Photo Credit: Emma Lee/for NewsWorks
This winter the Northeast Wastewater Treatment plant by the Betsy Ross Bridge has become home to a host of unexpected guests: southern cave swallows! While the plant has been a winter residence for a large population of northern rough-winged swallows since 2005, the arrival of their new companions has been baffling birders.
The rough-winged swallows of Northeast Philly are a highly unique group in the bird world. Typically seeking shelter from cold weather in the South, Philadelphia is the only northern city where the swallows stay throughout the winter months. Their relatives, cave swallows (typically found in Mexico), have also been moving north recently, which bird experts say is caused by climate change.
According to Anthony DiGironimo, the facility’s process manager, the reason for the birds’ extended northern vacation is food. Insects called flying midges are attracted to the large underground wastewater treatment pools. The pools maintain a constant temperature through the winter, making a safe home for the midges, which in turn provides the birds with a steady food supply.
However, there are alternate theories for the swallows’ behavior changes. Perhaps the birds use the waterway near the plant for navigation, or the plant could have a warm roosting spot. Regardless of their motivations, birders continue to enjoy observing these odd feathered friends.
Learn more about the swallows of Philly from Newsworks!