Canadian government officials noted a significant decrease in the caribou population of this region between 1942 and 1955.

Apparently, the pipeline makes them frisky, too: In twenty years, the caribou population has skyrocketed, from 3,000 to almost 27,100.

Both effects are expected to cause a fall in caribou populations because females produce fewer calves if less food is available.

There is a very small Peary caribou population as well.

People remained in the valley until the mid-19th century, when the caribou population declined and people moved closer to the coast.

The Peary caribou population has dropped from above 40,000 in 1961 to about 700 in 2009.

When caribou populations declined around 1900 and again in the 1920s, many Nunamiut moved to the coastal villages.

Many caribou populations behave in an intermediate manner between these two extremes.

Overall, Alaska's caribou population was relatively low in the mid 1970's, numbering around 250,000 statewide.

But at the same time, the caribou population was expanding.