Four Herons

Herons, a set on Flickr.

Boston’s “Other Emerald Necklace”?

In June and July and August, volunteers reported four species of herons at Fresh Pond’s Black’s Nook: Great Blue Heron, Great Egret, Green Heron (at least six individuals), and Black-crowned Night Heron (at least four, including two juveniles). Green Herons have been present since May, and with the late-summer appearance of juveniles we seem to have collected good evidence that they have probably nested successfully at the site or nearby. Black-crowned Night Herons were reliably present in July, but may well have arrived from another nesting colony.

It’s interesting to look at this cluster of herons at Fresh Pond in a larger geographic context. 

The following maps show sightings from the eBird database of all four species in 2012 (as of mid July) and over the past 10 years or so.  Here’s one species as an example:

Black-crowned Night Heron, 2012 (as of mid July)

Black-crowned Night Heron, all years in eBird (mainly last ten):

Within the mapped area (approximately 10 x 15 miles) and outside the banks of the Charles and Mystic Rivers, Black-crowned Night Herons seem to be concentrated along a long north-south corridor of green, wet spaces, including Black’s Nook.  The corridor extends from the Middlesex Fells through Upper and Lower Mystic Lakes, Arlington, Alewife, Fresh Pond, and Mt. Auburn Cemetery to the Charles River.  (Cont.)