https://www.sciencedaily.com/releases/2017/08/170829091032.htm
Wolves will take the easier to kill Caribou over the tougher Moose
Following the reduction of moose using sport hunting, wolf number numbers declined, with wolf dispersal rates 2.5 × greater than the reference area, meaning that dispersal was the process leading to fewer wolves. Caribou annual survival increased from 0.78 to 0.88 for the Columbia North herd, located in the moose reduction area, but survival declined in the reference area (Wells Gray). The Columbia North herd probably stabilized as a result of the moose reduction, and has been stable for 14 years (2003 -- 2017). By expanding their comparison across western Canada and the lower 48 states, they found that a separate herd subjected to another moose reduction was also stable, whereas at least 15 other herds not subjected to moose reductions are continuing to decline.
Dr. Ray's paper discuses and defines boreal caribou habitat restoration in the context of both national recovery efforts and insights from the rapidly advancing field of ecological restoration, and proposes criteria for what constitutes restored habitat. Currently, there is no consensus on the definition of “restored” habitat, despite a commitment by countries at the 2010 meeting of the Convention on Biological Diversity to restore 15% of degraded ecosystems by 2020.
Boreal caribou are a prime example of the difficulty of bringing back habitat that has been lost; decades are needed to restore mature forest habitats, and the extent of habitat loss that has already occurred adds a daunting dimension to the task. On top of these issues, conservation efforts are struggling against a legacy of inadequate attention to reclamation thus far.
An alternative to wolf control to save endangered caribou
Researchers study the effectiveness of a new government strategy to stabilize the caribou population by focusing on the reduction of invasive moose populations, indirectly lowering the density of the caribou's primary predator
What happens when invasive and native species are eaten by the same predator? If the invasive species is abundant, the native species can go extinct because predator numbers are propped up by the invading species. This process is called "apparent competition" because on the surface it "appears" that the invading and native prey directly compete with each other, but really the shared predator links the two prey.
Mountain caribou in British Columbia, Canada, observed during a population census.
Credit: Robert Serrouya CC BY 4.0
Apparent competition is an increasing problem, causing endangerment and extinction of native prey as abundant species colonize new areas in the wake of human-caused change to the environment. This is exactly what is happening to the iconic woodland caribou across North America. Prey like moose and white-tailed deer are expanding in numbers and range because of logging and climate change, which in turn increases predator numbers (e.g. wolves). With all these additional predators on the landscape, more caribou become by-catch, driving some herds to extinction.
Wolf Pack attacking a Moose
A short-term solution would be to kill wolves but this can be seen as just a band aid, and is no longer politically acceptable in many jurisdictions. As a more ultimate solution, Serrouya and colleagues used a new government policy and treated it as an experiment, to maximize learning. The new policy was to reduce moose numbers to levels that existed prior to widescale logging, with an adjacent reference area where moose were not reduced. The results of this research are published in an article titled "Experimental moose reduction lowers wolf density and stops decline of endangered caribou," and is published today in the peer reviewed and open access journal PeerJ.
Wolves will take the easier to kill Caribou over the tougher Moose
Following the reduction of moose using sport hunting, wolf number numbers declined, with wolf dispersal rates 2.5 × greater than the reference area, meaning that dispersal was the process leading to fewer wolves. Caribou annual survival increased from 0.78 to 0.88 for the Columbia North herd, located in the moose reduction area, but survival declined in the reference area (Wells Gray). The Columbia North herd probably stabilized as a result of the moose reduction, and has been stable for 14 years (2003 -- 2017). By expanding their comparison across western Canada and the lower 48 states, they found that a separate herd subjected to another moose reduction was also stable, whereas at least 15 other herds not subjected to moose reductions are continuing to decline.
he results obtained by Serrouya and colleagues are similar to other studies that used more controversial approaches. For example, in Alberta, 841 wolves were removed in the Little Smoky caribou herd over 7 years, but results were as good or better using the less controversial approach of reducing invasive prey (moose). But, population stability is insufficient to achieve recovery goals for caribou, which require population growth. This conclusion suggests that several limiting factors and management levers must be addressed simultaneously to achieve population growth for caribou. These levers include habitat protection, reducing invading prey, and if needed, short-term and focused predator removal.
.Journal Reference:
- Serrouya et al. Experimental moose reduction lowers wolf density and stops decline of endangered caribou.Peer J, 2017 DOI: 10.7717/peerj.3736
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Habitat Restoration and Protecting Caribou Populations
Habitat loss is – by far – the most common reason species become at risk of extinction. There are many ways to combat this threat, including protecting key areas from human activities, and restoring habitat that has been removed or otherwise damaged.
Protected Boreal Forest with thick horizontal and vertical tangle the key for Caribou health
Habitat restoration must play a large role in recovery efforts for boreal caribou. Many populations are declining where human activities like forest harvesting, agriculture, settlement, oil sands and roads have damaged or destroyed their habitat. Boreal caribou are currently listed as Threatened under the federal Species At Risk Act and under most provincial and territorial species at risk legislation where this animal resides.
A discussion paper on this topic by WCS Canada’s President, Justina Ray, was commissioned by Environment Canada as federal recovery efforts grapple with the challenge of habitat restoration. The paper was posted earlier this month onEnvironment Canada’s website:
Some type of balance of protected Boreal and that used
for energy must be put in place to keep Caribou alive and well
for energy must be put in place to keep Caribou alive and well
Boreal caribou are a prime example of the difficulty of bringing back habitat that has been lost; decades are needed to restore mature forest habitats, and the extent of habitat loss that has already occurred adds a daunting dimension to the task. On top of these issues, conservation efforts are struggling against a legacy of inadequate attention to reclamation thus far.
A key conclusion of the paper is that effective restoration for boreal caribou will require site-based restoration activities to be linked with range-scale land use planning and monitoring. It will be exceedingly difficult to recover boreal caribou populations once they are in decline and disturbance levels are high. Restoring ecosystems is typically a highly expensive process that requires substantially more effort than prevention of ecological damage in the first place.
To read the paper in its entirety: click here.
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