The Hermit Warbler is a songbird that lives its life in two areas of the world. It spends its breeding season (late May-early July) in the coniferous forests of the Pacific Northwest (PNW) and migrates to Central America for the winter. Due to the long journey from the Central America to the PNW, it is dependent on food resources being available throughout its journey and when it arrives to breed. The environmental conditions across its range are tightly linked to habitat resources, and unfavorable climatic conditions, such as those becoming less frequent due to climate change, can negatively affect bird populations. Changes in bird populations are not always easy to notice, especially with small songbirds that live high in tree canopies. Studying birds for one or a few years may not be enough to signal the change in their well-being.

A Hermit Warbler singing on a lichen-covered branch in the forest canopy. Male Hermit Warblers will defend their territories ferociously against other males during the breeding season. H.J. Andrews Experimental Forest, May 2017.

Fortunately, long term data sets are becoming more available thanks to long term study programs. For example, the Willamette National Forest in Oregon is home to H. J. Andrews Experimental Forest (the Andrews). Designated by the USDA Forest Service Pacific Northwest Research Station, the Andrews forest hosts many forest research projects and has been monitored since 1948. In 1980, it was became one of the National Science Foundation’s Long Term Ecological Research sites ensuring that it will remain a resource for scientists for years to come. Bird surveys at the Andrews began 11 years ago, and researchers at Oregon State University are beginning to draw connections between changing climate and bird communities in relation to the forest’s structure and compositions.

H.J. Andrews Experimental Forest, where long-term bird study is launched in 2009 by Drs. Matt Betts and Sarah Frey. The forest sits on the moist foothills of western Cascades in Willamette National Forest.

One of these researchers, Hankyu Kim PhD student in the Department of Forest Ecosystems and Society, is using this data to study the Hermit Warbler and other bird species at the Andrews. Hankyu is interested in how and why bird communities are changing over time. With 11 years of bird observations and extensive temperature data, he is attempting to estimate how population of birds persist in the forests. To begin approximating how current climate effects birds, we need to have an idea about bird communities in the past. Past conditions can help us explore how birds might respond to future climate scenarios. Without the effort of many researchers before him to monitor birds, his investigation would be impossible.

Bird surveys are conducted via point counts. Researchers stand at a point count station for 10 minutes and count all bird species they see and hear. Listen to a hermit warbler and some other background birdsongs recorded at H.J Andrews in June 2017.

Hankyu realized the importance of long-term data after reviewing the 45-years of wintering waterbird surveys collected by the Birdwatching Club at Seoul National University, Korea during his time as an undergrad. The group took annual trips to the major Rivers and Coastal Areas, and in just a couple decades the members of the club had recorded declines and disappearances of some species that were once common and widespread. This finding inspired Hankyu to pursue graduate school to study unnoticed or uncharismatic species that are in danger of decline. Every species plays a critical role in the ecosystem, even if that role has not yet been discovered.

Tune in on Sunday May, 19 at 7 pm to hear more about Hankyu Kim’s research with birds. Not a local listener? Stream the show live or catch up when the podcast episode is released.

Want more about the Hermit Warblers in Oregon? Check out this video of Oregon Field Guide featuring Hankyu and some of his colleagues from Oregon State University.