Waterfowl Identification Guide Comprehensive Conservation Plan Phone: 218-8474431 |
Waterfowl
The prairie pothole region has historically been recognized as the most important waterfowl production area in North America. Surveys have shown that although this area represents only 10 percent of the breeding habitat, it averages 50 to 75 percent of the duck recruitment each year in North America.
Numerous waterfowl species use the prairie wetlands of Minnesota. Some of these species include: Redhead, Northern Shoveler, Blue-winged Teal, Mallard, Gadwall, Wood Duck, Canvasback, Canada Goose, Pintail, Lesser Scaup, and Ring-necked Duck. Prairie wetlands are critically important for breeding, feeding, and migration habitats for these species.
The Habitat and Population Evaluation Team (HAPET) Office survey waterfowl populations within the Wetland Management Districts of western Minnesota. Summary statistics generated by HAPET provide a necessary overview of waterfowl production and land use in the Districts. Their results show the variability between districts in breeding pair density. The average duck pair density ranges from 23.5 in the Fergus Falls WMD to 3.7 in the Windom WMD (Figure 1).
Rich soils and prairie wetlands make the region ideal for waterfowl, but also highly productive for agriculture. The corn and soybean belt overlaps extensively with the southern prairie pothole region. Massive conversion of wetlands and prairie to agricultural fields has dramatically altered the landscape, the hydrology, and the region's carrying capacity for waterfowl.
Some waterfowl species are more susceptible than others to the transformation of prairie into agriculture. Mallards and Blue-winged Teal have been fairly successful in agricultural landscapes such as western Minnesota. Northern Pintails, on the other hand, have declined more dramatically than any other waterfowl species in North America (Ducks Unlimited 1990). At the turn of the century, Pintails were probably as common in the prairies as mallards (Roberts 1932). Pintails favor ephemeral ponds, which were the first and easiest to drain. They often nest far from water and ducklings have to move overland to get to ponds shortly after they hatch. In the current landscape, newly hatched ducklings cross plowed agricultural fields in the spring and they are vulnerable to predation. Like Pintails, Gadwalls were once very common in this region. In 1879, Gadwalls were reported to be as abundant as Mallards if not more so (Roberts 1932, in Galatowitsch and van der Valk 1994). Now, Gadwalls comprise less than 1 percent of the breeding population in western Minnesota (Green and Janssen 1975). Roberts (1930) reported, the gadwall "...suffered most severely from the settling of the country, probably as much from breaking-up of the prairie, where it commonly nested, as from the hunters." (Galatowitsch and van der Valk, 1994). At the turn of the century, Canvasback and Redheads were common on the largest lakes and marshes. Initially, over-hunting depleted Canvasback populations but the decline of wetland habitat, especially the wild celery beds, made it difficult for them to recover (Galatowitsch and van der Valk 1994). Another diving duck, the Scaup, was also common but is now primarily a migrant through the region.
Figure 1: Estimated Average Duck Pair Density, 1987-1999
Research has shown that ducks nesting in large blocks of grassland habitat (1,000 to 10,000 acres) reproduce more successfully than ducks nesting in smaller blocks (200 to 500 acres) (Burger et al. 1994; Ball et al. 1995). Ron Reynolds of the HAPET Office in North Dakota found waterfowl production increased on WPAs near large blocks of CRP land (personal communication). His results show the importance of working with partners to increase effective habitat block size and offset habitat fragmentation.
A major factor depressing duck numbers is low nest success due to nest destruction by predators on small units of habitat. Predators are quick to find these remnant areas and concentrate their hunting activities on the vulnerable ground nests of waterfowl. In some habitats, predators such as red fox, raccoon, mink, and skunk are able to take virtually every duck nest and many of the attendant hens.
Although agriculture has been an important feature in this area for over 100 years, it has been particularly intensive during the last several decades. Conversion from small, diverse family farms to large agricultural operations specializing in monocultures of small grain and row crops has eliminated habitat on private lands such as pasture, hayland, and wetlands. Grassland birds are forced to nest in ever-dwindling fragments of remaining cover. Often the only nesting sites available are small isolated areas such as roadside ditches, abandoned farmsteads, rock piles, or isolated patches of habitat such as our Waterfowl Production Areas (WPAs).
The average block size for Waterfowl Production Areas in western Minnesota is only 210 acres. In part, the small size of most acquisitions is due to the nature of the Small Wetlands Acquisition Program (SWAP). The original SWAP approach was simple — purchase only a minimum of acres in fee-title and surround them with permanent easements.
In truth, it is difficult to purchase large tracts of land in prime agricultural areas. What research identifies as an optimal size for wildlife is not always possible given the competing needs for the land. Local county land boards often will not support taking large blocks of land out of agricultural production and off the tax role. Areas that are important for waterfowl may not be available or for sale. To purchase land strategically, managers are faced with the difficult task of finding willing sellers in the most productive areas for waterfowl.
The landscape level monitoring by the HAPET Office shows that waterfowl success varies depending on location within the state. There is even great variance between WPAs within a single District. The HAPET Office has produced a map for each district that ranks locations for waterfowl production. The maps are known as "thunderstorm maps" because they resemble doppler radar weather maps (Figure 2).
Existing GIS mapping data can be used to evaluate land acquisitions. Available information can be compiled to pick land parcels that have high potential for waterfowl and that are located near other conservation lands, such as state, county, or CRP set-aside land to increase the "effective size" of each unit. This approach can aid in setting priorities of acquisition. Ideally, managers could use these maps to identify "hot spots" within their district for purchase as WPAs.
Figure 2: Predicted Settling Density of Dabbling Duck Pairs
The Districts are trying to combat the unnatural impact of predators in small pieces of habitat by removing abandoned buildings and brush. Abandoned farmsteads are prime denning sites for major nest predators such as skunks (Lariviere and Messier 1998a, 1998b; Lariviere et al.1999). In addition, the Districts place nesting platforms in many wetlands, and predator control is practiced on a limited scale in conjunction with electric fence exclosures on 350 acres in Fergus Falls and 10 acres in the Morris Wetland Management Districts.
Another threat to waterfowl reproduction is the increasing application of agricultural chemicals such as fertilizers, insecticides, and herbicides on cropland adjacent to WPAs. Research has identified agricultural chemicals as important factors in decreasing bird populations directly as well as affecting their food resources in wetlands.
Not all species of waterfowl are in decline. In recent years, the population of Giant Canada Geese has exploded across many of the Districts. Many WPAs contain the large wetlands favored by geese. These wetlands are often adjacent to private agricultural land. Canada Geese are upland grazers and, like most wildlife, will take advantage of the bounty planted nearby, whether it be succulent sprouts of soybeans, corn, or the grass of lawns and golf courses. On certain areas, geese can cause considerable financial hardship for farmers by wiping out relatively large areas of crops.
Although the more common species of ducks and geese in Minnesota have increased over the last decade, many are still below the goals of the North American Plan.
Migratory Birds
Minnesota Wetland Management Districts contain habitat important to bird species other than waterfowl, including songbirds, marsh and wading birds, shorebirds, raptors, and upland game birds. Approximately 243 species of birds regularly use the Districts at some time during the year, with 152 nesting species.
The U.S. Fish and Wildlife Service and the Minnesota Department of Natural Resources, Partners in Flight, an international bird conservation initiative, and others have evaluated the status of migratory birds, identifying "species of concern" at the state, regional, and national levels. Partners in Flight have developed a bird conservation plan that focuses on declining grassland and wetland birds in the Northern Tallgrass Prairie Bird Conservation Region. This plan provides information on the habitat needs of these species and proposes a model of landscape-level habitat conservation for grassland birds (Fitzgerald et al. 1998). In the Districts, 48 birds identified as "species of concern" are rare, declining, or dependent on vulnerable habitats, including 43 that breed there. This list does not include hunted waterfowl or federally-listed threatened or endangered species.
About 44 percent of the species of concern depend on some type of grassland habitat. Important habitats in the District include native and restored prairies, seeded grasslands (cool- or warm-season grasses), light- to moderately-grazed pastures, Conservation Reserve Program lands (CRP), sedge meadows, old fields, and hayfields (if not mowed before July 15). In North America, grassland birds have exhibited steeper declines than any other avian group. Their decline has a number of causes: loss of breeding and wintering habitat from agriculture, urbanization, habitat degradation from fire suppression, inappropriate grazing regimes, woody plantings, pesticides, and nest predation and Cowbird parasitism.
Within the category of "grassland birds," individual species show a variety of habitat preferences based on vegetation height, cover density, grass/forb ratio, soil moisture, litter depth, degree of woody vegetation, and plant species composition. It is important to maintain a mosaic of grassland habitats to meet the varying needs of grassland birds.
Some of the species of concern found in the Districts are area-sensitive, which means they require large, contiguous blocks of habitat to reproduce successfully. Area-sensitive species include the Greater Prairie-chicken, Northern Harrier, Upland Sandpiper, Bobolink, Henslow's Sparrow, and Savannah Sparrow.
Vertebrate and Invertebrate Species of Concern
"Species of concern" refers to those species for which the Service has incomplete and inconclusive information, but which might be declining in range, numbers, or security. Service and state agency biologists and other experts confer on and use natural heritage data bases and other published and unpublished information to follow the welfare of these species. They have no protection under the Endangered Species Act (Act) and are not candidates for listing.
Species of concern are a diverse group of animals united by two factors: (1) the Service is watching them, and (2) they occur within the general area and thus could appear in or near tracts within the Districts. Some of these animals occur only in prairie habitats. Some of the arthropods can live only in good tallgrass prairie habitat and thus are good indicators of high quality prairies. It is not possible to predict which, if any, of the species may occur on tracts within the Districts, nor predict how their occurrence would be a factor in decisions regarding individual tracts. They are necessary components of a healthy, functioning tallgrass prairie ecosystem and are indicators of prairie tract quality.
Region 3 of the U.S. Fish & Wildlife Service has developed a Resource Conservation Priorities (RCP) document that includes all species of concern within the Region (U.S. Fish and Wildlife Service 2002). The Minnesota Department of Natural Resources maintains an official state list of animals being watched for changes in abundance and distribution, and of animals that are endangered or threatened and protected by state law. The Service will consider species listed by the State of Minnesota along with Service species of concern in evaluating prairie sites and developing site protection measures.
Reptiles, Amphibians, and Insects, Vertebrates and Invertebrates
Reptiles, amphibians, and insects may have limited popular appeal, but each species plays an important role in the prairie ecosystem. The degree of interconnectedness in the tallgrass prairie ecosystem is high. Landmark species such as the eagle, badger and coyote find their food sources in these groups. Prairie plant diversity depends upon pollination and seed dispersal, as well as soil aeration by the great variety of insects. Grasshoppers (family Orthoptera) are major herbivores in the prairie ecosystem, and many native prairie flowers rely on bees, butterflies, and others for pollination. Numerous prairie birds, amphibians, reptiles, and small mammals feed exclusively or partly on insects. The web of successes and failures within tallgrass prairie communities is anchored to every point of diversity within the system, and the protection of this entire spectrum is necessary for the persistence of its varied parts.
Listed Endangered and Threatened Vertebrates and Invertebrates
This section describes animals that are Federally listed under the Endangered Species Act of 1973, as amended, and are listed as either endangered or threatened.
Threatened Mammals
Gray wolf, Canis lupus: Experts estimate approximately 2,000 gray wolves presently occur in Minnesota. Wolf numbers and range appear to be increasing in Minnesota. Wolves are no longer exclusive residents of Minnesota's forested wilderness areas, and adult wolves from Minnesota have dispersed through central and western Minnesota to North and South Dakota. The Service recognizes the improving range and security of the species and in early 2003 reclassified the wolf from endangered to threatened.
Threatened/Endangered Birds
Bald Eagle, Haliaeetus leucocephalus: Bald Eagles have increased in abundance and distribution across the United States, including Minnesota, and have been reclassified from endangered to threatened. In the 1990s nesting territories increased in Minnesota every year from 437 in 1990 to 618 in 1995. Increasing numbers of migrating and wintering eagles also occur across Minnesota where they find sheltered night roosts and feed on waterfowl, smaller wild mammals, and fish in open water areas. Bald Eagles became endangered because of habitat loss, but especially because of DDT use following World War II. Today, the DDT threat is largely gone. Now the challenge is to prevent contamination and loss of sites that eagles depend on for nesting, feeding, migration, and wintering.
Piping Plover, Chadarius melodus: Piping Plovers are tenuously present in Minnesota. They nest in Lake of the Woods, east of the Districts. Piping Plovers nest in coastal areas, but they are also prairie birds, nesting across the Great Plains of the United States and Canada, but in perilously low numbers. The Great Plains population is listed as threatened. The loss of prairie wetland areas contributes to their decline. Like many shorebirds, Piping Plovers feed on immature and adult insects and other invertebrates at the water's edge. They winter primarily along beaches, sandflats, and algal flats on the Gulf of Mexico.
Least Tern (eastern population), Sterna antillarum: Listed as endangered, the Least Tern nests along large rivers of the Colorado, Red, Mississippi, and Missouri River systems. This species is a potential nester in the Missouri River area. It nests on sand and gravel bars and protected beach areas of large rivers and winters in coastal Central and South America. The species is endangered because human disturbance and alteration of river systems has rendered much of its nesting habitat unusable. Pesticides may reduce food available to the tern by reducing the numbers of small fish in their feeding areas.
Reintroductions
The public has an interest in seeing presettlement native wildlife species returned to the landscape. Examples include Greater Prairie Chickens, Trumpeter Swans, bison, and wolves. Giant Canada Geese, once thought extinct, have returned to the prairies of Minnesota in numbers as a result of captive breeding and reintroduction programs. However, at times restoration efforts, and the ensuing adaptability of the species like the Canada Goose, can create its own set of management problems.
Due to the relatively small size of WPAs and the concerns for impacts off of WPAs, reintroductions of species like bison and wolves are not practical. However, Trumpeter Swan reintroductions have been successful and well-received by the public, while Prairie Chicken reintroduction is showing some sign of success depending on the area. There is also the potential for reintroducing species of prairie plants and native small mammals, reptiles, and amphibians and even insects like the Dakota Skipper butterfly on certain units.
Management of Resident Species
Federal trust species are generally those that cross state and international boundaries or are afforded national protection through various laws and treaties, such as the Migratory Bird Treaty Act and the Endangered Species Act. The well-being of waterfowl populations is a classic Federal trust responsibility and the main purpose for the creation of the Small Wetland Acquisition Program in the 1960s. This does not mean that resident species such as white-tailed deer and pheasants found on WPAs should not receive management attention. Rather it is the degree of management focus, based on the knowledge that management for trust resources like waterfowl will usually benefit the myriad of resident wildlife that share the prairie-wetland landscape.
Local and regional residents, however, may often favor the management for those species like white-tailed deer and pheasant that provide consumptive recreation opportunities. Thus, managers are often faced with requests for food plots, tree and shrub plantings, or direct stockings of game species that may have a negative effect on the primary purpose of waterfowl production and the broader goals of restoring native plant communities. The key is to seek the proper balance between practices focused on trust species and those that can accommodate the public's desire for resident wildlife management.
Note: The above information is an excerpt taken from the Detroit Lakes WMD Comprehensive Conservation Plan (CCP). The above cited references and other useful information can be found by reviewing the full plan at the following link: Detroit Lakes CCP.
