I have been seaduck hunting the Downeast coast for 30 years and have only seen- for sure- 2 sets of Brant. Very uncommon for us to see these birds and noteworthy when we do. Hope to see more, but wouldn't really know how to hunt them. Never bagged one, and don't know anyone who has.
Hutch
Hutch: They are pretty common in Kettle Cove and off Crescent Beach State Park, both in Cape Elizabeth. I think they see then down in Saco Bay, too.
I don't keep a bird log or anything, but would say that seeing them there in mid-winter is common but not an everyday occurrence. I remember them a time or two when I was a kid, and see them most winters now when I go down to visit my mom. But I don't think I've ever seen a flock of 40--usually just a handful. I took my son and his buddy surfing at Higgins last October and saw a huge flock flying north. You may recall Troy posted pics here the next day of some surprise brant he found- same flock probably. I was at Higgins again in early May and there was another big flock working the outer islands and rock piles. Hi Hutch!