Backyard ponds in Britain often feature floating duck houses. Commercially available floating duck houses are usually decorative, octagonal pagodas. Conservation workers prefer a design known as a "hen house" that has proven effective for mallard duck breeding. A hen house is a tube of wire mesh lined with hay and attached to a post in shallow water. It provides mallards a safe place to nest, away from such predators as ferrets, pine martins and foxes. A decorative floating duck house with a hen house feature suits a growing mallard family.
Saw the 5 by 15 cm (2 by 6 inches) boards into eight boards, 1.2 m (4 feet) long, using a circular saw.
Saw the 20 cm (8 inch) diameter cedar pole into three 1.2 m (4 foot) sections.
Lay the three poles on the ground parallel to each other and 30 cm (12 inches) apart.
Nail the boards on top of the poles using 7 cm (3 inch) galvanised nails. Space the boards 1.2 cm (1/2 inch) apart. This will create a platform approximately 1.2 m (4 feet) square.
Cut the wire mesh into two pieces with wire snips to create one 1 m (3 foot) and one 1.2 m (4 foot) length of mesh.
Roll the smaller piece of wire mesh to form a cylinder with a diameter of 28 to 30 cm (11 to 12 inches). This is the inside surface of the hen house.
Tie the cylinder in place using four 5 cm (2 inch) strips of stainless steel wire.
Spread a 5 cm (2 inch) deep layer of flax straw on the remaining 1.2 m (4 feet) of wire mesh.
Roll the straw-covered mesh around the cylinder, trapping the straw between the layers.
Tie the outer cylinder with four strips of stainless steel wire. You should have a straw-filled roll 1 m (3 feet) long and 28 to 30 cm (11 to 12 inches) in diameter.
Cut two pieces of two-by-four, 1 m (3 feet) long. These will form the support beams for the hen house tube.
Nail the two-by-four support beams flat to the platform, parallel to each other 10 cm (4 inches) apart across the centre of the platform, forming a cradle.
Hammer four 7.5 cm (3 inch) galvanised nails halfway into support beams, one at each end, forming mounting nails for the hen house tube.
Place the tube onto the support beam cradle, between the mounting nails. The tube should be suspended slightly above the surface of the platform so water will not enter it.
Tie the tube to the mounting nails with 10 cm (2 inch) strips of stainless steel wire.
Cut two pieces of 1.2 cm (1/2 inch) plywood, each 1 by 1 m (3 by 3 feet).
Nail the plywood together in a tent shape over the nest tube. This optional step forms a roof for additional weather protection.
Cut a piece of 1.2 cm (1/2 inch) plywood, 15 by 45 cm (6 by 18 inches). This will form an entry ramp from the water.
Nail the entry ramp to the entrance of tube house with galvanised nails into the support beams. Angle the ramp down into the water.
Fill the tube house with soft grass up to 2/3 full for nesting material. Do not block the entrance.
Anchor the duck house with a chain and a weight in 1 to 1.2 m (3 to 4 feet) of water at least 1.2 m (4 feet) away from shore.
Alternatively, use cedar or redwood planks, which will be more durable than untreated lumber. If your platform is not floating high enough out of the water to keep the hen house dry, place layers of rigid foam insulation sheets underneath. Replace the flax straw each year as hens may pull it out for their nest. Male mallards are called "drakes" and females are called "hens," hence the name "hen house."
Use untreated plywood. Pressure-treated plywood contains chemicals like arsenic that are poisonous for wildlife. Don't make your tube wider than 30 cm (12 inches) in diameter. Otherwise, Canada geese may nest in it.