North Atlantic right whale, calving
Later in the yearNovember 15 to April 15
“From Nov. 15 to April 15, pregnant females migrate from their northern feeding grounds to the sheltered waters of the calving ground to give birth to their young.”
Florida Fish and Wildlife Conservation Commission
A second FWC page gives "approximately December through March" for the same event. NOAA's wording, "begins in mid-November and runs through mid-April", is the one we follow, and the federal speed restriction over the calving area uses exactly November 15 to April 15.
What you are looking for: No dorsal fin at all, a broad black back, a V shaped blow from two separated blowholes, and rough white callosity patches on the head. If you think you have seen one, NOAA runs sighting hotlines: (866) 755-6622 from Maine to Virginia, (877) 942-5343 from North Carolina to Florida.




