Migratory Bird Treaty Centennial Bird of the Month
Eastern Bluebirds are harbingers of spring and represent a true conservation success story!
In 1916, the United States and Canada signed the Migratory Bird Treaty to protect birds across state and national borders. To celebrate 100 years of bird conservation, each month will feature a native Wisconsin bird species that has benefitted from the protection and cooperative conservation set forth in the Migratory Bird Treaty. For more information on the Migratory Bird Treaty Centennial and other Birds of the Month, visit dnr.wi.gov, keyword "bird treaty."
March's Migratory Bird Treaty Centennial Bird of the Month is the Eastern Bluebird (Sialia sialis). These colorful short-distance migrants experienced a dramatic population decline in the mid-20th century as a result of changing agricultural practices, loss of nest sites, and competition with non-native cavity-nesting birds such as the house sparrow and European starling. In response to these threats, concerned conservationists and citizens launched a campaign to place bluebird houses in suitable open habitats as early as the 1970s. Fortunately, bluebirds have responded well to such efforts, and populations are currently stable or increasing throughout their range. Today, bluebirds are fairly dependent on artificial nest sites, which replace the natural nesting cavities once provided more frequently by trees, snags, and other sources.
- Bluebirds are early migrants in the spring, reaching Wisconsin by March or April. A few even spend the entire winter in far southwestern Wisconsin counties!
- A testament to their population recovery, bluebirds ranked as one of the Top Ten most widespread nesting species during the first year of Wisconsin Breeding Bird Atlas II in 2015.
- As insectivorous birds, bluebirds were protected under the original Migratory Bird Treaty of 1916.
- Invasive bird species (such as house sparrows and starlings) can evict or haze bluebirds from nest boxes, so discouraging invasive species from using nest boxes is important, as are preventive measures against predators like raccoons and snakes.
- The Bluebird Restoration Association of Wisconsin has been instrumental in monitoring, nest box construction and habitat restoration efforts on behalf of bluebirds.