Article by: Aaron Coolman, Will Krohn, and Blake Goll | Video by: Julia Griffin
ft. Farmer Bob Lange of Sugartown Strawberries
Purple Martins, the largest swallows in North America, are more than just a beautiful sight in summer skies; they are an essential part of our ecosystem and a Species of Greatest Conservation Need in Pennsylvania. These aerial insectivores spend their summers breeding across much of North America. Their eastern nesting range consists almost exclusively of manmade housing colonies.
Have you ever noticed a tall pole with dried gourds hanging from it? These are the communal nesting sites for Purple Martins (Figure 1). The design mimics lost breeding habitat from the landscape (i.e. abundant tree cavities). In late summer, martins gather in enormous roosts before making their long journey to South America for the winter.
Despite their prevalence in rural landscapes, Purple Martin populations are declining across much of their range. Loss of nesting habitat, decline of insect populations, and shifting climate patterns are all potential contributing factors to their decline. Invasive species, like European Starlings and House Sparrows, can outcompete martins for their nesting sites. Because martins in eastern North America now rely almost entirely on human-constructed nest sites, their survival is closely tied to the care and stewardship of people who maintain their colonies, lovingly dubbed “Purple Martin landlords.”
Banding and monitoring Purple Martins is a key conservation tool. By banding individual birds, researchers can track trends in population, demographics, and the connection between breeding colonies. This data helps guide conservation efforts to protect these birds well into the future.
Will Krohn, bird bander and wildlife ecology Master’s student at the University of Delaware (Figure 3), is tracking how Purple Martins move between nesting colonies. This process (called natal dispersal) is a key aspect in the survival of the species. Although it largely remains a mystery for this enigmatic bird. Using a coded system of colored leg bands attached to the chicks (Figure 2), the color combinations allow researchers and the public to uniquely identify the breeding colony where each bird was hatched. If you see a color-banded Purple Martin, you can submit it to an ongoing citizen science project.
Want to see Purple Martins in person? Look for colonies in open areas, farms, or near wetlands. Communities in these habitats often host thriving populations of Purple Martins thanks to the diligent efforts of martin landlords. Visit a colony in June or July and you’ll likely see adults delivering insects to their young or adding materials to their nests. Listen for their song: a rich series of gurgling whistles they make while perched or flying. For our early-risers, you may be lucky to hear the Purple Martin “dawn song”- a song performed by the adult males to attract new martins into their colony. Even if you aren’t near a Purple Martin colony, you may see them flying high and catching insects over agricultural fields, meadows, or wetland habitats. Conserving these open landscapes is crucial in giving Purple Martins, among many other species, a place to call home. By providing habitat and monitoring these birds, we can ensure that future generations get to enjoy the dazzling sight of Purple Martins swooping through summer skies. To become more involved with WCT and our bird banding program, check out our Bird Conservation web page.
*Wild birds are handled under federal and state permits for research purposes
