Because only female ducks will actually use a nest cavity, a female Wood Duck, a female Hooded Merganser, and female Common Goldeneye are illustrated (photos by Paul Konrad).

Some ducks require cavities to nest in, most notably Wood Ducks, and the lack of natural tree cavities that are large enough for a female Wood Duck to nest in has created an important conservation effort to provide big nest boxes across this beautiful ducks’ North American range. But there are a number of other cavity nesting ducks that also benefit from the availability of big nest boxes, including Hooded Mergansers, Common Goldeneyes, and Buffleheads, along with Common Mergansers and Barrow’s Goldeneyes, – that’s 6 species in North America!

Each of these cavity nesting species of ducks has their own life history and distribution characteristics, so if you are interested in attracting a certain species, learn about it individually. However, from the standpoint of selecting or building a nest box, 3 of the 6 species of cavity nesting ducks can use the same size of nest box – Wood Ducks, Hooded Mergansers, and Common Goldeneyes.

But there is one small difference for Common Goldeneyes – a ¼ inch difference in the size of the entrance hole. The preferred entrance hole diameter for Common Goldeneyes is ¼ inch higher and wider than the entrance sizes for Wood Ducks and Hooded Mergansers, so if you are interested in specifically trying to attract nesting Common Goldeneyes, make the entrance a ¼ inch higher and wider – or if you buy a Wood Duck nest box, enlarge the entrance hole that much larger to accommodate a female Common Goldeneye.

Common Mergansers are larger ducks that require a larger nest box and a much larger entrance hole, while Buffleheads are smaller ducks that need a smaller nest box with a 3 inch entrance hole. The nest box size for Barrow’s Goldeneyes falls between these 2 species, so be specific when providing nest boxes for these ducks.

A list of nest box dimensions is provided below for your review, and to get more information about the individual preferences for each species, including a nest box construction plan, the elevation range where the nest box should be installed, the proximity to water, the preferred habitat of each species, nesting range maps, and other important “Helpful Tips,” be sure to refer to the species-specific NestWatch link provided below.

Wood Duck entrance hole: 3 inches high and 4 inches wide; nest box size 9x9x24 high; see NestWatch | Wood Duck - NestWatch

Hooded Merganser – same as Wood Ducks, entrance hole: 3 inches high and 4 inches wide; nest box size 9x9x24 high; but refer to NestWatch | Hooded Merganser - NestWatch

Common Goldeneye entrance hole: 3¼ inches high and 4¼ inches wide; nest box size 9x9x24 high; see NestWatch | Common Goldeneye - NestWatch

Bufflehead entrance hole: 3 inches in diameter; nest box size 10x12x14 high; refer to NestWatch | Bufflehead - NestWatch

Common Merganser entrance hole: 5 inches high and 6 inches wide; nest box size = 11x11x24 high; see NestWatch | Common Merganser - NestWatch

Barrow’s Goldeneye entrance hole: 4 inches high and 5 inches wide; nest box size = 9x9x24 high; refer to NestWatch | Barrow's Goldeneye - NestWatch

For the best information about all the potential birds that might use a big nest box, along with the sizes of nest boxes and entrance holes for each species, habitat and installation information, along with predator proofing info, please consult the Cornell Lab of Ornithology’s NestWatch where you will find several web pages that will serve you and inspire you; see NestWatch | All About Birdhouses - NestWatch

“Features of a Good Bird House” also provides a wealth of excellent information about nest boxes at NestWatch | Features of a Good Birdhouse - NestWatch

Give it a try by installing one big nest box – and see if you can limit your interest to just one.

When providing artificial cavities – nest boxes – you are helping cavity nesting birds during the most important part of their life cycle, the nesting season, which is a most honorable conservation activity! Please also keep in mind that providing a nest box for ducks is fun, as well as fulfilling, and sometimes exhilarating. Take pride in your efforts to help benefit some of our most popular birds and enjoy the upcoming nesting season!

You can purchase a Duck Nest Box at Heartwood Joy Box Wood Duck House at BestNest.com and Audubon Wood Duck House at BestNest.com and Woodlink Wood Duck House at BestNest.com but be sure that any nest boxes you are considering have a side panel that opens for you to monitor nesting activities and clean the nest box after each nesting attempt.

Share your backyard birding experiences and photographs with The Birding Wire at editorstbw2@gmail.com