A Blueprint for Continued Wolf Restoration and Recovery in the Lower 48 States
Wolf conservation is at a crossroads.
The U.S. Fish and Wildlife Service (FWS), states and others are making decisions critical to existing populations of our nation’s native wolf species and to efforts to restore them in additional areas. By the time the Endangered Species Act (ESA) banned the killing of wolves in 1973, they were nearing extinction in the lower 48 states. Today, thanks to reintroduction programs, gray wolves are back in the Northern Rockies, a small population of Mexican gray wolves is established in the Southwest, and red wolves are slowly making progress in the Southeast. Federal protections have allowed wolves to naturally expand from Minnesota to Wisconsin and Michigan in the Great Lakes region.
Defenders of Wildlife has been a leader in the restoration and innovative conservation efforts that have put wolves back on the landscape. Working side by side with ranchers and local officials, our field staff has implemented non-lethal management practices that allow wolves and livestock to coexist side by side. Our scientists and policy experts have promoted management strategies and policies that enable wolves to thrive in their natural habitat. Through our legal, advocacy and outreach capabilities, we have been instrumental in setting wolves on the path to restoration and recovery, allowing them to reclaim their vital role in maintaining the health of the landscape.
While we celebrate the progress made to date, serious threats to wolves remain. We must be even more vigilant and keep up our fight against unscientific management practices and policies that set back the restoration of the species and threaten Defenders’ vision for wolf conservation in the lower 48 states.
Defenders’ Wolf Conservation Vision
Wolf populations are distributed across appropriate suitable habitat, with each population large enough to maintain critical interactions between wolves and ecosystems.
The Science Behind Our Vision
To guarantee the long-term survival of wolves, not only must we restore these predators in multiple suitable areas, but we must do it in numbers large enough to protect wolf populations from natural and human-caused disasters and with enough connectivity to other wolf populations to provide for essential dispersal and gene flow. These basic requirements for wolf restoration are rooted in five biological concepts that guide successful wolf recovery and Defenders’ vision and plan of action for achieving it.
Natural selection shapes the genetic makeup of species in close association with the environments they inhabit. Successful long-term conservation means saving species in the fullest possible representation of suitable and appropriate environments in which they historically occurred.
The gray wolf’s pre-Columbian distribution in North America extended throughout the continent, from the low Arctic of Canada and Alaska in the north to the high plateau of central Mexico in the south. Within this range, wolves occupied various habitats and preyed on a variety of species: caribou and moose in the Arctic; moose and deer in the Great Lakes; elk and deer in the Rocky Mountains; bison on the prairie. Restoration requires healthy wolf populations in our remaining wild ecosystems where wolves are a key missing component.
To be sustainable over the long term, wolf populations must be sufficiently resilient to the range of threats they routinely face throughout their range. Certain behaviors and life history traits historically enabled wolves to survive and adapt despite fluctuations in prey, disease, competition among packs and with other large carnivores and intense pressure from human development. Traits that enhance resiliency include prey and habitat flexibility, high rates of producing pups and the capacity to disperse widely—sometimes hundreds of miles—in search of prey and unoccupied territory.
The pace and scope of the use of deadly poisons, traps, aerial gunning and other lethal measures unleashed on wolves by modern man undermined their resiliency. Consequently, wolves were eradicated from almost all of their range in the continental United States. Restoring wolf populations at high enough densities in appropriate suitable habitat throughout their historical range bolsters their resiliency to the many threats they face.
Imperiled species conservation requires redundancy—recovered populations in multiple areas—as a hedge against the catastrophic loss of any single population. Disease, severe weather events, fire or drought can wipe out entire populations. Redundancy ensures that these losses do not jeopardize the species or subspecies as a whole. For wolf recovery and the protection of individual populations, we must build redundancy into restoration efforts.
Ecologically functional populations
In the early 20th century, Aldo Leopold, one of the first American scientists to recognize the value of “land health,” warned of the consequences of removing wolves. and other keystone predators. Recent research has shown the wolf to be a “strongly interactive species,” meaning its interactions with other animals contribute substantially to the maintenance of habitat and biodiversity. The disappearance of such a species leads to profound changes in ecosystem composition, structure and diversity (Beschta and Ripple 2012; Ripple and Beschta 2004, 2011; Estes et al. 2011; Soulé et al. 2003; Terborgh et al. 1999; Schmitz et al. 2000). Maintaining ecologically functional wolf populations—populations of sufficient density and distribution—is fundamental to the health of our native ecosystems.
Advances in population ecology and genetics make clear the importance of connectivity among wildlife populations. Isolated animals can develop genetic abnormalities that weaken the species. Michigan’s Isle Royale in Lake Superior provides a noteworthy example. Scientists conducting long-term studies of the wolf population there found that due to extreme inbreeding, 58 percent of the island’s wolves have spinal malformations (Räikkönen et al. 2009), which can reduce their chances of survival. Dispersal corridors allow for the exchange of genes among populations and are critical to long-term viability.
- Beschta, R. L., and W. J. Ripple. 2012. The role of large predators in maintaining riparian plant communities and river morphology. Geomorphology 157-158: 88-98.
- Estes, J. A., J. Terborgh, J. S. Brashares, M. E. Power, J. Berger, W. J. Bond, S. R. Carpenter, T. E. Essington, R. D. Holt, J. B. C. Jackson, R. J. Marquis, L. Oksanen, T. Oksanen, R. T. Paine, E. K. Pikitch, W. J. Ripple, S. A. Sandin, M. Scheffer, T. W. Schoener, J. B. Shurin, A. R. E. Sinclair, M. E. Soulé, R. Virtanen, and D. A. Wardle. 2011. Trophic downgrading of planet Earth. Science 333: 301-306.
- Räikkönen J., J. A. Vucetich, R. O. Peterson, and M. P. Nelson. 2009. Congenital bone deformities and the inbred wolves (Canis lupus) of Isle Royale. Biological Conservation 142: 1027-1033.
- Ripple, W. J., and R. L. Beschta. 2004. Wolves and the ecology of fear: can predation risk structure ecosystems? BioScience 54(8): 755-766.
- ---. 2011. Trophic cascades in Yellowstone: the first 15 years after wolf reintroduction. Biological Conservation 145: 205-213.
- Schmitz, O. J., P. Hambäck and A. P. Beckerman. 2000. Trophic cascades in terrestrial systems: a review of the effect of top predator removals on plants. American Naturalist 155: 141-153.
- Soulé, M. E., J. A. Estes, J. Berger and C. M. Del Rio. 2003. Ecological effectiveness: conservation goals for interactive species. Conservation Biology 17: 1238-1250.
- Terborgh, J., J. A. Estes, P. Paquet, K. Ralls, D. Boyd-Heger, B. J. Miller and R. F. Noss. 1999. The role of top carnivores in regulating terrestrial ecosystems. Pp. 39-64 in: M. Soulé and J. Terborgh, eds., Continental Conservation: Scientific Foundations of Regional Reserve Networks. Washington, DC: Island Press. 238 pp.