Tree Swallow Nest Box Project – 2026
The Friends of Cedarburg Bog are continuing to maintain the 78 Tree Swallow and Bluebird nest boxes originally installed at the UWM Saukville Field Station 36 years ago. We are committed to preserving this housing complex for our wonderful native aerial acrobats. On February 22, eighteen volunteers cleaned, maintained, and replaced nest boxes to prepare them for the spring arrival of our tenants. By examining the 2025 nesting material in the boxes they also recorded last year’s usage.
One of two nest box grids at the Field Station. This one in the big prairie at the corner of Blue Goose and St. Augustine Roads.
Because of the age of the boxes, many are deteriorating to the point where they need to be replaced. Over the past three years we have replaced 20 of the 78 nests with newly constructed boxes. Over the next few years, the Friends plan to replace the remaining 58 old boxes as they become no longer serviceable.
Our volunteers found that 74 of the 78 boxes were used in the 2025 nesting season. 64 (82%) of the boxes had Tree Swallow nests; 4 had Bluebirds; and 6 had House Wrens. Undoubtedly, some of the Tree Swallow nests were not successful at fledging young in 2025. However, with 3 to 4 fledglings from the average successful Tree Swallow nest, there were likely over 100 young swallows produced by the efforts of FOCB volunteers in 2025!
One of our new nest boxes with last-year’s nest
