In early spring, weeks before biologists take wing to conduct aerial surveys of the North American breeding grounds, the most avid among us pick up the telephone to call acquaintances and field biologists who live on the northern prairies. We want to know whether potholes are abundant or scarce. This is important because potholes are viewed as a predictor of the fall flight. The accepted biological rule is that great numbers of potholes translate into greater juvenile productivity and increased numbers of young in the autumn migration. Dry conditions produce the opposite.

This year we received grim news. Drought gripped the prairies in its iron talons, our informants related. Potholes were few and widely scattered. This suggested the fall flight would be very thin.

Of course, these early reports often are geographically limited and represent personal observations – the sort of evidence waterfowl biologists often dismiss as “anecdotal.” We knew we would have to wait until the breeding-ground survey was completed and the U.S. Fish and Wildlife Service issued its official tally, a precise number.

This month the service announced its pothole count – 4.4 million. This represented a disappointing 37 percent decline from the previous year. But this was not horrific news, as you can see in the following graph.   

The data reveals this spring’s 4.4 million pothole count falls comfortably within the average range. Why, then, if we had average water conditions, did cries of doom continue after completion of the breeding-ground survey?

Delta Waterfowl rued “dry conditions across the prairie breeding grounds,” a situation especially acute on key production areas which Delta’s chief waterfowl biologist Frank Rohwer depicted as “dry…real dry…bad dry.”

Ducks Unlimited’s chief biologist Dale Humburg lamented that “severe drought occurred across much of the north-central U.S. and Prairie Canada,” a condition described as “painful.”

Even the U.S. Fish and Wildlife Service’s Nathan L. Zimpfer, lead author of “Trends in Duck Breeding Populations,” leaped on the bandwagon. Although he noted this year’s count was only 10 percent below the long-term average, he still wailed about “drought in many parts of the traditional survey area.”

What, pray tell, is going on? How can an average number of potholes constitute a drought? Have these biologists been struck dumb?

The issue goes to the heart of waterfowl biology – and the service’s increasing reliance on raw survey numbers to promulgate hunting regulations and preserve our breeding stocks.

The nub of the problem is the breeding-ground survey. Is it accurate?

We can assume biologists flew the same transects and counted potholes in the same manner as previously. Thus, we can conclude the survey is statistically accurate. But this is largely academic because the survey assumes all potholes are biologically equal, which we know is not the case.

For example, with the advent of the U.S. Conservation Reserve Program in the mid-1980s, thousands of formerly tilled acres were converted to grassland, surrounding potholes with abundant nesting cover. The Eastern Dakotas became a major mallard breeding ground. The production of young soared.

This year survey biologists counted 845,000 potholes in the Eastern Dakotas. This is only 11 percent below the long-term average. Yet, in previous years when pothole counts were lower, we heard no hue and cry about drought. Why?

The reason is that this year precipitation was uneven. The eastern portion of the Eastern Dakotas had higher than normal numbers of potholes. But in this area there is very little nesting cover. Juvenile production is minimal. In the western portion of this region, the areas that are the big duck producers – the Drift Prairie and the Coteau – were virtually dry. Thus, duck production from the Eastern Dakotas this year is expected to be severely curtailed.

A similar situation exists on some high-production areas on the Canadian prairies, prompting knowledgeable biologists to declare that juvenile production and the fall flight will be far smaller this year than the pothole count would indicate.

The pothole count is therefore highly suspect, a sometimes unreliable and flawed measure of actual nesting conditions. If biology has learned anything from CRP, it is that potholes surrounded by expanses of grassland are far more biologically valuable than potholes found amid a sea of wheat, corn or soybeans. This higher valuation is not accounted for in the continental survey that only measures total numbers. This can render year-to-year comparisons meaningless.

Clearly, we need a total pothole count, but we also need a mathematical analysis that reflects the overall biological value of our potholes. It would take into account surrounding habitat conditions, attractiveness to breeding ducks and so on. The point value of a biological pothole analysis would have greater meaning than the raw total. It would allow us to make meaningful year-to-year comparisons of nesting habitat conditions and more accurately predict the fall flight.

All of this might be moot if we allowed mature judgment to guide the setting of our hunting regulations. But we do not. The Adaptive Harvest model turns a deaf ear to biological Paul Reveres who this year have sounded the alarm. Adaptive Harvest proponents will simply plug into their nonpredictive population model the total pothole count. Barring some unforeseen change, this will cause the model to call for another liberal season. The result can be predicted. Few young ducks this autumn will fly south, causing the sport hen kill to fall heaviest on adults that are most likely to successfully hatch a clutch of eggs and fledge a brood. These hens represent the most valuable component of our migrant flocks, the ducks we want to preserve for breeding stock, the ducks we want to protect from over-gunning.

All of this tells us the closely linked survey and regulations-setting process is fatally flawed. It is not an example of scientific rigor. Instead, it is a portrait of the U.S. Fish and Wildlife Service’s biological and managerial incompetence.