Which bird can sing their song from birth? Willow Flycatchers! These small, olive-colored birds, unlike many bird species, don’t learn their song from their parents; instead, they are born already knowing their calls. Willow Flycatchers are visually identical to Alder Flycatchers but can be distinguished by the males’ distinct fitz-bew call used to defend their territories.
There is still little scientific data published on this species, making them a bird of great mystery. There is a key publication called Little Green Bird, written by Bob McCabe, that goes into great depth about the Willow Flycatchers’ behaviors. More information on this book can be found in one of our previous features.
Population
Willow Flycatchers have a large geographic range and are currently listed as a species of least concern. However, their population is in decline from habitat loss. From 1966 to 2019, the population has decreased 25%.
Nests
Willow Flycatcher nests are small, about 3 inches long by 3 inches tall and built out of small grasses and twigs. The nests also have soft materials used on the exterior, including cattail fluff, spider webs, and sometimes down feathers from other birds. This helps make their nests distinct from many other birds. American Goldfinch nests are the same size and use similar nesting material, but their eggs can help distinguish the two nests.
Willow Flycatchers typically have a clutch size of three to five eggs. If you find a nest that has less than 3 eggs, it is likely that the female is still laying. The female lays one egg every day or two. The whole egg laying process can take between seven to ten days to complete. Willow Flycatcher eggs are cream-colored, with reddish brown spots appearing only on the edge of the eggs making them unique among other birds nesting at Goose Pond Sanctuary.
Feather-lined Willow Flycatcher nest built of grass, with four speckled eggs (photo by Carolyn Chee).
The similar-looking nest of an American Goldfinch, with two plain eggs (photo by Carolyn Chee).
In his study on Willow Flycatchers, Bob McCabe found 9% of nests contained Brown-headed Cowbird eggs. However, the Cornell Laboratory of Ornithology states: “If a Willow Flycatcher finds a cowbird egg in their nest, they may stuff it into the wall of the nest or in some cases, may build a brand new nest on top of their original one. This ensures the cowbird egg won’t be incubated.” Our study at Goose Pond Sanctuary (more on this below) found no cowbird eggs in Willow Flycatcher nests.
The Willow Flycatcher project
In 2020, volunteer JD Arnston started Willow Flycatcher surveys at Goose Pond Sanctuary. He primarily focused on counting singing males, which proved that the sanctuary has good Willow Flycatcher habitat.
This year, JD and I collaborated on the project. With the help of volunteers, we incorporated nest searches in addition to the singing male surveys, in hopes of getting more information on shrub preference for nesting. Knowing their nesting shrub preference will let us know which shrub species to plant to help accommodate these little birds’ needs.
On Monday, June 26, volunteers went out with me and Emma Raasch to conduct nest searches in the wetland scrapes west of Goose Pond. We found five Willow Flycatcher nests, along with old Red-winged Blackbird nests and a few American Robin nests that were still active. Some of the flycatcher nests found were either empty or only had a few eggs, indicating the females were most likely still in the process of laying.
On July 2, JD, Mark Martin, and I went out with six volunteers to Benade Prairie to continue conducting nest searches and found four more Willow Flycatcher nests.
Map of nest locations and singing males heard at Goose Pond Sanctuary and Otsego Marsh in 2023 (graphic by Carolyn Chee).
All of the properties where the singing male surveys were done were searched for nests. Throughout the breeding season, 63 singing males were heard, and 21 nests were found at Goose Pond Sanctuary. It is likely some nests were not found. All nests found were within an acre of where the singing males were heard, as seen in the aerial photos above.
Project findings so far
While the results are still in the preliminary stages, Willow Flycatcher nests found in the Goose Pond area this year were found in multiple shrub species, including red-osier dogwood, American elderberry, American hazelnut, non-native honeysuckle, and willow species.
According to Bob McCabe’s study, nests were found in elderberries 58% of the time, with red-osier dogwoods at 26%. However, at Goose Pond Sanctuary, red-osier dogwood was the dominant nesting shrub, at 33.3% and American elderberry was second at 28.6%.
Shrub species with Willow Flycatcher nests (graph by Carolyn Chee).
Benade Prairie, which has primarily red-osier and silky dogwood, had six nests in dogwood shrubs. However, the wetland scrapes, which have several shrub species available, had nests in American hazelnut, American elderberry, non-native honeysuckle, American plum, red-osier and silky dogwood, and willow species. Therefore, shrub species may not be the determining factor for good nesting habitat—the true indicator may be proximity to water and food.
The future of the project
Based on the project results, I am now putting together a document for anyone interested in attracting Willow Flycatchers to their property and writing a draft conservation management plan to help manage the species in the future at Goose Pond Sanctuary.
Willow Flycatcher nest (photo by Carolyn Chee).
We are hoping to get more volunteers involved with singing male surveys and nest searches again in 2024. Singing male surveys will be done in June in the last 30 minutes before sunset. This is when males are singing the most and if you’re lucky you might even see one perform a skydance! Nest searches will be done during the day in June and July and involve hiking through the prairie, sometimes through dense vegetation.
If you’re interested in joining or want to learn more about attracting Willow Flycatchers to your property, please email Goose Pond land steward Graham Steinhauer!
Written by Carolyn Chee, masters student at the University of Wisconsin-Madison Nelson Institute of Environmental Studies
Cover image by Arlene Koziol. An olive-colored Willow Flycatcher is perched on a thin branch.
