Waterfowl Management Handbook

Complete Waterfowl Management Handbook

Thu, 31 Jan 2008 11:14:18 PST

The North American Waterfowl Management Plan, the Service's most recent mandate for management of migratory waterfowl, and recent legislation such as the Farm Bill all underscore the need for a single source of information about the management of waterfowl and their habitat. Much of this information exists in scientific papers, unpublished reports, or has never been recorded, and thus is not readily accessible by waterfowl managers. The need for a waterfowl management handbook was originally suggested to the Office of Information Transfer by personnel in the Service's north-central region. A prototype handbook was developed in 1987 and critiqued by 38 reviewers who provided suggestions on style and substance as well as topics for inclusion. The assistance of these reviewers, who included Federal and State wildlife managers, Federal and State biologists, and scientists in the United States and Canada, is most gratefully acknowledged.

This product differs from most Fish and Wildlife Leaflets. It will be issued as a series of chapters over the next several years, each with a unique number, designed to be inserted in an accompanying looseleaf binder. The Table of Contents will be issued when new information is added. Additional copies of leaflets will be printed for distribution to other resource professionals and private landowners. The four main subject categories are tabbed and color coded to allow easy reference and simple filing of future chapters.

13.1.15. Life History and Habitat Needs of the Black Brant

Dirk V. Derksen et al. — Thu, 31 Jan 2008 11:11:16 PST

The black brant is a sea goose that depends on coastal habitats from high arctic nesting sites in Canada, Alaska, and Russia to wintering areas in the Pacific coastal states, the Baja California peninsula, and mainland Mexico estuaries. Population estimates are based on aerial surveys in Mexico, California, Oregon, and Washington during mid-winter. Despite much annual variability in estimates, a plot of the counts from 1964 to 1992 reveals a significant downward trend in the winter populations (Fig. 1). Three of four major colonies on the Yukon&#;Kuskokwim (Y&#;K) delta declined an average of 60% during the first half of the 1980’s. This is significant because about 79% of the world population of the black brant nest in these colonies (Table). Because few other breeding colonies have been consistently monitored, we have little understanding of their dynamics.

Spring subsistence harvest in western Alaska coupled with fox predation on reduced Y&#;K delta populations, has limited the recovery of key nesting colonies. Degradation and loss of important staging and winter estuarine habitats from commercial and recreational development and disturbance are largely responsible for population reductions in British Columbia and the Pacific coastal states. In Mexico, industrial and recreational development in several estuaries may further limit winter habitats. Wildlife conservation agencies in Canada, Mexico, Russia, and the United States recently cooperated to examine population dynamics and factors that limit recovery of the black brant. This examination revealed important discoveries for management. This leaflet is a summary of these findings. More complete information on the life history of the black brant is in Bellrose (1980) and Palmer (1976).

13.1.11. Life History Traits and Habitat Needs of the Redhead

Christine Mitchell Custer — Thu, 31 Jan 2008 11:08:21 PST

Redheads are one of five common diving duck species in North America. They are in the same taxonomic group as the pochards or bay ducks and are most similar in appearance and behavior to the canvasback. Smaller body size, late breeding, wintering in southern areas, and tolerance to salt in winter and in breeding areas differentiate the redhead from the canvasback and suggest an evolutionary origin in the arid areas of the West. Parasitism of other waterfowl nests is more pronounced in redheads than in other North American waterfowl. These and other aspects of the biology of the redhead are the subject of this leaflet. Readers who are interested in general references on redheads are referred to Palmer (1976) or Bellrose (1980).

13.1.8. Life History and Management of the Blue-winged Teal

James H. Gammonley et al. — Thu, 31 Jan 2008 11:06:24 PST

The blue-winged teal is a small dabbling duck that is common in North America and northern South America. The species is highly mobile and has an opportunistic life history strategy. Breeding populations respond to variable wetland conditions in the drought-prone prairie regions of the north-central United States and southern Canada. Extensive habitat loss and degradation has occurred on the prairies and on neotropical wintering areas in recent decades. Renewed interest in the ecology and management of blue-winged teal has resulted from these environmental pressures. We review life history characteristics of blue-winged teal that are important to managers. Readers should consult Bennett (1938) and Bellrose (1980) for general references on the biology of blue-winged teal.

13.1.6. Life History and Habitat Needs of the Wood Duck

Katie M. Dugger et al. — Thu, 31 Jan 2008 11:02:16 PST

The wood duck is North America’s most widely distributed endemic species, and most of its wintering and breeding range falls within the 48 contiguous states (Fig. 1). The wood duck inhabits forested wetlands and, because of its need for nest cavities, is closely tied to North America’s remaining forest resources. Habitat destruction, market hunting, and liberal hunting seasons contributed to drastic declines and, in some cases, regional eradication of local wood duck populations. Subsequent implementation of hunting restrictions and the high reproductive rate of the species are responsible for the recovery of wood duck populations to current stable levels.

As prairie duck populations continue to decline, hunting pressure on the wood duck continues to increase. The wood duck is popular with hunters and consistently ranks high among species in Atlantic and Mississippi flyway duck harvests. Harvest pressure and continued degradation of riparian and lowland hardwood forests increases the need for a thorough understanding of wood duck population dynamics. Equally important to sustaining current wood duck population levels is an understanding of annual life cycle events and requirements.

13.1.3. Life History Strategies and Habitat Needs of the Northern Pintail

Leigh H. Fredrickson et al. — Thu, 31 Jan 2008 10:59:33 PST

The northern pintail (hereafter pintail) is a common dabbling duck distributed throughout the Northern Hemisphere. Since 1955, the breeding population in North America has averaged 5,566,000, fluctuating between 10,124,000 (1956) and 2,471,000 (1989; Fig. 1). Pintail numbers are especially sensitive to habitat conditions that reflect the wet–dry cycle in the shortgrass prairie breeding areas of south-central Canada and the northern Great Plains of the United States. Populations of pintails also are affected by habitat conditions in key wintering areas, such as the Central Valley of California and Gulf Coast marshes. When wintering areas are fairly dry, birds have fewer resources and subsequent spring recruitment is lowered.

Through the 1970’s, continental populations recovered when wetland conditions on breeding and wintering areas were good but fell when the prairies were dry and wetland conditions in wintering areas were poor. Unfortunately, habitat losses and degradation of prairie habitats caused by agricultural practices have coincided with prolonged drought since the early 1980’s. This combination of detrimental factors resulted in declining pintail numbers in the past decade. The long-term downward trend in pintail numbers has focused renewed attention on this species.

This leaflet describes aspects of pintail life history that may be important for pintail management. It is not intended as a general reference on pintail biology. Readers interested in this should consult Bellrose (1980).

13.1.2 Life History Traits and Management of the Gadwall

James K. Ringelman — Thu, 31 Jan 2008 10:56:32 PST

The gadwall is widely distributed throughout the western two-thirds of North America. Although its primary breeding habitat is in the drought-prone and degraded waterfowl habitats of the northern Great Plains, its continental population has remained relatively stable while those of most other dabbling ducks have declined. Some unique life history traits may in part be responsible for the resilience of gadwall populations. These unique attributes, which are important for gadwall management, are the subject of this leaflet. Readers interested in general references on gadwall biology and natural history are referred to Bellrose (1980) or Palmer (1976).

13.1.1. Nutritional Values of Waterfowl Foods

Leigh H. Fredrickson et al. — Thu, 31 Jan 2008 10:54:48 PST

Over 40 species of North American waterfowl use wetland habitats throughout their annual cycles. Survival, reproduction, and growth are dependent on the availability of foods that meet nutritional requirements for recurring biological events. These requirements occur among a wide variety of environmental conditions that also influence nutritional demands. Recent work on nesting waterfowl has identified the female’s general nutrient needs for egg laying and incubation. Far less is known about nutritional requirements for molt and other portions of the life cycle, particularly those during the non-breeding season. Although information on specific requirements for amino acids and micronutrients of wild birds is meager, the available information on waterfowl requirements can be used to develop waterfowl management strategies. For example, nutrient content of foods, nutritional requirements of waterfowl, and the cues waterfowl use in locating and selecting foods are all kinds of information that managers need to encourage use of habitats by feeding waterfowl. Waterfowl nutritional needs during the annual cycle and the nutritional values of natural foods and crops will be discussed below.

13.4.18. Chufa Biology and Management

James R. Kelley Jr. et al. — Thu, 31 Jan 2008 10:53:13 PST

Chufa (Cyperus esculentus) is an emergent perennial sedge that is common in seasonally flooded wetlands. Although chufa is common in many States, it is most abundant in the Southeast, including the Mississippi alluvial valley (Fig. 1). Belowground biomass of chufa, especially the tubers, serves as a valuable food source for waterfowl and cranes. Chufa tubers rank tenth among the most important waterfowl foods in the United States.

13.4.13. Management and Control of Cattails

Richard S. Sojda et al. — Thu, 31 Jan 2008 10:50:35 PST

The response of wetland vegetation to management can only be interpreted by considering an intricate mix of physiological, ecological, and temporal factors. Because cattail management is important for many freshwater marshes, the purpose of this leaflet is to present autecological principles for such management.

A 50:50 ratio of open water and vegetation is a frequent objective when managing cattail marshes in North America. When a particular marsh has been extensively flooded for some time and few cattails remain, managers may wish to foster more cattails to develop such hemi-marsh conditions. The reverse is followed when a marsh is dominated by cattails. Hemi-marsh conditions are optimal for breeding migratory birds, including most waterfowl, black and Forster’s terns, American coots, and yellow-headed blackbirds. During the nonbreeding season, the life history requirements of migratory birds are not as closely tied to the hemi-marsh conditions. However, such wetlands still provide excellent habitat.

Cattails are prolific and can quickly dominate a wetland plant community. Monotypic stands of cattails have reduced overall habitat value but do benefit some species of wildlife. They provide excellent habitat for wintering white-tailed deer and ring-necked pheasants and habitat for breeding marsh wrens, least bitterns, and various species of blackbirds. However, hemi-marshes also are habitat for these species, too.

Cattails also provide excellent roosting habitat for blackbirds that can severely damage adjacent crops, especially sunflowers in the prairie states. Elimination of the cattail stand removes roosting habitat and can reduce local damage, but the damage is often simply shifted to other areas where the displaced birds create new roosts.

Although the vegetation cycle in prairie marshes is based on the cycle of wet and dry years on the prairies, its basic principles apply to cattail management elsewhere. The cycle of a semipermanent marsh has four stages: dry, regenerating, degenerating, or lake marsh. Identifying the existing stage of a wetland is the first step toward determining the appropriate direction of subsequent management. Generally, all wetlands with cattails in their flora mimic aspects of this prairie marsh cycle. However, certain hydrologic conditions can lengthen the duration of any stage to such an extreme that no cycle is apparent.

13.4.12. Control of Phragmites or Common Reed

Diana H. Cross et al. — Thu, 31 Jan 2008 10:47:57 PST

Phragmites, or common reed, is a perennial grass often associated with wetlands. When phragmites is interspersed with open water or with other vegetation, waterbirds and small mammals find cover among the stems. Its dense root systems strengthen dikes and roads. On many sites, however, this robust emergent forms monotypic, impenetrable stands having little value for waterfowl. Ducks occasionally nest on the edges of large stands, but avoid the dense interior.

Phragmites is native to North America and is found worldwide, primarily in lowland temperate regions. Phragmites can occupy upland sites with seeps, or grow in brackish or fresh water several feet deep. Large monocultures are usually associated with impounded areas and resultant stabilized water regimes. Such sites, having levees or water-control structures that keep large areas moist for long periods, create ideal situations for phragmites to become a problem. The plants are less competitive when there is variation in water levels among wet and dry seasons and years. Growth is often stunted where soil fertility is extremely high or low or where salinity is high. Phragmites usually establishes itself on dry borders of marshes, but frequently invades shallow water foraging sites by out-competing and subsequently replacing more desirable emergent plants.

Because waterfowl benefit from interspersion of phragmites with other plant species and water, we do not recommend eradication of this plant from wetlands. Instead, phragmites should be controlled only to the degree necessary to achieve management objectives. By understanding the ecology and life history of phragmites, such control is more easily achieved.

13.4.11. Control of Purple Loosestrife

Daniel Q. Thompson — Wed, 30 Jan 2008 11:28:22 PST

Purple loosestrife is an herbaceous perennial weed that is native to Eurasia and probably arrived in eastern North America with early maritime traffic. The spread of this alien by 1900 (Fig. 1) was closely associated with canal and waterway traffic. By 1985 (Fig. 2), this aggressive weed had spread into all of the contiguous States north of the 35th parallel except Montana; similarly, all of the southern provinces of Canada had been invaded. In the last 20 years, loosestrife has become well established in reclamation projects and riparian wetlands in the West and Northwest. It has also invaded estuarine marshes in British Columbia.

The impact of this weed on North American wetland habitats has been disastrous. In many areas, purple loosestrife makes up more than 50% of the biomass of emergent vegetation. Moreover, these displacements are seemingly permanent, as seen in the Northeast, where many purple loosestrife stands have maintained themselves for more than 20 years. The effects of these changes have not been well studied but biologists believe that serious reductions in productivity of waterbirds and aquatic furbearers have resulted. Platformnesting species cannot use the stiff loosestrife stems for nest construction, nor are stems or rootstocks palatable to muskrats. In addition, dense, closely-spaced clumps do not provide brood cover or foraging areas. Although white-tailed deer and livestock will readily graze on young, succulent plants, palatability declines by late June and the forage value of wetland pastures that have been invaded by purple loosestrife is seriously reduced.

13.4.10. Control of Willow and Cottonwood Seedlings in Herbaceous Wetlands

Leigh H. Fredrickson et al. — Wed, 30 Jan 2008 11:25:59 PST

Willow and cottonwood are common species in forested wetlands and occur throughout most riparian and floodplain habitats of North America. These woody species are especially common in early successional stands where seasonal flooding occurs regularly. Cottonwood and willow are often considered problem plants, because they rapidly invade wetlands dominated by herbaceous flora and can form dense, extensive stands. The shade created by these species eliminates herbaceous undergrowth, and once the sapling stage is reached, cottonwoods and willows are difficult to eradicate. Control of these species can be costly and varies considerably with latitude.

13.4.9. Preliminary Considerations for Manipulating Vegetation

Leigh H. Fredrickson et al. — Wed, 30 Jan 2008 11:24:38 PST

A wide diversity of plants has adapted to the dynamic nature of wetlands. The continually changing floral landscape is shaped by physical or abiotic components that include climate, fire, soil, and water. Water quantity, quality, and chemistry have a dominating influence on wetlands as do factors such as hydroperiod (period when soils are saturated) and hydrological regime. Other factors that may affect the abundance, structure, and species composition of macrophytes or robust emergents are natural grazing, disease, and interspecific plant competition.

Vegetation is important to waterfowl for producing seeds, tubers, and browse; providing nest sites; and serving as substrates for animal foods. For example, the emergent marsh stage with the greatest number and diversity of birds has been called the “hemimarsh.” A maximum diversity and number of birds occur when vegetation cover and water interspersion in Type IV (semipermanent marsh) wetlands is at a 50:50 ratio. This wetland condition provides ideal nesting cover for waterbirds, as well as substrates and litter for invertebrate populations.

Emergent wetlands other than glacial marshes also require good interspersion of cover and water to attract waterfowl. Likewise, a diversity of wetland vegetation is much more desirable than a monoculture. As man expanded his activities in North America, the natural events producing mosaics of wetland vegetation were eliminated or altered. As an example, drainage or water diversion to enhance row crop production not only affects the immediate site, but often affects soil moisture conditions on adjacent areas as well.

This change in water availability influences plant species composition. Intensive cultivation for grains and forage, together with other human-related activities (water diversion projects, livestock grazing, and the elimination of natural fires) have modified the physical processes that influence the productivity of wetland systems. Managed areas throughout North America now must provide predictably good wetland habitat, despite modifications to water supplies, flooding regimes, and other physical factors.

Manipulation of wetland vegetation is a commonly employed tool. Although water-level manipulation is the traditional technique for modifying plant communities under intensively managed systems, other options include fire, grazing, and other physical and chemical disturbances. Values of vegetation structure and composition along with general concepts relating to manipulations are discussed.

13.4.8. Options for Water-level Control in Developed Wetlands

J. R. Kelley Jr. et al. — Wed, 30 Jan 2008 11:22:17 PST

Wetland habitats in the United States currently are lost at a rate of 260,000 acres /year (105,218 ha/year). Consequently, water birds concentrate in fewer and smaller areas. Such concentrations may deplete food supplies and influence behavior, physiology, and survival. Continued losses increase the importance of sound management of the remaining wetlands because water birds depend on them.

Human activities modified the natural hydrology of most remaining wetlands in the conterminous United States, and such hydrologic alterations frequently reduce wetland productivity. The restoration of original wetland functions and productivity often requires the development of water distribution and discharge systems to emulate natural hydrologic regimes. Construction of levees and correct placement of control structures and water-delivery and water-discharge systems are necessary to (1) create soil and water conditions for the germination of desirable plants, (2) control nuisance vegetation, (3) promote the production of invertebrates, and (4) make foods available for wildlife that depends on wetlands (Leaflets 13.2.1 and 13.4.6). This paper provides basic guidelines for the design of wetlands that benefit wildlife. If biological considerations are not incorporated into such designs, the capability of managing wetlands for water birds is reduced and costs often are greater.

Although we address the development of palustrine wetlands in migration and wintering areas, many of the discussed principles are applicable to the development of other wetland types and in other locations.

13.4.7. Managing Beaver to Benefit Waterfowl

James K. Ringelman — Wed, 30 Jan 2008 11:18:51 PST

Aside from humans, no other organism has the capacity to modify its environment as much as the beaver. In doing so, beaver create wetlands that provide valuable waterfowl habitats. Because beavers are widely distributed in North America (Fig. 1), beaver ponds can benefit waterfowl during breeding, migrating, and wintering periods. Mismanaged beaver populations, however, can severely degrade riparian habitats and become a costly problem. The key to successfully managing beaver for waterfowl benefits is understanding the values of beaver ponds in meeting the seasonal needs of waterfowl. Beaver populations must then be managed to provide these benefits in a self-sustaining manner compatible with the carrying capacity of the habitat.

Before the arrival of Europeans, 60–400 million beavers occupied 5.8 million square miles of North America. But by 1900, beavers had been so severely over-exploited by trappers and hunters that they were almost extinct. Today, beaver populations are on the upswing: 6 million to 12 million animals occupy diverse habitats ranging from the boreal forests of Canada south to the Texas gulf coast, and from California’s Central Valley east to the Atlantic seaboard. This recent population increase is a testament to the resiliency of beaver populations and their responsiveness to management techniques. I review some techniques useful for managing beaver populations and enhancing beaver habitats to benefit waterfowl, and explain the ecological relations and characteristics that make beaver ponds attractive waterfowl habitats.

13.4.6. Strategies for Water Level Manipulations in Moist-soil Systems

Leigh H. Fredrickson — Wed, 30 Jan 2008 11:15:24 PST

Water level manipulations are one of the most effective tools in wetland management, provided fluctuations are well-timed and controlled. Manipulations are most effective on sites with (1) a dependable water supply, (2) an elevation gradient that permits complete water coverage at desired depths over a majority of the site, and (3) the proper type of water control structures that enable water to be supplied, distributed, and discharged effectively at desired rates. The size and location of structures are important, but timing, speed, and duration of drawdowns and flooding also have important effects on plant composition, plant production, and avian use. When optimum conditions are not present, effective moist-soil management is still possible, but limitations must be recognized. Such situations present special problems and require particularly astute and timely water level manipulations. For example, sometimes complete drainage is not possible, yet water is usually available for fall flooding. In such situations, management can capitalize on evapo-transpiration during most growing seasons to promote the germination of valuable moist-soil plants.

13.4.5. A Technique for Estimating Seed Production of Common Moist-soil Plants

Murray Laubhan — Wed, 30 Jan 2008 11:14:06 PST

Seeds of native herbaceous vegetation adapted to germination in hydric soils (i.e., moist-soil plants) provide waterfowl with nutritional resources including essential amino acids, vitamins, and minerals that occur only in small amounts or are absent in other foods. These elements are essential for waterfowl to successfully complete aspects of the annual cycle such as molt and reproduction. Moist-soil vegetation also has the advantages of consistent production of foods across years with varying water availability, low management costs, high tolerance to diverse environmental conditions, and low deterioration rates of seeds after flooding.

The amount of seed produced differs among plant species and varies annually depending on environmental conditions and management practices. Further, many moist-soil impoundments contain diverse vegetation, and seed production by a particular plant species usually is not uniform across an entire unit. Consequently, estimating total seed production within an impoundment is extremely difficult.

The chemical composition of seeds also varies among plant species. For example, beggartick seeds contain high amounts of protein but only an intermediate amount of minerals. In contrast, barnyard grass is a good source of minerals but is low in protein. Because of these differences, it is necessary to know the amount of seed produced by each plant species if the nutritional resources provided in an impoundment are to be estimated.

The following technique for estimating seed production takes into account the variation resulting from different environmental conditions and management practices as well as differences in the amount of seed produced by various plant species. The technique was developed to provide resource managers with the ability to make quick and reliable estimates of seed production. Although on-site information must be collected, the amount of field time required is small (i.e., about 1 min per sample); sampling normally is accomplished on an area within a few days. Estimates of seed production derived with this technique are used, in combination with other available information, to determine the potential number of waterfowl use-days available and to evaluate the effects of various management strategies on a particular site.

13.4.4. Habitat Management for Molting Waterfowl

James K. Ringelman — Wed, 30 Jan 2008 11:10:20 PST

The ecology, behavior, and life history strategies of waterfowl are inseparably linked to that unique avian attribute, feathers. Waterfowl rely on flight capabilities to migrate, to fully exploit the resources of wetland and upland communities, and to escape life-threatening events. The insulation provided by contour and down feathers allows waterfowl to use a wide range of habitats and protects them from temperature extremes. Plumage is important not only for species recognition during courtship, but also for cryptic coloration of females during incubation. However, feathers become worn and must be periodically replaced. The process of feather renewal, or molt, is a critical event in the lives of birds. Despite the obvious importance of the molt, relatively little attention has been devoted to managing waterfowl during this period.

Unlike most birds, ducks, geese, and swans share the unusual trait of a complete, simultaneous wing molt that renders them flightless for 3 to 5 weeks during the post-breeding period. Concurrently, these waterfowl also renew their tail and body feathers. In addition to this post-breeding molt, ducks undergo a second yearly molt to renew all but their flight feathers. Here, I describe the nutrition, energetics, and management of molting adult ducks and geese, with emphasis on the period of molt when birds are flightless.

13.4.3. Managing Agricultural Foods for Waterfowl

James K. Ringelman — Wed, 30 Jan 2008 11:07:59 PST

Agriculture, more than any other human activity, has had a profound influence on North American waterfowl. Most agricultural effects have been detrimental, such as the conversion of grassland nesting cover to cropland, the widespread drainage of wetlands, and the use of pesticides that may poison waterfowl or their food. However, some by-products of agriculture have been beneficial, particularly grain or other foods left as residue after harvest. Many waterfowl are opportunistic feeders, and some species such as Canada geese (Branta canadensis), snow geese (Chen caerulescens), mallard (Anas platyrhynchos), northern pintails (A. acuta), and green-winged teal (A. crecca) have learned to capitalize on the abundant foods produced by agriculture. During the last century, migration routes and wintering areas have changed in response to these foods. Some species have developed such strong traditions to northern wintering areas that many populations are now dependent on agricultural foods for their winter survival.