Emma presented her opinion piece on whether wolf reintroductions are feasible conservation tools in the USA. Although controversial, reintroducing top predators like the wolf can facilitate widespread ecosystem change through trophic cascades and their position as a keystone species. She talked us through case studies where Mexican wolves (Canis lupus baileyi), Red wolves (Canis rufus) and Grey wolves (Canis lupus) have been reintroduced, and compared their long-term effects on the ecosystem and interactions with humans.
Grey wolves have been successfully reintroduced in the Northern Rocky Mountains (National Wildlife Federation https://www.nwf.org/Wildlife/Wildlife-Library/Mammals/Gray-Wolf.aspx)
The Red wolf had gone extinct in the wild, and only 11 reintroduced Mexican wolves remained, so their future depended on captive breeding and reintroductions. For a reintroduction to be successful the wolves must be able to establish self-sustaining populations; while the extinction of Mexican and Red wolves have been prevented, their populations may not be stable enough to persist. The Mexican wolves had reasonably well-preserved genetic diversity, but extensive livestock activity in the area has prevented them from expanding their range. A larger core protected area may be needed if the Mexican wolf population is to avoid extinction in the long run. The Red wolf population is under serious threat from hybridisation with coyotes, and their future also remains uncertain.1
The extinction of the Mexican wolf, left (Phil Degginger http://fineartamerica.com/featured/mexican-wolf–arizona-phil-degginger.html) and the Red wolf, right (Shattil & Rozinski http://www.arkive.org/red-wolf/canis-rufus/image-G112447.html) has been prevented through captive breeding and reintroductions.
On the other hand, the Grey wolf in the Northern Rocky Mountains has surpassed its target population size and should be able to persist without human intervention. Previously endangered across the States, the Grey wolf population is now stable with around 1600 individuals in the area. The elk populations have been reduced and their behaviour modified2, so that tree species like aspen and willow have been allowed to recover. This has again facilitated the recovery of species like bears and bison, and scavengers such as ravens which feed off the wolf kills. The recovery of willow and other tree species has created a niche for beavers, whose dams have changed the nature and biodiversity of the rivers.
With regards to the potential conflict with humans and livestock, compromise has been shown to be invaluable. The methods for dealing with conflicts, however, still need to be improved if future reintroductions are to be efficient and successful. In conclusion, the reintroduction of apex predators such as these wolf species is possible, but there is still plenty room for improvement in how this is achieved.
By Gyda Fenn-Moltu
1 Assessing the prevalence of hybridization between sympatric Canis species surrounding the red wolf (Canis rufus) recovery area in North Carolina. http://onlinelibrary.wiley.com/doi/10.1111/j.1365-294X.2011.05084.x/pdf
2 Foraging in the ‘landscape of fear’ and its implications for habitat use and diet quality of elk Cervus elaphus and bison Bison bison ttp://dx.doi.org/10.2981/0909-6396(2005)11[215:FITLOF]2.0.CO;2