Wildlife researchers and scientists use aquatic birds as environmental change indicators in freshwater and marine environments. For about 50 years, herring gulls have been used to get a better idea of how the Great Lakes are changing through time, and have found in that time period a decline in volume and density. Read the full story by Great Lakes Echo.
Great Lakes Commission
https://www.glc.org/dailynews/20210119-ecological-monitoring-gull