Northern Prairie Wildlife Research Center
Locating and Managing Peninsulas for Nesting Ducks
Management of Peninsulas
The manipulation of nesting cover and control of mammalian predators are important
considerations at peninsulas managed for nesting ducks. The primary duck species
nesting on peninsulas prefer tall grass and forb (1-to 2-feet) and low shrub (less
than 4 feet) cover. Hens generally avoid tall shrubs (more than 4 feet high) and
trees for nesting. Peninsulas lacking adequate nesting cover can be improved by
rejuvenating or protecting existing vegetation or by seeding new plants.
Seeding Grass-Legume Nesting Cover
Good nesting cover can be provided at peninsulas by seeding proper mixtures of
tall, introduced grasses and legumes. Grass-legume mixtures should be seeded into
a firm soil substrate. Prior to seeding, existing plants at the site should be
eliminated by repeated cultivations or use of wide-spectrum herbicides. Grass-legume
seedings are best completed using small grain drills or no-till drills. Seeding
should be completed in early spring, late fall after plant growth has stopped,
or winter after peninsula construction. Suitable grass-legume nesting cover includes
intermediate wheatgrass, tall wheatgrass, and smooth brome mixed with alfalfa
and small amounts of sweetclover. Introduced grass and legume seeds are widely
available at seed dealers distributed throughout the western United States and
Canada (Appendix B). For detailed advice regarding grass-legume
seedings, refer to Duebbert et al. (1981).
The vigor and attractiveness of planted grass-legume cover vary between years
but tends to decline over time. Plant vigor can be restored for several years
by cultivating existing stands. Prior to the cultivation treatments, remove
the existing plants using fire or mowing. Cultivation should completely disturb
the soil and plant roots to a depth of 4 to 6 inches. The treatment should be
conducted in spring or late fall. Revegetation will occur naturally on the cultivated
area from roots or dormant seeds in the soil.
Removing Tall Shrubs and Trees
Tall shrubs such as northern hawthorn and wild plum, and trees such as box elder
are generally avoided by nesting ducks because the foliage shades out low ground
cover. Tall shrubs and trees also provide perching and nesting sites for avian
predators. Tall shrubs and trees should be removed from managed peninsulas by
cutting and then spraying ensuing sprouts with an approved herbicide.
Branches and wood debris that remain after shrubs and trees have been cut
down should be stacked in piles and burned. However, fire should not be allowed
to extend throughout the peninsula. Burning is not recommended for peninsulas
as fire will temporarily eliminate all nesting cover and permanently reduce
the important forb and low shrub cover component. Burning is advised only at
peninsulas that are to be reseeded or to eliminate piles of dead shrubs and
trees.
Livestock and Fencing
Nesting cover that has been reduced on peninsulas by grazing can be restored by
excluding livestock. The electric fence or moat will help exclude cattle but additional
fencing may be required. Fall or perhaps winter grazing may be of most concern
because cattle can reach peninsulas by crossing through wetlands when they are
shallow, dry, or frozen. Fall grazing is detrimental because vegetation that provides
nesting cover for the next year is removed. Additional fencing or a change in
the grazing practices may be required in these situations. Electric fences should
remain energized when livestock are present to prevent damage to the wire mesh
and posts by rubbing.
Managing Predators
Mammalian predators that gain access to managed peninsulas should be removed by
trapping. It is extremely important to employ a skilled trapper who is able to
effectively remove all species of mammalian predators. Trapping can be accomplished
by using snares, live-traps, quick-kill body traps set in boxes (Figure 4) or,
if necessary, leg-hold traps. Trapping should extend from early April, when wetlands
become ice-free, until mid-July, when nesting is essentially completed.
Generally, traps should be set only on the managed peninsula and not on the
adjacent mainland or shoreline. Traps set on adjacent lands will capture many
animals that are not destroying nests on the managed peninsula. Traps should
be dispersed throughout the peninsula habitats. Productive trapping sites include
shorelines, rock piles, dens, and patches of tall, emergent plants.
Avian predators have not been a primary concern on managed peninsulas in North
and South Dakota and Montana. However, in some areas, American crows and black-billed
magpies may take duck eggs and large raptors may kill nesting hens. Avian predation
may be reduced by removing tall shrubs and trees from the managed peninsulas
and the adjacent shoreline.
| Figure 4. Illustration of a quick-kill
body trap set in a box. The rear of the box is closed by 1/2-inch wire
mesh to prevent access but allows the animal to see inside. Dimensions
of the box are 24" × 12" × 12". |
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Barriers
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U.S. Department of the Interior |
U.S. Geological Survey