Assistant Professor - Natural Resource and Ecology Management
Extension Wildlife Specialist
Iowa State University Extension and Outreach
As I write this, in the waning days of February, many of the wildlife that grace Iowa’s cities and farms during the spring and summer, are far away. Some are gone in a physical sense, like the wood duck who in October was still toiling on Iowa wetlands but today is gorging itself on Mississippi or Louisiana acorns. Others are gone in a psychological sense, like the hibernating little brown bat, retreated deep in a cave or abandoned mine somewhere in a southern Iowa hillside. Although I fancy myself a lover of winter, I must say that I reflect on the status of these species with some envy, as I wrap up what seems like the 100th pass over my side walk with shovel in hand this winter and brace myself for icy bouts across campus.
Nevertheless, I’m thankful for the few species that stick it out with us and brighten our wintery days, like the welcome squealing of a black-capped chickadee I hear at my bird feeders or the sight of a northern kestrel overseeing its domain from a power line along a gravel road. It won’t be long before all these species, and many more, grace us once again full-time in their annual return or reemergence on Iowa’s landscapes for the season of backyard barbeques, swimming, and of course, for the animals, raising young.
Imagining the warmth of those days, and their impending arrival is a welcome distraction here in the final days of winter. Another welcome distraction is the opportunity to attend to a characteristic all these species share: their affinity for the industrious capabilities of cabin-fever stricken humans.
Indeed, now is the time to get to work in warm workshops creating habitat features from wood that can attract these species and many more for our enjoyment and their use in their annual summer rituals. Here, I explore two primary types of woodworking for wildlife projects that you may find appealing as you wait for the robin’s return, and one last one, creating places for you and your family to enjoy the fruits of your labor.
The image that “woodworking for wildlife” conjures for most is probably one of a “bird house” with four sides, a sloping roof, and small hole on the front. This is certainly the basic entry point for woodworking for wildlife, an activity sure to satisfy many of our wild neighbors. Many different shapes, sizes, and designs are available for ‘bird houses’. What each design has in common is its targeting of a category of birds that biologists refer to as “secondary cavity nesters” a designation that distinguishes most hole-seeking birds from the woodpeckers, who can make their own holes (and thus are known as “primary cavity nesters”). Secondary cavity users look for holes in many different places, including those abandoned by woodpeckers or holes created by the natural decay of scars from broken branches on trees.
Among the wide diversity of these so-called secondary cavity nesters, biologists have noted a strong affinity for certain holes sizes for certain species of birds: an inch and an eighth for chickadees and wrens, and an inch and three eights for the white-breasted nuthatch and so on. Deviations from these sizes make boxes more or less attractive to target species and a difference of only a quarter-inch can be the difference between a successful box and yard ornament!
Boxes for secondary cavity nesters come in all shapes and sizes to target dozens of species in Iowa. Most familiar are the smaller boxes that target for example eastern blue-birds or house wrens. These species are common and in many cases can be found in and around city houses and farmsteads throughout the state. A well-designed box targeting wrens or blue-birds could also become a home for black-capped chickadees, white-breasted nuthatches, or even a southern flying squirrel in heavily wooded areas of southern and eastern Iowa. Step up the box and hole size and you can attract larger cavity nesters, like the eastern screech owl or American kestrel. One more step up and you have a box that’s attractive to one of Iowa’s most common and beautiful breeding ducks, the wood duck. Wood ducks and another cavity nester, the hooded merganser, annually fly over river-side forests and neighbors with mature trees in search of a 4” x 3” oval hole within a mile of a water source to raise their young in. Lucky observers may even see ducklings plunge from the boxes in the day after their birth, on their way to water to eat and grow.
Roosts and other structures
The next category of woodworking projects for wildlife falls under a broad umbrella of roosts, platforms, or other structures animals other than cavity nesters use. There seem to be no limits to the creative capacity of nature lovers, so one can find design specifications for structures for anything from a turtle to an osprey. The projects most applicable for most Iowa home or acreage owners are platforms for robins or shelters for bats and bees.
Robins are not too picky in where they choose to place their nest – any relatively flat, elevated surface seems to suffice. That’s why this simple design has been developed to attract a nesting pair.
In a sharp contrast, bats are considerably pickier in where they choose to spend their summer days. The natural place for some of Iowa’s 9 species of bats to spend their days includes the small spaces between flakes of bark and certain tree species, cavities or crevices in dead or living trees, or even the rafters of barns or other accessible areas of buildings. All these spaces share the same common feature: tight spaces in warm environments. Some mothers will raise their young in these spaces while the males of other species will spend their summer days there until the fall breeding season arrives. It is these spaces that bat houses try to mimic. Given their picky affinity for the shape, size, and temperatures of their roosts, many different designs of bat houses have been developed and design specifications are quite prescriptive for appropriate sizes, ventilation, and board-spacing. The design at this link complies with those prescriptions and is a good challenge for intermediate-skilled woodworkers.
The final project for wildlife in our grab-bag of other structures is one for a considerably smaller and perhaps less understood critter: solitary, tunnel nesting bees. This category of bees is a group of species within the class of native bees, which in Iowa is thought to number up to 300 species. Many of these species provide critical pollination services for Iowa’s plants and some garden crops. Solitary bees rarely sting, so attracting them to your yard or acreage by building a “Bee Hotel” won’t pose any additional risk and will be a fun project to learn about these interesting insects and maybe get some free pollination services in the making.
Habitat for humans
Once you’re done with all your woodworking for wildlife projects, you’ll be ready for a rest, and where better to take that break than outside, with nature and perhaps among the animals making use of your works. If you need a place to sit, I suggest one more project: the Aldo Leopold Bench. This bench, so named for the famous Burlington Iowa native author, wildlife biologist, forester, and environmental philosopher Aldo Leopold, is featured in many photos of Leopold and surely the type of structure where he made many of his famous observations and writings. Leopold was a champion for the conservation of wild things and wild places, a tinkerer, observer, and wood worker himself, a leader in early wildlife conservation efforts in the United States. This simple bench design adorns natural areas across the Midwest and is the perfect place to sit, observe and enjoy nature, and perhaps read (or re-read) a copy of Leopold’s most famous book, A Sand County Almanac.
Assembling your projects
Once you’ve decided to go to work for wildlife in the shop, here’s some pointers for all woodworking for wildlife projects:
- Use rot resistant wood and minimize paints and stains where possible.
- Use galvanized, outdoor screws.
- Stick to the designs to ensure the greatest probability of use by your targeted species.
- Put the project in the right places – study the species’ habitats your targeting and read online about best practices for placement to increase the chances the projects get used.
- Monitor use and keep them clean from year to year.
- Have fun!
The projects discussed above are just a small sampling of those that creative nature enthusiasts with some free time have figured out how to attract with wood and nail. If you can dream it, it seems someone has figured out how to make an artificial structure for it. There are structures that go underground for burrowing owls and those that float on the water for terns. Platforms that go high on telephone poles for ospreys and those that mount inside barns for barn owls. Boxes for winter roosts and those for summer roosts. And many more. If you don’t believe me, check out a copy of the wonderful book from the Minnesota Department of Natural Resources called Woodworking for Wildlife. There, or in searches online, you can find myriad of ways to apply your skill in the workshop on the waning days of this winter to create a summer home for many species of wildlife and even for those of us that love to watch them. Get to it, because spring will be here soon. I hope.