August 2024 Bluebird Trail Update

Photo: Bluebird eggs in Box 5, April 2024 by George Coleman

by Kurt Miske, WCAS Board Member and Bluebird Trail Coordinator

As many members know, WCAS is responsible for nine bluebird nesting boxes in the open area along the edge of Cleveland Metroparks’ property which also features Lewis Road Riding Ring. Working in conjunction with the Metroparks, WCAS obtained and installed five nesting boxes in 2021. A Boy Scout Eagle project, permitted by the Metroparks, added four boxes in 2023. To date, these boxes have resulted in 33 Eastern Bluebird fledglings and 44 Tree Swallow fledglings! Currently there are five more young bluebirds and nine more young Tree Swallows that should be fledging soon. And the 2024 breeding season isn’t over yet! 

Bluebird trails are much more than simply building and installing nesting boxes in strategic locations. Once the boxes are in place and the month of March begins, monitoring also begins. If the boxes are existing (i.e. have been up all winter), they need to be cleaned in preparation for the arrival of the birds. Boxes are checked every week or so to watch for nest-building. Monitors ascertain what type of bird is building a nest. If it is a native bird, typically an Eastern Bluebird or a Tree Swallow, we note the progress being made. If eggs are present, the frequency of the monitoring increases to about every three days. We track the number of eggs, the number that hatch, and when the birds fledge. After the young fledge and the adults leave, the box is cleaned and made ready for either another brood or over-wintering. 

Each box is built with a side that opens like a door. This facilitates making accurate observations. The adults tolerate occasional short checks. On some occasions, the female bird may not leave the nest when the monitors open the door! The female typically lays one egg per day. Because we know the day the last egg was laid we can determine when the eggs will hatch and when the chicks will fledge. We also are able to calculate the day when the chicks are developed enough that we should no longer open the door as a chick could ‘escape’. Once out of the nest, a chick will not tolerate being reintroduced to the nest. 

Monitors not only record data, but also help keep the nest boxes safe for the intended occupants. Our boxes, like almost all nesting boxes, have predator baffles (pictured) that help keep out such enemies as raccoons, cats, and snakes. But there are other possible threats that the monitors must detect and eliminate, such as wasps and lice. The biggest problem we have is with House Sparrows. If a House Sparrow enters a box containing a bluebird or Tree Swallow, the House Sparrow will brutally murder the other bird. The House Sparrow may even build a nest on top of the dead bird and any existing eggs or hatchlings.

House Sparrow breeding season starts before either bluebird or Tree Swallow breeding season. This is facilitated by the fact that House Sparrows are year-round residents, whereas bluebirds and Tree Swallows migrate to the breeding area. Monitors must be aware of House Sparrows constructing nests before bluebirds or swallows arrive. While federal law prohibits harming the nest of native birds, House Sparrows are not native. To date, we have not allowed a single House Sparrow to fledge from our nest boxes.

We have another tool to control House Sparrows, a device called a sparrow-spooker (pictured) that is built and installed as needed. For some reason, House Sparrows do not like the fluttering strips of Mylar, yet bluebirds and Tree Swallows are not bothered by them and are often seen using the sparrow-spooker as a perch. As soon as a monitor finds a native bird’s egg in a nest, a sparrow-spooker is installed on the box. Sparrow-spookers must only be used when the box is occupied; otherwise sparrows would get used to them and they would lose their effectiveness.

Photo: Box 8, June 2024, showing sparrow-spooker & predator baffle, by Kurt Miske

WCAS has been extremely fortunate to have George Coleman and Alisa (Lisa) Gerbec as monitors from Day 1 in 2021. They have had a hand in helping each fledgling that the trail has produced. They have cleaned boxes, kept up the spreadsheets we use to record data, and done anything else that needed to be done. Also helping out when her educational pursuits allow is Jess Kowalski. Many, many thanks!

Data is tabulated and submitted to both Cleveland Metroparks and Cornell’s NestWatch on a yearly basis. We hope to continue for years to come.