Coastal Waterbirds & A Mystery Booby

 

From the beginning of the month large numbers of Sandwich Terns have been gathering along the coast, feeding in Marco Inlet and roosting on the south end of Sand Dollar spit. This is a usual fall phenomenon; actually, these terns are only in the area in any numbers during the fall and early winter when they are coming south to winter in Central and northern South America (a few are present all year). Interestingly, little is known about their northern migration except that it appears to be much quicker (they arrive April in NJ almost en mass). Here in spring we hardly see any.

On November 9 while censusing the area, I recorded over 10,000 coastal waterbirds in the Marco Inlet; most were Sandwich Terns but there were over a thousand Laughing Gulls and roughly 500 Brown Pelicans. I call this an incursion; which I define as a large influx of coastal waterbirds occurring in the region for a limited amount of time. Most incursions (but not all, some happen for no apparent reason) are associated with good numbers of bait fish and this one was no exception. Mackerel, Pompano and Jacks (all fast swimming fish that pray on bait) were having a ball and driving the bait to the surface which made the bait available to the birds. What a lot of fun.

On November 12, I censused south of Marco and although there were a lot of Sandwich Terns and plenty of shorebirds (9,339 spread along 20 miles of outer coast), the highlight of the trip was one mystery bird. The photo shows a Booby that was on a sandbar at Cape Romano seven miles south of Marco. The problem is that I can not find any Booby in the field guides that match this one. It has the adult plumage of either a Masked or Red-footed Booby; the bill is the color of a Red-footed, dark-gray but the legs and feet are dark-gray (any other color than dark-gray you see in the photo is from the digital printing) with not a hint of red which all age classes of Red-footed are shown with. The books show Masked Booby s with dark gray legs and a yellow bill but this bill is dark gray. In the field guides the Masked Booby has a yellow iris and although hard to see the photo the yellow iris is visible. One guide says that Red-footed have a white tail and the photo shows a black tail, then this should be a Masked but another book states that one morph of the Red-footed has a black tail. So is this a Masked Booby with a dark bill and a yellow iris or is possibly a hybrid (one account mentions hybridization). I am going to call it a Masked Booby and let it go at that. If some of you want to look in more books, I ll bet you can make it more confusing, or maybe you know. If so, please let me in on the secret.

Ted Below

First published on the Collier County Audubon Society's web page in November, 2004