By Michael Rohwer
These are heady days for birders. My friend, an avid bird watcher, tells me that more and more species have been appearing near her home over the years.
These new sightings may be a sign of something bigger—bird species spreading into new territory may be an indicator of a changing climate. In fact, all “canary-in-the-coal-mine” references aside, birds make particularly good indicators of environmental change for several reasons:
- Each species of bird has adapted to certain habitat types, food sources, and temperature ranges. In addition, the timing of certain events in their life cycles—such as migration and reproduction—is driven by cues from the environment. Changing conditions such as warming temperatures can influence the distribution of both migratory and non-migratory birds.
- Birds are easy to identify and count, and there is a wealth of scientific knowledge about their distribution and abundance. People (like birders) have kept detailed records of bird observations for more than a century.
- There are many different species of birds living in a variety of habitats, so if a change in habitats or habits occurs across a range of bird types, it suggests that a common force might be contributing.
The National Audobon Society’s observational data, featured in EPA’s Climate Change Indicators in the U.S. Report, shows that the average bird species shifted northward to winter by 35 miles from 1966 to 2005. These trends are closely related to winter temperatures. Of the 305 species studied, 58% have shifted their wintering grounds significantly northward since the 1960s, though some others haven’t moved at all or move for other reasons (e.g., habitat alteration, food availability). This graph shows that shift north over time:
Some bird species adapt to generally warmer temperatures by changing where they live by migrating further north in the summer but not as far south in the winter. With more than 500 local chapters, the National Audobon Society makes it easy to collect vital data, through its annual Christmas Bird Count, the new Coastal Bird Survey, and other initiatives. I plan to dedicate some weekend mornings to birding. How about you? Maybe we’ll spot each other participating in the Christmas bird count so our observations can help tell the story of how bird wintering grounds are changing.
About the author: Michael Rohwer is a recent ORISE Fellow supporting the communications team in the Climate Change Division within the Office of Air and Radiation. When he’s not pursuing a career in protecting human health and the environment, you can find him enjoying gardening and sports.