The birds that we see flocking up and forming a murmation over Gloucester’s downtown skyline are typically European Starlings, a species that was introduced to the U.S. from Europe at the turn of the previous century. The birds that are in the film that I posted yesterday, Dance of the Swallows, are Tree Swallows. They prefer more remote areas such as sand dunes, where the swallows find a wealth of insects.
Insects comprise the bulk of their diet. Tree Swallows perch on branches, telephone wires, and in our area, commonly on Northern Bayberry (Myrica pensylvanica) and other dune shrubs. Most birds cannot digest the waxy coating on Bayberries, but Tree Swallows are one of the few species that can. Bayberry fruits do not ripen until September and I wonder if when migrating through Cape Ann in August, the Tree Swallows are eating the insects on and around the plants, not the unripened fruits.