Name That Bird.
What is it?
It is strange-looking!
It's a gull, of course. It is a first year Great Black-backed Gull. You may know that gulls do not mature for two, three, or even four years (like eagles), and that their plumage is very different depending on their age. Initially, I knew this was a Great Black-backed Gull because of it's large size compared to the Herring Gull. I've since verified that this is indeed the markings of a first year GBBG.
You probably already know how to identify the three most common adult gulls in Massachusetts. The Great Black-backed Gull is easy. It is by far the biggest gull there is, it is the only gull with a jet black mantle as an adult, it has decidedly pinkish legs and feet, and it's bill is marked with a round red spot.
The Herring Gull is the most common gull seen in Massachusetts. Adults have pale grey mantles, black tipped wings, a red spot on the bill, and pinkish legs. In the winter their heads are often streaked with brown.
The Ring-billed Gull is smaller than a Herring Gull, but similarly colored. Non-breeding adults and juveniles have streaky heads, and their bills are ringed with black at the end. Ring-billed Gulls are three-year gulls, while Herring Gulls and Great Black-backed gulls are four-year gulls. They look totally different during each of the first three or four years of their lives.
Sometimes a gull that is normally identified by the red spot on it's beak will have a black beak one year and a black tipped beak another year. Such is the case with GBBGs. At three years old, it has a speckled mantle and a beak similar to the Ring-billed Gull.
All the mystery birds I saw on South Beach are almost certainly juvenile gulls.
I have no idea what kind of gull they are, though. After hours of research, I had to give up. My pictures are too blurry to match with anything. I really saw nothing resembling these birds anywhere. But there are many species of gulls, and many varieties within a species. I didn't even mention the Laughing Gull today, although they are also fairly common on the coast. I wouldn't recognize an immature one, though.
Maybe you've seen one of these before?