By Brian Harrington
If you are attuned to birds in our watershed you probably know the Tree Swallow well; it is among the earliest of our spring migrants, sometimes arriving before the end of March, and quickly spreading across the continent, even to Alaska. They adopt nest boxes and tree holes as nesting places and lay anywhere from a few to half a dozen eggs. Here in our watershed they grace the airways over our meadows, lawns and lakes throughout the summer, swooping and dodging to catch flying insects. They can be joined by newly fledged young before the end of June, and some are beginning southward migration before the end of July.
Now, in September, huge flocks of tree swallows from the northeast are gathering, sometimes in swarms of thousands, and typically at or near Atlantic coastal locations where their largely insect diet begins to include berries, and especially bayberries. Meanwhile, their brethren from Alaska and the Canadian Prairies are gathering and moving southward along regions of the Upper and Lower Mississippi river basin. Major wintering areas are on coastal plains of US southeastern states (especially Florida and Texas), the California Central Valley, in Yucatan and western Mexico, and in Cuba.
During our spring and summer we can often find blue and orange Barn Swallows hunting insects virtually side-by-side with the blue and white Tree Swallows. Although they might have similar habits whilst here, they have a dramatically different migration, with some travelling as far as the fields and wetlands of the Argentine pampas, about 5000 miles farther south of the Tree Swallow wintering latitudes. This is among the longest migrations of any North American landbird.
Alas, most of the Tree and Barn Swallows will be gone from our watershed before the end of September, leaving us to look forward to their return next spring.