Hunters should see a small increase in the number of ducks winging southward this autumn, but the migration will remain thin for several species, a sign that ducks remain troubled, our annual fall flight forecast reveals.

Ducks returning to the northern prairies this spring found a significant increase in the number of potholes, but this was not accompanied by a sharp increase in numbers of breeders for several key species.

The failure of some key duck populations to rise sharply despite improved prairie pothole breeding conditions, coupled with declining juvenile productivity, are the reasons for our predicted mediocre fall flight.

A look back over the past decade shows:

Figure 1. The number of potholes on the northern prairies this spring totaled nearly 5.4 million, a 37 percent increase over the previous year. The potholes count represents average water conditions. Source: USFWS

As you can see, the number of potholes found on the breeding grounds was the fourth highest total reported in the past decade. Traditionally, an increase in potholes produces an increase in the number of breeding ducks.

The following graph shows the total numbers of ducks (in millions) found in the traditional North American survey area over the past decade. The survey includes the traditional species – mallards, pintails, gadwalls, shovelers, widgeon, blue-wing teal, green-wing teal, canvasbacks, redheads and scaup – plus a smattering of black ducks, ring-necked ducks, goldeneyes, buffleheads and ruddy ducks.

Figure 2. The total number of ducks counted this spring on the North American breeding grounds totaled 31.7 million, a one percent decline from the preceding year and the second lowest total of the past decade. Source: USFWS

The total number of ducks this spring fell one percent from the preceding year despite a significant increase in the number of potholes.

One of the most worrisome declines involved mallards, our most abundant species and the most common duck in the hunter’s bag. Mallards are very opportunistic, quickly taking advantage of improved breeding conditions. But this spring the mallard breeding population declined nine percent despite a 37 percent increase in the number of potholes.

Our fall-flight forecast, based on a somewhat complex equation involving numbers of breeding ducks, pothole counts, adult summer mortality, historic productivity rates and juvenile gunning vulnerability, is shown in the following graph that compares forecasts over the past decade.

Figure 3. Our fall flight forecast calls for a small increase in the number of ducks that will migrate southward this autumn when compared to last year.

The data predicts this autumn’s fall flight will be 21 percent larger than last year. Unfortunately, most of the increase involves only three species – early migrating blue-winged teal, pintails (one allowed in the bag per day) and lowly shovelers. These three species accounted for 94 percent of our projected increase.

The mallard fall flight is expected to decline by one percent. The gadwall, widgeon, green-winged teal flight and scaup flights will be similar to last year.

Thus, hunters who focus on blue-wings and shovelers may find significantly improved hunting. The remainder of us can look forward only to a slightly better season than last year.

Finally, there is this ominous note. The U.S. Fish and Wildlife Service predicts the mallard and pintail breeding populations will decline further next spring.