Black Tern Monitoring

One of the largest Black Tern breeding colonies in Michigan resides at St. Clair Flats.

Studies have shown that many smaller breeding colonies are disappearing, making the St. Clair Flats (SCF) colony especially valuable. Black Terns spend half their life flying over the ocean off the coast of Central and South America, and half breeding in U.S. and Canadian marshes. The birds create their nests on mats of vegetation floating in the water. Despite their charm and unique lifestyle, the birds are not well understood, and their populations are decreasing.

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We must act now!

If population numbers continue to drop, it will become increasingly difficult to restore the populations to sustainable numbers. Due to the urgent need for action, the Black Tern is receiving increasing attention from federal and state agencies. Only with continued research can we determine the causes of Black Tern population decline in Michigan and across North America.

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How is Detroit Audubon supporting Black Tern conservation?

Detroit Audubon has partnered with Audubon Great Lakes and National Audubon to monitor the St. Clair Flats (SCF) Black Tern colony since 2013. Detroit Audubon Research Coordinator, Ava Landgraf, monitors and bands the Black Terns at SCF between May 15th and August 10th while the birds are there breeding. With this data we can create an Integrated Population Model to better understand Black Tern population dynamics regarding the number of chicks successfully fledging and the number of adults returning year-to-year. Understanding these dynamics at SCF will allow us to see when issues are occurring (during nesting, post-nesting, migrating etc.) and enable us to develop and implement a plan to address those issues.

In 2019 and 2020 we saw a significant decrease in Black Tern numbers and nesting success at SCF. Our research is showing that high water levels, frequent storms and limited vegetation mats along with predators and boat traffic are all impacting the Black Terns ability to raise chicks. 

In 2021, we saw a slight increase in the number of adult Black Terns and a significant increase in nesting success which correlates with the large drop in water level. In addition to collecting baseline population data, we are using nest cameras to better understand the chick development process and what factors are contributing to nest failure. We also partnered with Audubon Great Lakes to apply nanotags (tiny radio telemetry devices) to juvenile Black Terns to learn about their fledging process and first migration south.

In 2022, we continued to experience lower water levels at SCF and saw many nests successfully hatching and fledging chicks. We also had great success with monitoring Black Tern nests using nest cameras. These cameras were set up to capture a photo every two minutes, allowing us to track the nesting process and chick growth without any disturbance to the nest.  At one nest we placed an artificial platform near a Black Tern nest to see if any terns would use it and the cameras allowed us to capture Black Tern chicks using the platform after their original nest fell apart.

For more information, check out the links below!

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Learn More and Get Involved!

If you are interested in supporting Detroit Audubon’s Black Tern monitoring, please contact our Research Coordinator, Ava Landgraf, at alandgraf@detroitaudubon.org.

To read our article Hopeful Re-Tern: Black Tern Monitoring in 2021, click here.

To view our webinar Black Tern Conservation at St. Clair Flats, click here. 

To view our webinar Terns in Trouble: How Lake Level Rise and Storms Impact Black Tern Nesting Survival webinar, click here.