Delighted to observe a perched Peregrine Falcon while driving in Woburn this morning.
It was preening itself in the warm morning sun. Watched it for about 20 minutes before it finally launched into flight in my direction and then passed by out of sight. Photos revealed color-coded leg bands, so we will hopefully be able to be updated further on the location of where this falcon was banded!

UPDATE:

With great credit to Tom French and the staff at MassWildlife, they were able to track down background information on the black/green color-coded leg bands on this young Peregrine.

This young, female Peregrine was banded in June 2014 on a bridge in Northampton, MA (Hampshire County). More information on the bi-color, field-readable, alphanumeric leg bands posted below.

From the Center for Conservation Biology website:

Peregrine Falcons are fitted with metal leg bands to provide researchers with valuable data on peregrine survival rates, dispersal distances, and population growth rates.
The standard leg band for Peregrines is a silver metal band issued by the federal Bird Banding Lab. The band is inscribed with a unique 9 digit code that allows birds to be identified during future resights or captures. To report seeing one of these bands, visit the ReportBand.gov website.
A second bi-color band is fitted on the falcon’s opposite leg and includes a field-readable alpha-numeric code. Falcons in the Eastern US are banded with either BLACK over RED (1989-2004) or BLACK over GREEN (2000 – present). There are also several orientations and alphanumeric character arrangements on the bands.

When reading a band, an observer should note the top character and its orientation (vertical or horizontal), the top background color, then note the bottom character code, orientation, and color.