clues of a predator’s presence were played. This paper was published in Science in 2011.
The removal of a large predator also allows small to medium sized predators to greatly increase in numbers. I discussed this in a previous blog (Signs of Spring 11, May 16, 2019). These small predators can have devastating impacts on small mammal, bird, reptile and amphibian populations and can greatly disrupt the diversity and stability of an ecosystem.
Radio_collared_gray_wolf_on_snow. Photo by USFWS, Public Domain
Wolf re-introductions in New Mexico and Arizona (Mexican gray wolf) and Yellowstone National Park (gray wolf) have had expected impacts on prey herds and vegetative ecosystems. Red wolf re-introductions in North and South Carolina have had limited ecological impacts because of habitat fragmentation, coyote predation and interbreeding, vehicle collisions and uncontrolled poaching. The red wolf population in this area went from 130 individuals in 2000 to just 10 individuals in 2010.
Putting a large predator back into a biotic community is a complex task. The quality of the habitat, the new nature of the area’s climate, the presence of invasive plants and animals, and the response of potential prey species to the presence of a predator about whom they have grown quite naïve and just a starting list of factors to consider and evaluate. Also, the presence and proximity of humans (who are often referred to in the ecological literature as a “hyper-keystone species”) also will change the behaviors and potential success of re-introduced predators. People have to be included in the biotic community matrix in order to predict the outcomes of large predator re-introductions.
I will keep you updated on the Colorado wolves! Keep your paws crossed that they succeed!