The Cerulean Warbler was once one of the most abundant breeding warblers in the Ohio and Mississippi River Valleys; now it is one of North America’s fastest declining songbirds. Since 1966, the Cerulean Warbler population has decreased by almost 70 percent.
Michigan is part of the warbler’s northernmost breeding range with the largest state numbers concentrated in the Allegan State Game Area. The annual decline in ceruleans in Michigan at 4.3 percent is higher than the range-wide decline of three percent. The culprit for such a severe Cerulean Warbler population decrease in Michigan is habitat loss and fragmentation.
The Cerulean Warbler prefers a breeding habitat of 3,000 hectares or greater of mature deciduous trees situated near a river system. The small warbler, which is colored sky blue with streaks of white and black, spends most of its time in the upper canopy foraging for insects. The Cerulean Warbler’s color and preference for breeding high in the forest canopy make it an elusive bird for birdwatchers and scientists. As of 2009, the Michigan Department of Natural Resources lists the Cerulean Warbler as a State Threatened species.
Current research lists six primary threats to the Cerulean Warbler’s breeding territory which includes: loss of mature deciduous forests, fragmentation of deciduous forests, emphasis on even-aged forest management and shorter harvest rotation periods, environmental degradation, loss of key tree species and nest parasitism by the Brown-headed Cowbird. The United States Geological Survey indicates if nothing is done to protect the Cerulean Warbler by 2046, the Allegan State Game Area population could become ecologically extinct.
With that information in hand, Michigan Audubon set out to make a positive impact on this threatened warbler. In 2012, Michigan Audubon hired its first Cerulean Warbler monitor who surveyed Allegan, Barry, Jackson and Washtenaw counties. Now with the second year of monitoring complete, over 2,000 checklists have been submitted to the Cornell Lab of Ornithology via the citizen science tool, www.ebird.org, in association with the Cerulean Warbler monitoring project.
The checklists submitted have helped create a more accurate metric allowing the comparison of the number of birds heard per hour while birdwatching. For example, statewide, 9.6 Cerulean Warblers are heard per hour of birdwatching, compared to 6.5 Sandhill Cranes and 30.2 Canada Goose heard per hour.
“We are frequently asked ‘How many Cerulean Warblers are there at Location X?’” says Tom Funke, Michigan Audubon’s Conservation Director. “It is important to keep in mind that this monitoring project does not count each individual bird, but rather collects a sampling of the bird in a certain area year after year. This type of data collection will help identify trends over a long period of time and provide ornithologists and biologists better insights into Cerulean Warbler breeding populations.”
Conservation action plans have recently been implemented and include activities such as mapping wintering, migratory and breeding ranges, and preventing permanent loss of large forest habitats in the birds’ breeding range. The U.S. Fish and Wildlife Service, Division of Migratory Bird Management states, “An over-riding need (…) is continued research to help fill critical information gaps in our knowledge of this species and monitoring of [the Cerulean Warbler’s] response to conservation actions.”
Although it is too early to distinguish any type of trend from Michigan Audubon’s Cerulean Warbler monitoring project, efforts are in line with all other conservation groups involved in the warbler’s survival, with a bottom line to permanently remove the bird from state and federal lists.
For additional information or photos to use with this announcement, contact Michigan Audubon’s, Marketing and Communications Coordinator, Mallory King at firstname.lastname@example.org or 517-641-4277.