Swallows and Bridges Community Science Project

By GEAS Guest Blogger Terry Rich

As a partner in the Idaho Bird Conservation Partnership, Golden Eagle Audubon Society is embarking on a new community science program – Swallows and Bridges. You can help!

The goal of this program is to educate Treasure Valley citizens about the conservation of aerial insectivores. These are species that eat primarily by flying around and catching insects in their mouths. Many species of bats are in this group, but I’ll be talking about birds. Aerial insectivore birds in Idaho include swifts (4 species), nightjars (2 species), flycatchers (22 species), and swallows (7 species).

Declining Insect Populations

Most of these species have declining populations because of the wholesale decline of insects around the world. That decline is estimated at 32% since the 1970s across North America. Insects are declining for a variety of reasons, but the use of pesticides is high on the list of villains. I cringe every time I see a “pest control” company in my neighborhood spraying chemicals from a large tank on lawns and around houses. Don’t do it. Check out more environmentally friendly solutions. Those include providing habitat for birds who eat insects and adding better insects to your yard (ladybugs and mantids) who eat worse insects.

Barn Swallows and the Cliff Swallows nest under bridges in Ada County and are the subject of this community science project. Hence the title of our project – Swallows and Bridges.

Barn Swallows by Terry Rich

831 Bridges to Monitor

Thanks to the Ada County Highway Department, I learned there are 831 bridges and “large culverts” in Ada County. They gave me a file of the locations of each of these that can be viewed in Google Earth. The aim of the project is to visit each of these bridges and document which species and how many individual birds use each site.

Here's where you come in. You can check the bridges and culverts in your neighborhood and tell us what swallows you found and how many. This can be done in single visit. You probably know about the bridges in your neighborhood. These might be quite small. I have two bridges in my neighborhood that host barn swallows and they both span a small canal. One bridge has a single barn swallow pair and the other three or four.

You are free to visit your bridges as often as you like. You can also visit other bridges you may cross from time to time, for whatever reason. The more visits, the better. Data will be used to contribute to the large-scale understanding of these species.

Everyone is welcome to participate. Please register as a Golden Eagle Audubon Society volunteer if you haven’t already and then sign up for this cool project.

Reduce the Use of Pesticides to Protect Insects and Birds

We also plan to place educational plaques on some bridges. We will convey suggestions on what people can do to make the lives of these birds better. Those include, 1) reduce or eliminate the use of pesticides in your yard, 2) plant native flowering and fruiting species, and 3) replace bluegrass lawns – a biological desert for most species – with native species.

The idea of increasing the number of insects may put some people off. But most of the insects gobbled up by swallows are invisible in our daily lives. And these birds also get some mosquitos, flies, and gnats that might annoy us from time to time.  

Cliff Swallows by Ken Miracle

Barn Swallows and Cliff Swallows

Let’s take a closer look at our two swallows. There are 86 species of swallows on the planet, but few are more beautiful than our Barn Swallow. This is the most common and widely distributed swallow in the world. Our birds leave in winter to spend the non-breeding season from central Mexico to the tip of South America.

They begin to return in the middle of March but don’t hit peak numbers until about the middle of May. There is a further increase once young are out of the nests and joining the adults flying around and sitting on wires. That peak occurs in the third week of August. Birds start to leave our area around the first of September and are completely gone by the middle of October.

Unlike Barn Swallows, Cliff Swallows occur only in the Western Hemisphere. They winter over a good portion of western and central South America. Cliff Swallows arrive and peak on about the same schedule as Barn Swallows, but they don’t show the same late summer peak. They clear out by the first of October.

For our purposes, it doesn’t matter when you visit bridges to count swallows. Even if you are very early or very late in the season, a count of zero birds is useful. “Nothing is something” in the world of science. We will try to get multiple counts in the window when the most birds are around – from the middle of May to the middle of August.

Immature Barn Swallows by Ken Miracle

Count Birds But Not the Nests

Because both species build mud nests attached to and under bridges and culverts, we do not expect you to try to count nests. In fact, we don’t want you even trying because we don’t want to harass nesting birds. We’ll just be looking for a count of birds sitting and flying around. This can be quite challenging where there are large numbers of birds swirling in the sky. But following eBird guidance, we will do the best we can.

If you are interested in counting swallows at one or more bridges in Ada County, please use this link to register as a Golden Eagle Audubon volunteer and sign up for this project. We will give you the simple Google Form that we’ll use to report birds, and the official name of the bridge or culvert Ada County has assigned.

For now, we are just working in Ada County. But if this goes well, there’s no reason we can’t expand to surrounding counties. And states. Please join us!

You can reach Terry at terryrichbrd@gmail.com or send the requested information to swallowsandbridges@gmail.com.