No Easy Answers To The Plight of Mountain Caribou
Effective science relies on disagreement. Scientists challenge each other’s conclusions and require strong, reproducible outcomes before accepting results. Transparency is paramount, so researchers routinely make their data available for re-analysis. This study is a case in point. Two sets of researchers have come to vastly different conclusions about how to protect the mountain caribou.
Conservation of the caribou in Canada carries large economic, ecological, cultural, and social implications. Environment Canada considers woodland caribou threatened or endangered across the country. This study focuses on the four ecotypes of caribou found in western Canad: the boreal woodland caribou are non-migratory and live in forests from Newfoundland to British Columbia (B.C); the northern mountain caribou is found in northern B.C., the Yukon, and a small portion of Alaska; the Rocky Mountain crest is home to the central mountain caribou; finally, the southern mountain caribou occupies eastern B.C. — this ecotype is also known as the deep snow mountain caribou owing to the snow depths in its range.
The deep snow mountain caribou have experienced some of the most precipitous population declines. Caribou counts have dropped an estimated 45% over 27 years. Clear cut logging, habitat fragmentation, and road building all contributed to these losses. Logging opens up forests, drawing in other ungulates along with predators. This increases caribou predation and drives down their numbers. In response, government efforts have focused on predator control and protecting pregnant females through forced maternal penning.
But are these really the answer?
To assess the effectiveness of various adaptive management strategies, a group of scientists conducted a study of 18 caribou sub-populations in B.C. and Alberta. They concluded that using a combination of lethal wolf control and the maternal penning could limit population declines. However, the authors of this paper reject these conclusions, albeit with caveats. They reviewed the original research methods and re-analyzed the data. This examination revealed several issues.
While the original study included 18 sub-populations, there were in fact 42 populations for which data was available. Including these animals appears to alter the original conclusions about population trajectories. Also, not all adaptive management measures were considered. Neither the effects of closing sensitive areas to public recreation during calving, nor new government protections for the caribou, were looked at. And the effects of habitat alteration could not be replicated in the new study. After correcting for these issues, the re-analysis showed that wolf culling/maternal penning explained caribou population changes no better than habitat alteration or random chance alone. Indeed, ecotype is a better predictor of population trends than any adaptive management strategies considered in the original study. The four ecotypes respond to ecosystem disturbance in different ways. Thus, an approach that aids one ecotype may not help another.
While the answers aren’t clear, both people and the animals themselves all benefit from these vibrant discussions. Government officials, who used the original study to guide policy, should take this new research to account. Advocates can use this information to encourage policymakers to consider further actions aimed at protecting this iconic and threatened species.