Washington has five nesting species of swallows, all insectivorous and highly migratory. They spend the spring and summer here, swooping above water and the forest tops eating insects, and then return to Central and even South America, to winter. They make this amazing journey back the following year and often return to the same areas to breed. Most do not survive their first year (as is the case with all birds), but some make it back and we are treated to their amazing, swooping, insect-eating flights.
“I hate swallows! They are nesting under my eaves and they make such a mess!” Sometimes I hear this complaint and I have to clarify which species we are talking about.
It is the barn swallow. They construct a cup-shaped nest of mud and grass, often under eaves of homes and barns. These birds have gorgeous purple shiny feathers and forked tails; they are sometimes called “scissor tails.” Barn swallows are usually the birds people find annoying due to the poopy mess that can accumulate under their nests. The Washington Department of Fish and Wildlife has a good web page with suggestions for dealing with barn swallows if they nest in an inconvenient location.
If the nest is in an unacceptable location, be sure to remove it as soon as the birds start to build, and keep removing it. Barriers of mesh netting can be installed if under an eave or other location where it could be installed (use appropriate mesh size in thick mesh so birds do not become entangled). Foil or other smooth metal can be placed over the preferred spot to prevent future mud from sticking too.
Cliff swallows also build a mud nest, which looks like a gourd with a hole in it. These birds are colonial and are usually found under highway bridges or on natural cliffs, so are seldom a problem for landowners.
Two species, the bank and rough-winged swallows, will actually tunnel into fine soil appropriately configured along eroding river banks or even stock-piled highway building materials. They are colonial nesters and there can be hundreds of burrows in a colony, many of which exist for years and years.
Swallows in the Forest
The swallows most closely associated with forests — the ones that use cavities in dead trees and sometimes nest boxes — are tree swallows and violet-green swallows. These two cavity-nesting species prefer to use abandoned woodpecker nest cavities for their annual nesting activities. They arrive in spring (the dates vary by locale), and will stake out a territory based around an available cavity or nest box. In late April and May they will build a grass nest in the cavity, line it with feathers, and produce one or two broods between arrival and early summer. The young birds will hang around the nesting area for the first few weeks after coming out of the nest, and then in early fall, they all head south. Just before migration large groups of swallows are sometimes seen congregating on wires, getting ready to go.
Tree and violet green swallows are white on the belly and both have a gorgeous, shiny blue color. Violet green swallows are slightly smaller with longer wings that reach down past their tail and striking white patches on their face.
Nest Boxes
Both tree and violet green swallows will readily take to nest boxes, particularly those placed in the open near water. Boxes for these wonderful birds can be mounted on fence posts, poles or trees with a clear flight path to the open. They can be placed relatively close together (30-50 feet), but not facing each other, as they seem to not like having neighbors!
Boxes should be built to basic standards with a 1.25” to 1.5” entrance hole about 7” above the bottom of the box. They can be constructed from 1” x 6” wood, and it is best if the back of the entrance door is rough to enable baby birds to climb out. Good plans for a swallow box are found at https://wdfw.wa.gov/living/projects/basic_songbird.html. Once per year, preferably in the fall or winter, boxes need to be cleaned out to allow for a new nesting attempt the following year. If not cleaned, they will be used again until they are full. Old nest material can contain parasites and should be removed. A maintained box will be used by swallows for many years.
It is not necessary to make boxes out of cedar (as recommended in some plans); it is likely that the box will crack and fall off of the mounting place long before it rots. The author has several dozen boxes around his property in eastern Washington and enjoys the annual spectacle of swarms of nesting tree and violet green swallows flying about his home.
These beautiful birds are one of the beneficiaries of retaining standing dead trees (snags) on your small forestlands. Please help them and many other species by leaving standing dead trees of at least 8” in diameter. Remember, about 40 percent of forest wildlife is dependent on dead wood, or “wildlife trees” of some kind. Swallows are beautiful, greatly beneficial birds that help us by eating many, many insects (including mosquitoes) and gracing our lives with their beauty.
Let me know if I can help you with wildlife habitat on your forestlands, and send me pictures of your cavity and nest box habitats in use!
By Ken Bevis, DNR Stewardship Wildlife Biologist, Ken.Bevis@dnr.wa.gov
Small Forest Landowner News 