June 11, 2009

Reindeer Numbers Falling Across Northern Hemisphere

Reindeer and caribou populations are declining around the world, from Alaska and Canada, to Greenland, Scandinavia and Russia.

The iconic deer is incredibly important to indigenous groups in the north. However, it is growing trickier for the deer to live in a world growing hotter from climate change and changed by industrial development.

Reindeer and caribou all belong to the same species, Rangier tarandus.

Caribou live in Canada, Alaska and Greenland, while reindeer live in Russia, Norway, Sweden and Finland.

Although there are seven species of the animal, each group is genetically and behaviorally diverse, even though they can breed with one another.

Each subgroup is also affected in different ways. For instance, the Canadian populations of caribou have declined from logging, oil and gas exploration, and road construction, says Liv Vors from the University of Alberta in Canada. On the other hand, reports began coming in that the populations of other herds were also decreasing.

"When we discovered that many herds of reindeer also were declining we decided to compile a comprehensive survey to see if this indeed was a global pattern," says Vors.

Vors and Mark Boyce at the University of Alberta got in touch with other researchers around the globe and researched published reports and government statistics for all the data they could find about reindeer and caribou populations. They stockpiled information on 58 major herds in the Northern Hemisphere.

The scientists were stunned to find that 34 of the herds were falling, while no information was available for 16 others. Only eight herds saw an increase in population. A few herd's numbers had been falling at least a decade.

"We were surprised at the ubiquity of the decline," says Vors. "We knew that woodland caribou in North America were in bad shape."

The researchers were, however, surprised that caribou and reindeer numbers seem to be almost synched across the Northern Hemisphere.

"When we delved into the status of European reindeer herds, we were surprised that so many were declining. We expected them to be in better shape than North America herds because reindeer, namely the semi-domestic herds, are closely managed by humans."

The populations were plotted on a map by the researchers, which is available in Global Change Biology.

"Seeing that sea of red was a sobering moment," Vors said to BBC News. "If global climate change and industrial development continue at the current pace, caribou and reindeer populations will continue to decline in abundance."

"Currently, climate change is most important for Arctic caribou and reindeer, while anthropogenic landscape change is most important for non-migratory woodland caribou."

The climate change means much warmer summers, which causes more insect activity, and caribou and reindeer that are bothered by bugs cannot feed as well to put on weight prior to winter. Springs that arrive earlier mean plants are dying when the migrating animals reach them, while the freezing rains of the warmer winters create ice on the ground. The caribou and reindeer get to their food, and then starve.

"In time, however, climate change will become more important for woodland caribou, and landscape change will have a greater effect on arctic caribou and reindeer," Vors continues.

"There likely will be more forest fires in woodland caribou habitat, as well as diseases and parasites transmitted to caribou from white-tailed deer, whose range is expanding northward in Canada. More roads are being built in the Arctic, as well as infrastructures like diamond mines, and these sometimes interfere with migration routes."

Unless something is done soon, all seven sub-species will eventually die off.

"The concern is that their habitat and the climate are changing too quickly for them to adapt," Vors added. "From a Canadian perspective, the caribou is part of our national identity. Canada's caribou migrations have frequently been identified as one of this country's natural wonders, and the species even appears on our 25-cent coin."


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