Northern Prairie Wildlife Research Center
Locating and Managing Peninsulas for Nesting Ducks
Location Factors for Peninsulas
Peninsula locations can be obtained by examining aerial photography or National
Wetlands Inventory data or by querying local resource managers. Aerial photographs
can be examined at county U.S. Department of Agriculture (USDA), Agriculture Stabilization
and Conservation Service (ASCS) offices or purchased from USDA-ASCS, P.O. Box
30010, Salt Lake City, UT 84130-0010. National Wetlands Inventory maps can be
obtained from the U.S. Geological Survey, Box 25046, Stop 504, DFC, Denver, CO
Aerial photographs of Alberta, Canada can be obtained at Maps Alberta, Land
Information Services Division, 2nd Floor, North Petroleum Plaza, 9945 - 108
Street, Edmonton, AB, Canada T5K 2G6. Aerial photographs of Manitoba and Saskatchewan
can be ordered from the Surveys and Mapping Branch, 1007 Century Street, Winnipeg,
MB, Canada R3H 0W4 and at the Map and Air Photo Distribution Center, 1st Floor,
2045 Broad Street, Regina, SK Canada S4P 3V7.
Shorelines of managed peninsulas should be free of tall emergent vegetation. Tall
emergent plants such as cattails and bulrush provide attractive foraging habitat
for raccoon and mink, but reduced habitat for loafing and feeding duck pairs.
Shorelines preferred by breeding pairs have bare soil or a covering of low grasses
and sedges. Alkaline wetlands usually produce the most suitable shorelines because
tall, emergent plants do not grow in alkaline soil. Wetlands with extensive blocks
of emergent cover such as cattails and bulrush should be avoided.
Peninsulas located at large, alkaline, semipermanent wetlands are the most suitable
for management. Alkaline wetlands that are preferred as construction sites are
classified as brackish, subsaline, and saline by Stewart and Kantrud (1971) or
mesosaline, polysaline, eusaline, and hypersaline by Cowardin et al. (1979). A
characteristic plant of alkaline wetlands is alkali bulrush, but these wetlands
often have few emergent plants. Alkaline wetlands probably provide superior conditions
for nesting ducks because these wetlands furnish poor food and cover for raccoon
and mink. Peninsulas located at large, fresh, semipermanent or permanent wetlands
with little emergent cover are secondary choices for management.
Peninsulas at seasonal or temporary wetlands should not be managed. These
wetlands are often dry and predator barriers may not function effectively in
most years. Also, peninsulas along the shorelines of large reservoirs generally
provide poor management sites because fluctuating water levels and severe wave
action regularly damage the predator barriers. Acceptable peninsula management
locations may, however, occur on small, stable reservoirs.
|Alkaline wetlands usually produce the most suitable
shorelines because tall, emergent plants do not grow in alkaline soil.
(photo by USFWS)
To be effective, peninsulas managed for nesting ducks should be located within
a good network of surrounding wetlands. At least 40 wetland basins or 80 wetland
acres (32 ha) should be located within 1 mile (1.6 km) of the managed peninsula
to supply food and cover for breeding pairs and broods. Mallards, gadwalls, and
northern pintails have large home ranges and will move 1 or 2 miles from wetlands
to nest on managed peninsulas. However, blue-winged teal have small home ranges
and will move one-half mile or less between wetlands and peninsulas to nest.
Wetland complexes with temporary, seasonal, and semipermanent wetlands supply
food and space for duck pairs in spring and for hens and their broods in summer.
Diverse wetland complexes are particularly important to ducks using peninsulas
at highly alkaline wetlands or permanent, fresh wetlands which may lack adequate
food and cover.
Maps showing the potential waterfowl breeding pair values for each 40 acre
unit of land are being created for eastern North Dakota and South Dakota and
northeastern Montana. The procedure uses Geographical Information System techniques
to combine data on wetlands, duck pair and wetland relationships, and breeding
duck home range for five upland nesting species. The maps are available at the
Habitat and Population Evaluation Team, 1500 East Capitol Drive, Bismarck, North
|To be successful, nesting peninsulas, like nesting islands,
must be close to good wetland complexes that support waterfowl breeding
pairs and broods. A good wetland complex would typically include 40 or
more basins within 1 mile of the peninsula. (photo by Northern Prairie
Wildlife Research Center)
Size and Spacing
Size and spacing are important considerations in peninsula management. It is usually
not cost-effective to construct predator barriers on peninsulas smaller than 3.5
acres. Small peninsulas generally attract few nesting hens, and they are nearly
as expensive to manage as large peninsulas.
Managed peninsulas should be spaced at least 1 mile from each other and from
other intensively managed nesting habitats. Separating intensively managed nesting
sites by a mile or more makes each accessible to different breeding pairs and
increases the chance of having more nests. However, intensively managed sites
should not be so widely separated that they cannot easily be visited and maintained.
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