Wednesday, November 22, 2017

How Many Ducks?

How many ducks did we used to have in the United States?

Well, that depends on what you are using as your base number.  Ducks Unlimited reports a pretty optimistic number for pre-Columbian times:

To estimate how big the fall flight might once have been, we can use modern-day duck populations and work backward. Let's assume that there are 50 million breeding ducks (total ducks, not pairs) distributed across the United States and Canada. It's been a very wet spring and 33 million of these ducks have settled on the prairies, while another 17 million can be found in Alaska, the western boreal forest of Canada, and areas outside the TSA. Given such conditions, we may have a fall flight of 100 million ducks, which we will use as our benchmark for modern day duck populations when the prairies are wet.

Now turn the clock back to 1805, when Clark was trying to get some sleep along the Columbia River. Assuming that the prairies have also been very wet, we have 100 million total breeding ducks (including both paired and unpaired birds) on the prairies. Duck numbers outside the prairies are unchanged at 17 million. This means that 200 years ago, we had 117 million breeding ducks compared to 50 million today (or 2.3 times as many ducks). At face value, this translates into a fall flight of about 230 million birds (2.3 x 100 million).

But we haven't yet accounted for changes in recruitment. Let's assume that recruitment on the prairies was twice what it is today, mostly due to higher nest success and duckling survival. Not only have we tripled the number of ducks on the prairies; they're twice as successful at producing young. We'll spare you the math, but this pushes our presettlement fall flight estimate to around 430 million birds, even if we assume that duck breeding populations and recruitment outside the prairies have not changed.

Of course, we used to have a lot FEWER ducks in the U.S.

By the 1930s, ducks, geese and swan numbers were down to about 50% of what we have today, and conservation cartoonist Ding Darling was predicting they might be gone in a decade or two unless things changed.

Darling worked to make things change, initiating the Federal Duck Stamp program in 1934 and designing the first stamp to help fund the refuge system and acquire more wetlands. President Franklin Delano Roosevelt subsequently appointed Darling head of the U.S. Biological Survey, the forerunner of today's U.S. Fish and Wildlife Service, and Darling helped found the National Wildlife Federation in 1936. That same year President Roosevelt convened the first North American Wildlife Conference administered by the American Wildlife Institute (now the Wildlife Management Institute).
1930 cartoon from Ding Darling.

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