What happened to Pitch Swamp on Route 121?
If you’ve driven through the intersection of Routes 121 and 137 in Bedford, you’ve seen it: the forested swamp on the southeast corner has become open marsh. Trees have died en masse, some toppling, some still standing as snags. What you might not have noticed is that great blue herons moved in, taking advantage of the dead trees and establishing a rookery.
But why the trees died is a mystery. Beth Evans, a wetlands scientist and the Town of Bedford’s environmental consultant, suggested that it might have been a blight or an increase in the swamp’s water level, which would have drowned them.
She analyzed Google Earth images and saw that the change started in spring 2009 and that by summer 2011 the trees were dead. She saw no evidence for either of two theories: that a beaver dam or blocked drainage culvert had flooded the swamp.
The rookery has about ten active nests and dozens of great blue herons, four-and-one-half-feet tall, almost prehistoric looking: the only such rookery in Westchester.
Pitch Swamp is private, flooded, and ringed with poison ivy; herons abandon nests if people get too close.