There is a Law Against Frightening Pigeons in Massachusetts
At best, most people are fairly indifferent to pigeons. They're incredibly common and there are two primary types found in New England.
There's the iconic Rock Pigeon known for the pretty green and purple on their neck as well as the Mourning Dove, which despite being called a dove is in the same family as the Rock Pigeon called Columbidae.
Massachusetts has a special protection for pigeons from 1848 that can be found under Part IV, Chapter 266, Section 132 it reads;
Whoever wilfully kills pigeons upon, or frightens them from, beds which have been made for the purpose of taking them in nets, by any method, within one hundred rods of the same, except on land lawfully occupied by himself, shall be punished by imprisonment for not more than one month or by a fine of not more than twenty dollars, and shall also be liable for the actual damages to the owner or occupant of such beds.
So no, you won't be fined $20 if you startle a pigeon outside Fenway Park or if your kiddo runs toward a flock of them chilling outside of Faneuil Hall sending them flying.
This law doesn't appear to be a law regarding protecting the birds, but instead to protect hunters. From an article from BU, this law made sense for the time as many people would hunt and eat pigeons as well as use them for target practice. BU goes on to say that more modern laws prohibiting people from interfering or obstructing hunters largely make the old law irrelevant.