I pulled up to a rather crowded beach with a few of them even being birders. I decided to sit on the bench for a while facing the SS Atlantus and just scan the water with my bin's to see what I could find. Usually one sees their share of cormorants in a 'line-up' on board the ship but they must have all found warmer waters by this time of the year. A nice birding couple from Cape May sat next to as we all gazed at the gulls in the water. It was rumored that there was a black-headed gull to be seen and we surely saw 5-6 'winter' gulls with a black dot behind their eye. So the question that pondered me which immediately had me pull out my iPhone with the iBird Pro app was, what is the difference between a 'wintering' Black-headed gull and the Bonaparte's?
According to iBird.... wintering Blacked-headed gull:
"has a black spot behind eye"
According to IBird....a wintering Bonaparte's gull:
has dark spot behind eye'
Hmmmmm....sounds like birding the tropics as one has to decipher between a 'dark spot' and a 'black spot'....as they float in waves, ..up and down, up and down.
There are a couple of other differences too such as the Black-headed has a dark red beak while the Bonaparte's gull has a black beak. Well, we all know how that goes as a dark red beak looks like a black beak unless caught in the right angle to the sun. Another difference observed 'in flight' would be that a Bonaparte's has black wing tips and is more pale under primaries.
For a moment I really thought...I really thought that one of the birds had a bit of red in the beak. I saw it....the couple next to me didn't. So I decided to get my hiney off the bench and walk closer to the rocks jutting out.
I stopped....pulled my bin's up and gazed once more at any beak I could find. They all appeared at this moment to be black so, heck...might as well wait it out and see them in flight as for some odd reason, they get it into them that the 'floating' is better a few meters up the surf line. One by one over the course of a few minutes they would take flight for a few meters and each time, ....no, no Black-headed....all Bonaparte's. Oh well....5 Bonaparte's, or was that 6, or perhaps 5 Bonaparte's and 1 Black-headed hiding from me.
So overall---a nice sunny day watching seagull behavior.