By Tina Yerkes, Ph.D.
Upon arriving in the prairie pothole country in early spring, pintails find a cold and often frozen landscape. To pintails, the spring thaw can provide a virtual paradise of spring wetlands, or a dry, barren desert.
The Prairie Pothole Region is recognized as the duck factory of the world, and for good reason. Before European settlement, it was a vast and beautiful country dotted with more than 20 million acres of wetlands supporting unbelievable numbers of breeding ducks. Today, pothole country is still the most amazing place in the world for a waterfowl lover, but it has fewer wetlands than it once did, especially the shallow spring wetlands that pintails love.
Shallow spring wetlands, technically called ephemeral or temporary wetlands, are shallow depressions in the prairie landscape. Because they are shallow, they warm with the first hint of spring and melt before all others. They also trap melting snow and runoff. These wetlands are critical for attracting early-arriving ducks to settle in an area and are very important food sources. Duck pair densities are associated with the number of spring wetlands: More wetlands mean more duck pairs that settle in the area.
But not all spring wetlands are the same: Some are deep and will hold water throughout the year, while some are very shallow and will hold water for only a month or two. It is the shallow ephemeral and temporary wetlands that are the most important to pintails, and these are the first to be adversely affected by drought and farming practices (they are easier to drain and can often be cropped during dry years).
Pintails have a love-hate relationship with spring wetlands. Historically, pintail numbers tracked wetland numbers very well in the prairies. When the prairies were wet, in prime condition, and covered with spring wetlands, pintail numbers were high. But, when drier times occurred and fewer spring wetlands existed, pintail numbers were low. This pattern is due to the unique nature of pintails: Their numbers can boom when conditions are right. Pintails have several characteristics that set them apart from other ducks.
They have the ability to "get in and get out." That is, they are the first duck to arrive and nest in the spring; they lay fewer and smaller eggs, incubate for a shorter period, and have the shortest brood-rearing period. All this allows a hen pintail to produce ducklings in about nine weeks, compared to about 11 weeks needed by a mallard hen.
The best pintail years are those with the wettest springs. In these years, pintails can be found in great numbers on the prairies and experience good production. However, if the prairies are dry, they move on to greener (or wetter) pastures. This will result in fewer birds settling in the Prairie Pothole Region. Because pintails don't home as strongly as other ducks (see "Homeward Bound" in the March/April 2001 issue), they can respond to drought conditions by searching farther north.
When pintails are displaced farther north, it is generally believed that their production is reduced because fewer females attempt to nest. These females may travel as far as Alaska before attempting to nest, or they may not nest and choose to spend the summer on the tundra to simply survive and wait for a better year. By traveling great distances, pintails expend a lot of energy searching for suitable areas, and thus stored fat gained on the wintering and staging areas and normally used to lay eggs gets burned up.
Because of the unique nature of pintails, spring ponds are very important in attracting hens to settle and nest in an area, as well as providing a superb food source. Because these are the first open water areas, algae blossoms and invertebrates thrive in their soup of warm water. Some spring wetlands are located in farm fields, acting as deep-freeze storage bins by preserving waste grain for the first arrivals.
Pintails, as well as other ducks and shorebirds, enjoy the feast. Many shorebirds on the way to the Arctic find these spring wetlands irresistible and gorge themselves before completing the long journey north.
Unfortunately, under improved wetland conditions in the last decade, pintail numbers have failed to increase and track spring wetland numbers as they historically had. Something has gone wrong. One reason that pintails may not have responded to increased spring wetland numbers is that the composition of spring wetlands may have changed. Historically, many more of the ephemeral and seasonal wetlands that pintails depend upon were present in the spring.
Today, the spring pond count is higher, but the ponds counted may be composed of more permanent, deeper wetlands. Furthermore, many of the ephemeral and seasonal wetlands that do remain are often cropped in dry years and are surrounded by sparse vegetation. This has lead to increased siltation and contamination of these shallow wetlands. The end result is that even when they do contain water, they are far less productive for pintails than they were historically.
If spring wetlands are removed from the landscape, pintails have little incentive to settle an in area, even in wet years. If pintails are not attracted to settle in their traditional breeding areas, it is unlikely they will recover in the Prairie Pothole Region. Only conservation and restoration on a regional scale can affect ephemeral and temporary wetlands and the birds that depend upon them.
Conservation includes restoring wetlands as well as integrating waterfowl management with farming operations by working with farmers and ranchers who make a living from the land. Proactive wetland conservation programs must be developed for the long term, especially for the ephemeral and temporary wetlands that pintails depend on. We can have all the nesting cover in the world, but without wetlands, ducks won't settle to breed.