This chapter examines the potential role of the beaver in habitat restoration and other ecosystems services. As a tireless dam builder, the beaver can and should be an important ally in wetland restoration. For thousands of years, beavers have created and maintained wetlands that stored water and kept the water table high. Their leaky dams evened out the flow of streams. Leaky dams provide an ideal compromise of “ecosystems services.” First, they control flooding better than solid concrete dams because of their gradual release of water. Second, they slow down the flow suffiently to allow time for cleansing the water. This chapter first considers the impact of beaver dams on stream restoration before discussing how the beaver can contribute to wetland conservation and restoration.
This chapter explains how beavers select their food. Direct observation of the beavers' feeding behavior shows that they consume much nonwoody vegetation that leaves little trace. Aside from trees, beavers eat grasses and forbs on land and aquatic vegetation in the pond or at the lake bottom. Beavers are “central place foragers”: from the lodge where they live, they venture out in all directions to cut plants. They forage at greater distances upstream from their main lodge than downstream. This chapter discusses the range of plants eaten by beavers and where they harvest trees, their food choice and feeding behavior, seasonal changes of food preferences, food conditioning, food caches, and food processing. It also considers cafeteria-style food choice experiments that are conducted to test how beavers respond to food provided at their pond's edge.
This chapter focuses on beaver conservation and proactive management. Management of beaver populations is necessary. Where beavers are rare, reintroductions as well as the conservation of beavers and the restoration of their habitat are called for. Burgeoning beaver populations, on the other hand, require proactive management to prevent adverse consequences such as flooding and damage to trees. In either case, the main challenge is how to conserve functioning wetlands. This chapter discusses some of the important things to consider in beaver management, such as how large we should allow the beaver populations to be, or where we should permit beavers to settle and stay. It also describes the components of proactive beaver management, along with beaver behavior that we have to know for effective management. Finally, it emphasizes the importance of knowing the population genetics of beavers for management and conservation.
This chapter explains how beavers spend their time on a typical day. Three factors determine when a beaver is active and when it rests: exposure to the natural light cycle, air temperature, and season. Beavers stay in their lodge during the day, from about 0800 to 2000 hours in the summer in northern latitudes. During the first part of the night they feed, and during the second half they construct dams and lodges. The beaver can decouple its daily activity rhythm from the natural 24-hour light cycle. It shows a free-running activity period that is much longer than 24 hours. In summer, beavers are synchronized with the 24-hour day. In winter, above-ice activity ceases at certain critical low temperatures.
This chapter provides an overview of the beaver's diving reflex and thermoregulation, with particular emphasis on its evolution from a basic mammalian design into a superb amphibious, semiaquatic animal. It describes the anatomy of the beaver, which betrays the habit of extensive floating on the water surface: the vital air intake and sense organs are arranged so that the nostrils, eyes, and ears extend above the water while the rest of the head and body are submerged. It also explains how the beaver has acquired swimming and diving prowess without losing its ability to walk and even run, dig, and forage on land. Finally, it examines the beaver's thermoregulation in water and on land.
This chapter provides an overview of beaver mortality caused by predation. Without mortality at young stages, beaver populations would grow rapidly to enormous numbers. During the first six months of life, as many as 52 percent of the beaver population may perish. In the fist 2–3 years of life, mortality usually is highest, and between the ages of 5 and 9 years very few beavers die in unexploited populations. In most beaver populations the total mortality consists of two components: natural deaths from predators, accidents, disease, starvation, and so on; and deaths from trapping. This chapter looks at predators of beavers, including the wolf and coyote, beavers' antipredator behavior, and other causes of beaver mortality.
