On the Refuge

Counting wildlife may seem simple, but it can be one of the more difficult things that wildlife managers do. Simply counting what you see can be misleading, as animals can be missed, important areas can be inaccessible, and visibility can vary among vegetation types. You could make assumptions and test them, but in the case of Columbian White-tailed deer, we have turned to technology to get around these problems.

Columbian white-tailed deer are counted using infrared videography-a video camera that sees heat. Mammals are usually hot compared to their surroundings and they show up as white silhouettes against a gray background. By taking to the air and flying a slow methodical grid, one can count just about every deer in an area and differentiate deer from cattle, sheep, goats, and elk.

This year's count showed that Puget Island is at a 10-year high of 227 animals, 26 deer per square mile. The Julia Butler Hansen Refuge's Mainland unit is at 75. 26 deer per square mile plus 13 more on Hunting/Price Islands for a total of 88. This means that prior to the removal of deer during the levee crisis, the Mainland Unit alone had 109 deer, 38 deer per square mile, in 2013. Those levels are expected to return in the next year or two. Tenasillahe Island had 154 deer, 56 deer per square mile.

While historically lower in density, Puget Island has been a stable population over the years. But why does it seem like more deer are there when there are fewer per square mile? This is due mainly to visibility and habituation to humans. Pastures on Puget normally have shorter grass and less cover, and deer there are more comfortable lingering in the open. Puget also has more roads and more access. Deer are harder to see on the Refuge, but that doesn't mean they're scarcer, only that it's easier to hide.