Thursday, May 11, 2023

Managing Wildlife: Counting

Environmental & Science Education, STEM, Nature, Wildlife, Sustainability, Science & Society

Ed Hessler

--“The hope of the future lies not in curbing the influence of human occupancy – it is already too late for that – but in creating a better understanding of the extent of that influence and a new ethic for its governance.” --Aldo Leopold, Game Management, Charles Scribner's Sons, 1933; reissued in 1986, University of Wisconsin Press.

Way back, Dennis Anderson wrote about duck counts  (Outdoors, StarTribune, September 4). He began by noting that Aldo Leopold had once remarked on the difficulty of managing ducks and goes on to discuss that. I liked the essay because it is about a problem many scientists face: measurement.

Many of us know Leopold as the author of A Sand County Almanac , which is regarded as a landmark in the American conservation movement (See Wiki). It is not as well known that he was the author of the first book on game management and also chaired a new position in game management at the University of Wisconsin which was both a first for the University and the nation. Leopold is regarded as the proverbial father of the discipline of wildlife management. 

Both events, book publication and Leopold's appointment as chair occurred the same year: 1933. Game Management was reissued in 1986 (University of Wisconsin Press, originally published by Charles Scribner's Sons). Here is a review of the book from the scientific journal, The Auk (PDF 1988).

One way of thinking about ecology is as the distribution and abundance of the earth's plants and animals. In his essay, Mr. Anderson draws attention to the measuring the abundance of waterfowl. He begins by stating the management challenge but first comments on the distribution of ducks from the Arctic to South America, i.e., they are a shared resource among nations and states. This means that opinions about how best to manage them varies widely and waterfowl management becomes a diverse socio-cultural-political problemtoo.

Anderson cited the well known controversy between waterfowl managers from Louisiana and Minnesota, with southern managers complaining that Minnesota hunters "were killing too many ducks."  Minnesota waterfowl managers responded by complaining "that their southern counterparts abided too much illegal hunting, and as a result the number of ducks thought to be poached in the southern Mississippi Flyway rivaled the number killed legally."

In recent years, the issue has become "distrust" of population estimates with hunters complaining that there are fewer hunters because duck numbers are on decline "even though, as recently as 2015, the U. S. Fish and Wildlife Service (USFWS) reported North American ducks were at 'record high' population numbers." In that mix are two contentious issues, namely duck seasons and bag limits.The USFWS "regulations governing season lengths and bag limits" have been practiced for so long that they should be considered set in stone. Minnesota has 60-day seasons and six-duck daily limits.

There is another layer of controversy in Minnesota which in 2021 established "an early five-day 'experimental' teal season. These are the numbers from the first year: 50.000 blue-winged teal killed during the experimental season and "another 93,000 of the same species felled during the regular duck season." In 2020, the total bluewings killed was 93,000. Waterfowl researchers have justified both seasons: experimental and the federal hunting regulations." The claim which they believe is supported by evidence is "there's no harm in either."

Duck management is predicated on spring breeding counts and it is based "on the long-held assumption by duck surveyors flying over spring breeding grounds that the sighting of up to five drake mallards on a pond without a visible accompanying hen by definition meant that, nearby but unseen, was a hen mallard on her nest -- which surveyors counted as if they had season."

Anderson notes that this assumption is being challenged, buttressed by "estimates by an oldere but nevertheless respected way of counting ducks that uses banding and harvest data that seem to confirm that fewer -- perhaps far fewer -- hen mallards are on the breeding grounds."  This method "suggests mallards have been declining since 1999."

Until this question of abundance is resolved , Anderson makes these suggestions on what hunter should do which include make their best effort to "shoot drakes only, support Ducks Unlimited, Delta Waterfowl and similar groups."

You may wonder about the attention paid to mallard counts. They are, as Anderson points out, "critical to duck management."

The article "Duck Counts: Fact or Fiction" includes much more information.. The MN Department of Natural Resources (MNDNR) has published information on waterfowl management in Minnesota.

Finally, The idea of counting sounds simple: 1, 2, 3.... It isn't and includes many factors making it a complex problem to resolve and even then you can bet controversy about what the numbers mean will not go away.

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