Birds of Yellow River State Forest |
Stay in the Loop |
Yellow River State Forest is a Globally Significant Bird Area, and is home to many birds not common in the Upper Midwest. On this page we will sharing information about various birds that can be found in YRSF. We will be adding additional species in the coming months.
|
|
A Cerulean Warblers female pictured on the left, a male on the left. Photos courtesy of Kat Busse.
|
Cerulean Warbler
Life and Habitat
The decline in cerulean numbers is generally from habitat loss and or habitat fragmentation. The bird prefers large diameter trees (oak or walnut) in deciduous forests which have “canopy gaps,” and a source of water (stream) nearby. It’s theorized canopy gaps allow the warbler to benefit from greater vegetative growth and therefore greater insect concentration. If you wish to spot them, and it’s the right time of year, look midway to upper layers in oaks or walnuts of large diameter. Their nest may be hard to spot since research indicates it is often shielded from flying predators by overhanging vegetation. They venture from the nest to look for caterpillars or other insect sources (insectivores). Look for them hopping along the branch. They also choose nesting sites along steep slopes or ravines overlooking a road or a river.
They only have one brood per year with three to four in a clutch. Their nest is made of woven fibers (often grapevines and bark) “glued” together with spider webs. Most interestingly researchers have found their nests are clustered with species settling near one another. This is known as “conspecific attraction.” You will see this on the map. Luckily the YRSF offers habitat that the cerulean favors as well as an annual reoccupation of nesting sites. Therefore birding opportunities (late April through mid-July) are good, but the bird is often difficult to observe in high canopies of large diameter trees. Be patient, use binoculars and listen for the male’s buzzy song. They leave mid-July for its wintering range in the northern Andes of Central America. There they congregate in fir trees.
Identification
The cerulean male is 4.5 inches long, sky blue on top and nearly all white below and has a mass of 2 nickels. The female is more drab (as in many species for camouflage during nesting) with a yellowish underbelly and appears olive green from above (see pictures).
Sounds
The key to locating a Cerulean is its song as the birds are usually high and often hidden in the forest canopy. But the male’s distinctive song is loud and memorable. “Zero zero za za za zureeee” or “tzeedl, tzeedl ti ti ti tzeeee”.
Male: https://www.allaboutbirds.org/guide/Cerulean_Warbler/sounds
Habitat in YRSF
Estimates of experts vary, but Cornell University estimates there has been more than a 70 percent decline in the worldwide Cerulean Warbler breeding population between 1970 and 2014, mostly due to habitat loss and degradation in nesting and wintering areas. Overall, that is grim news for the species, but here in YRSF Cerulean Warblers are doing well.
Jon Stravers, Kathleen Carlyle, and Dr. Paul Skrade of Driftless Area Bird Conservation released a report in 2020 on the Cerulean Warbler that is the culmination of more than 12 years of investigation in several local study areas including Yellow River State Forest, Effigy Mounds National Monument, Pikes Peak State Park and Sny Magill Complex within Pool 10 of the Upper Mississippi River National Wildlife and Fish Refuge.
Their report is significant in that other similar studies in traditional breeding areas of the eastern United States have documented a decrease in the presence of this bird, but here in Northeast Iowa the number of sites where they nest and the number of birds at the sites has held steady during the 13-year study.
High rates of reoccupation of Cerulean territories may be of special importance in light of dramatic declines of Cerulean Warblers reported in other studies in North America according to Stravers,
Ceruleans doing well here to good forest management at YRSF led by Forester Bruce Blair, as well as the presence of large tracts of forest and bordering land undisturbed by industry or intensive agriculture practices, says Stravers. Forestry practices such as long rotation timber extraction and selective logging to create natural canopy gaps and uneven-aged forest stands are very beneficial to the species.
Blair says, "There are most likely a number of factors combined that contribute to the abundance of Cerulean Warblers. We are aware there are many ceruleans warblers here and so we have the responsibility to manage the forest appropriately in a way to limit negative impacts and try and promote management practices that will yield positive impacts."
Life and Habitat
The decline in cerulean numbers is generally from habitat loss and or habitat fragmentation. The bird prefers large diameter trees (oak or walnut) in deciduous forests which have “canopy gaps,” and a source of water (stream) nearby. It’s theorized canopy gaps allow the warbler to benefit from greater vegetative growth and therefore greater insect concentration. If you wish to spot them, and it’s the right time of year, look midway to upper layers in oaks or walnuts of large diameter. Their nest may be hard to spot since research indicates it is often shielded from flying predators by overhanging vegetation. They venture from the nest to look for caterpillars or other insect sources (insectivores). Look for them hopping along the branch. They also choose nesting sites along steep slopes or ravines overlooking a road or a river.
They only have one brood per year with three to four in a clutch. Their nest is made of woven fibers (often grapevines and bark) “glued” together with spider webs. Most interestingly researchers have found their nests are clustered with species settling near one another. This is known as “conspecific attraction.” You will see this on the map. Luckily the YRSF offers habitat that the cerulean favors as well as an annual reoccupation of nesting sites. Therefore birding opportunities (late April through mid-July) are good, but the bird is often difficult to observe in high canopies of large diameter trees. Be patient, use binoculars and listen for the male’s buzzy song. They leave mid-July for its wintering range in the northern Andes of Central America. There they congregate in fir trees.
Identification
The cerulean male is 4.5 inches long, sky blue on top and nearly all white below and has a mass of 2 nickels. The female is more drab (as in many species for camouflage during nesting) with a yellowish underbelly and appears olive green from above (see pictures).
Sounds
The key to locating a Cerulean is its song as the birds are usually high and often hidden in the forest canopy. But the male’s distinctive song is loud and memorable. “Zero zero za za za zureeee” or “tzeedl, tzeedl ti ti ti tzeeee”.
Male: https://www.allaboutbirds.org/guide/Cerulean_Warbler/sounds
Habitat in YRSF
Estimates of experts vary, but Cornell University estimates there has been more than a 70 percent decline in the worldwide Cerulean Warbler breeding population between 1970 and 2014, mostly due to habitat loss and degradation in nesting and wintering areas. Overall, that is grim news for the species, but here in YRSF Cerulean Warblers are doing well.
Jon Stravers, Kathleen Carlyle, and Dr. Paul Skrade of Driftless Area Bird Conservation released a report in 2020 on the Cerulean Warbler that is the culmination of more than 12 years of investigation in several local study areas including Yellow River State Forest, Effigy Mounds National Monument, Pikes Peak State Park and Sny Magill Complex within Pool 10 of the Upper Mississippi River National Wildlife and Fish Refuge.
Their report is significant in that other similar studies in traditional breeding areas of the eastern United States have documented a decrease in the presence of this bird, but here in Northeast Iowa the number of sites where they nest and the number of birds at the sites has held steady during the 13-year study.
High rates of reoccupation of Cerulean territories may be of special importance in light of dramatic declines of Cerulean Warblers reported in other studies in North America according to Stravers,
Ceruleans doing well here to good forest management at YRSF led by Forester Bruce Blair, as well as the presence of large tracts of forest and bordering land undisturbed by industry or intensive agriculture practices, says Stravers. Forestry practices such as long rotation timber extraction and selective logging to create natural canopy gaps and uneven-aged forest stands are very beneficial to the species.
Blair says, "There are most likely a number of factors combined that contribute to the abundance of Cerulean Warblers. We are aware there are many ceruleans warblers here and so we have the responsibility to manage the forest appropriately in a way to limit negative impacts and try and promote management practices that will yield positive impacts."
