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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.

Photo of quick-kill body trap box. Figure 4: Diagram of quick-kill body trap box.
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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