Like many other aerial insectivorous birds, Tree Swallows are declining throughout their northeastern breeding range. While still widespread in Maine, Breeding Bird Survey data indicate Tree Swallow populations declined by ≈88% between 1966 and 2019. Because of this, they are designated as a Species of Special Concern and Priority 2 Species of Greatest Conservation Need in Maine. Reduced insect availability, habitat change, contaminant exposure, and shifting climate conditions are all likely factors in this decline.
Volunteer Resources
MNHO is not accepting volunteers Tree Swallow nest box monitoring at this time.
Tree Swallow nest boxes are vulnerable to extreme heat due to their exposed nature. Heat stress may negatively impact swallow breeding attempts, particularly during extreme weather events. Beginning in 2026, MNHO staff and volunteers will be testing a modified nest box design, which incorporates a wider floor plan to permit increased airflow and the addition of a PVC heat shield to mitigate heat and reduce nesting failure due to extreme weather.
Nest box plans and additional project resources for volunteers may be made available following the 2026 field season.
Click the links below to view the nest box monitoring data sheet and handbook:
Project Collaborators
Maine Aerial Insectivore Monitoring and Stewardship Initiative (Maine AIMS)
Project Supporters
Maine Department of Corrections
This project is made possible by the many
landowners and property managers who support our work by deploying and monitoring nest boxes on their properties.
Thank you!
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