Rosita Corey was a Massachusetts schoolteacher who recorded spring bird arrivals for decades; her old notes now help show that some birds are arriving about 7 days earlier

A notebook kept by a Massachusetts schoolteacher is now part of a long record showing how spring bird migration is changing. Rosita Corey, a retired schoolteacher and birdwatcher in Concord, Massachusetts, maintained records of first arrival dates of birds from 1956 to 1973 and again from 1988 to 2007. Researchers combined her observations with older records and, more recently, modern bird sightings to study changes in migration timing. A 2025 study, "Integrating historical records and citizen science data to understand bird responses to climate change in Concord, Massachusetts: Thoreau to eBird", found that 18 migratory bird species were arriving in Concord approximately seven days earlier, on average, in the modern period than in the historical records.

It started with observations made more than 170 years ago