Mallards are part of a group of waterfowl known as dabblers, named for the upside position of a feeding bird. These ducks prefer shallow ponds and marshes, feeding on greens and aquatic invertebrates. Mallards typically nest in a scrape on the ground near water and often near areas of heavy cover. They will use man-made structures such as nest boxes and occasionally hollowed logs. Nest boxes provide additional coverage and protection from weather and predators, especially when placed above ground.
Cut a piece of fencing wire about 2.10 metres (7 feet) long and 90 cm (36 inches) wide. This fencing will provide the base of the nest box. Plastic-coated fencing is recommended for its strength and rust protection.
Roll the first 90 cm (3 feet) of fencing wire into a cylinder, being sure that the opening remains 30 cm (12 inches) wide. Secure the cylinder in shape with plastic ties.
Place suitable covering material such as hay onto the remaining fencing wire. The material will provide camouflage and insulation for the nest box. A second set of hands will be helpful at this point to ensure the structure stays together and is rolled straight.
Continue rolling the fencing into a cylinder shape. Secure with plastic ties or cut wire after rechecking the size of the opening. If using wire, make sure sharp ends do not poke through the cylinder. Face fencing ends in versus pointing out from the nest. Using a pliers, turn in any uncovered sharp edges. Place some hay in the cylinder for a nesting base.
Determine the highest seasonal water level if placing the nest close to water. Seasonal flooding could wash out a nest box and make the ducks more vulnerable to predation. Once the height is known, place the cylinder on a platform no less than 90 cm (3 feet) above the highest seasonal level.
Find out what are the prevailing winds in the nest area. For added protection for the structure and its inhabitants, position the nest perpendicular to the wind direction.
Since mallard ducklings are precocial or independent after birth, make sure the nest is located in an area with adequate nearby cover such as a marsh to prevent predation as the ducks enter and leave the water. Be careful not to place the nest near raised areas, which can provide predators access to the nest.
Put the predator guard in place. The predator guard acts as a barrier, preventing predators from climbing or reaching into the nest. It is similar to a squirrel guard found on bird feeders.
Regularly monitor the condition of the nest. Replace hay as needed. Inspect the cylinder, platform and pole for any damage.
Keep your distance from an occupied nest. Mallards, like other birds, can be flighty when on the nest. Observe from a distance. Place the nest well before the nesting season has begun.
Make sure hay has been collected from an area that is pesticide-free.