The caption says it all. The image links to the photographer's Flickr page.
Douglass estimated -- or guesstimated -- his birthday to be in February. There is no documentation for this, and he, in fact, also guesstimated his birth year to have been 1817 when documentation has shown he was born in 1818. Of course, this was one of his point in his autobiographies. He did not know when he was born, nor did any other slaves, because the system of slavery was designed to keep slaves ignorant of everything, including the circumstances of their own births. Like many other features of his life, the date of his birth became part of Douglass's self-invention. He claimed a name, an education, a career, the right to formulate his own ideas, his freedom, and his own date of birth. As he portrayed himself, he symbolically gave birth to himself.
"As he portrayed himself": What really happened? Well, that's where things get interesting!