Understanding Waterfowl: Beaver Ponds and Breeding Ducks

Growing beaver populations have created an abundance of high-quality habitat for waterfowl

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Photo © Marshall Haferkamp

By Bruce Batt, Ph.D.

"We have mined the northland, not for wheat, not for gold-but for fur. Now the fur seed is gone."

Those words were spoken in 1938 by Ducks Unlimited Canada's first general manager, Tom Main. He was relating his ideas about how to resolve the challenges facing waterfowl as DU began its first year of operation. Main and many others believed that beaver ponds were an integral component of the original habitat that once produced sky-darkening flocks of waterfowl. By the time DU started its conservation work, however, nearly all the beavers and the millions of ponds they had created along the continent's rivers and streams were gone.

Main wanted to focus the bulk of DU's early work on re-establishing populations of fur-bearing animals, especially beavers and muskrats, in Canada's Boreal Forest. He selected basins to be restored by engineers so breeding stock could be reintroduced and protected until their numbers could sustain a harvest. He believed that reestablished beaver populations would eventually restore many of the ponds that had existed when the first Europeans arrived to exploit the region's seemingly limitless fur resources. In short, he envisioned the beaver as a primary partner in the quest to restore North America's waterfowl populations.

Main thought that the Canadian prairies were in good hands with the Prairie Farm Rehabilitation Administration. This Canadian federal government agency was dedicated to restoring prairie water resources to support agricultural and urban development following the devastating drought of the 1930s. Main believed that waterfowl and other wildlife would also be beneficiaries of the agency's projects.

DU did not pursue Main's plan because the logistics and expense of working in the Boreal wilderness were well beyond the capabilities of the young organization. A year later, the start of World War II placed tremendous demands on resources and manpower, further limiting DU's early efforts. There were also plenty of important and more cost-effective things to do for waterfowl on the prairies, which remain the primary focus of DU's work even today. Only in recent decades has DU started to tackle issues affecting wetlands and waterfowl in the Boreal Forest.

As the modern conservation ethic evolved in the United States and Canada during the 20th century, every province and most states embraced the restoration of fur resources. Beavers were always a priority because of their historically high market value. Trapping was limited, breeding stock was transplanted, and regulations were established and enforced. These efforts resulted in one of the greatest conservation accomplishments of the past century. Beavers are now firmly reestablished throughout their former range. In fact, beavers have become a nuisance in settled areas where their dam-building activities flood forests, farmland, and roads. There are now an estimated 12 to 15 million beavers across this continent, still far fewer than the 60 to 100 million that are thought to have been here 200 years ago.

Research has verified that beaver ponds provide important habitat for waterfowl. In a large study conducted by DU in the Clay Belt region of Ontario, the most abundant breeding duck in beaver pond-rich forests was the mallard. Other common breeding ducks on beaver ponds include cavity-nesting wood ducks, hooded mergansers, buffleheads, and common goldeneyes. Beaver ponds also provide breeding habitat for American black ducks, blue- and green-winged teal, American wigeon, and ring-necked ducks.

DU's Ontario research also recorded almost 10 pairs of breeding waterfowl per square mile of forest. DU had hoped to further increase waterfowl numbers and productivity in this area by implementing a variety of management techniques, but the research did not support the economics of directly managing beaver ponds for waterfowl. For this reason, more indirect methods have been implemented, such as working with trapping organizations and the forestry industry while supporting helpful public policies. Densities of beaver ponds across much of the Boreal Forest are not as high as they are in the Clay Belt, which has above-average numbers of beavers. However, the Boreal Forest is 2.3 million square miles in size, and beavers are found on almost every suitable stream where they can settle and establish colonies.

In Atlantic Canada, much of DU's initial work involved restoring wetland basins that had gone dry when beavers were extirpated during the early 20th century. As beaver populations recovered over the past few decades, they created problems for wetland managers by plugging water-control structures, which had to be cleared by hand. In recent years, DU has stepped back and let the beavers manage many of those basins on their own, allowing our conservation staff to direct their efforts elsewhere.

Beaver populations have also expanded across the United States. In many areas, especially in the West, beavers are increasingly viewed as key partners in the restoration of diverse plant and animal communities. Beaver ponds provide vital habitat for many species of fish, amphibians, and birds while also conserving threatened water supplies and moderating downstream flooding.

But what effect do beavers have on continental waterfowl populations? DU and others have long chronicled and fought the loss of wetlands important to waterfowl. Despite all our efforts, the net loss of wetlands has continued and even accelerated on the continent's most important waterfowl breeding, migration, and wintering areas.

As natural wetlands have declined, man-made water bodies such as reservoirs, storm-water retention basins, borrow pits, and golf course ponds have increased on the landscape. Many man-made ponds and lakes are of limited value to waterfowl, although they do serve some wetland functions. DU and its conservation partners restore, enhance, and protect high-quality natural wetlands that provide crucial habitat for waterfowl and other wildlife. As nature's wetland engineers, beavers are in the same business, and they do all the work themselves. They just get on with it, without permits, contracts, or regulations, and at no cost except in areas where they become nuisances.

Over the past 20 years, populations of many waterfowl species have reached historically high levels, and we have enjoyed liberal hunting regulations as a result. This occurred despite the continued net loss of natural wetlands on the breeding grounds. How has this been possible? For one thing there are once again several million beaver ponds across the continent, with the largest number of these habitats found in northern areas where the majority of waterfowl breed.

Most biologists would agree that over the past two decades we have had favorable water conditions on average across the prairies and in other important waterfowl breeding areas, which has allowed the birds to have good reproductive success. Waterfowl have also adapted positively to some of today's farming practices. DU and others certainly have done great work in many areas, but I believe that another key factor has been the quiet recovery of beaver populations, which continue to grow and to restore productive wetlands across their range. Beavers truly are a partner in wetlands restoration and maintenance, just as Tom Main had hoped they would be over 75 years ago.

Dr. Bruce Batt served as Ducks Unlimited's chief biologist before retiring in 2007. He currently divides his time between his residence in Memphis, Tennessee, and a cabin on Lake of the Woods in Canada.