With the sweet sounds and sights of spring upon us, it’s time to introduce an exciting addition to the CVWMA! If you have been out at Duck Lake over the winter months, you may be wondering about the sudden appearance of a barn-like wooden structure along the southeastern border of the Duck Lake Nesting Area. Surprise! It’s our new Barn Swallow nesting structure! Built in late autumn of 2024, the structure was designed to provide nesting habitat for the federally threatened Barn Swallow (Hirundo rustica). For those of you who are familiar with the Swallow Hotel of Corn Creek Marsh, this structure utilizes the same concept of “over-engineered construction” to create 1m x 1m ceiling nesting compartments formed by the intersections of wooden beams (see photo). Barn Swallows can nest either solitarily or in colonies, though they prefer not to see their nesting neighbours in a colonial situation – privacy please! The nesting compartments help maximize the available surfaces for nesting, while providing a visual barrier between adjacent nests. The structure is clad with an insulated galvanized metal roof to help reflect solar radiation and reduce heat transfer, as data collected in recent years in the Swallow Hotel showed temperatures reaching above 35°C in the summer months! We want to ensure that any nesting structures erected by CVWMA provide a safe environment in which our feathered friends can successfully raise their young.

Though the new structure is overall quite similar to Corn Creek’s Swallow Hotel, it boasts a 40% increase in size. This increased size should translate to a greater capacity to host breeding Barn Swallow pairs. The interior of the Swallow Hotel contains 40 ceiling nesting compartments, and this structure accommodated 19 pairs during the 2024 breeding season. With 60+ nesting compartments in the new Duck Lake structure, we are hopeful that over time, this nesting structure will accommodate upwards of 40 Barn Swallow pairs. In addition to the nesting compartments, there are also a variety of wooden ledges for Barn Swallows to construct natural nests upon. The structure is outfitted with 72 locally made prefabricated wooden nest cups, installed by CVWMA staff in late February.  Prefabricated nest cups allow Barn Swallows to dedicate more energy to offspring production instead of nest building. They also prevent nest fall, which unfortunately sometimes happens with naturally constructed nests. During nest cup installation, we found evidence of an unexpected visitor to the structure – a Great Horned Owl! While we are glad to have provided shelter to such a magnificent creature during the last vestiges of winter, we hope that this fearsome hunter moves on to a different roost before the swallows arrive in mid-April. In the coming weeks, a perch wire will be erected adjacent to the structure. Perch wires are used both by adults in between foraging trips, and by fledglings that need a safe place to rest while they take a break from flying lessons!

While we invite you to go take a look at the new nesting structure, we kindly ask the public to refrain from entering the structure from May to September. This measure is in place to avoid causing disturbance to both nesting birds and birds that may be investigating the structure as a potential nest site for next year’s breeding season. In late summer, Barn Swallows are known to evaluate potential future nesting sites before they migrate south, so we are not necessarily expecting the new structure to be heavily occupied during the 2025 breeding season, as many birds that have previously bred in the area will likely have already chosen their nesting sites. However, we are hopeful that with time, more and more pairs will be attracted to nest within the structure. As with the Corn Creek Swallow Hotel, CVWMA staff will monitor the new structure weekly for nesting activity in the 2025 breeding season and for at least another four years thereafter. The long-term goal of providing this nesting habitat is to increase the number of Barn Swallows breeding within the Creston Valley to help combat the overall decline of local aerial insectivorous species. While contributing to the biodiversity of the Creston Valley, and beside the aesthetic and intrinsic value they provide to our environment, Barn Swallows play an important role in insect control and nutrient cycling, and are key indicators of our ecosystem health. The next time you visit the CVWMA wetlands, whether at Corn Creek, Duck Lake, or anywhere in between, keep your eyes peeled for a glimpse of these iconic birds!

 

 

Marc-Andre installing nest cups (left); ceiling nest compartments (right)