Wednesday, February 29, 2012

Plankton feeding time for gulls

As we enter March we also move into a month known to many birders for its gull feeding extravaganza. Up to tens of thousands of gulls can be seen feasting on plankton in western Long Island Sound in the next few weeks, especially around the full moon. I referenced this phenomenon in the information about our next Stratford Point bird walk at a time when thousands of gulls could be resting on sandbars in the mouth of the Housatonic River.

The food source involved in this feeding frenzy has been debated for some time, though intelligent and intrepid birders have come to somewhat of a consensus in that the meal of choice is almost entirely barnacle larvae. A few have collected samples of what the gulls were eating. Last year Charlie Barnard brought samples to our own CAS Conservation Biologist Twan Leenders who took a look at it and passed it on to other scientists. Here are a couple of shots Twan had taken...

There was, as usual, some debate, though our belief is still that these are barnacles in the cyprid stage. Others, including Dennis Varza, Larry Flynn, and John Barclay have done a tremendous amount of work in collecting samples and researching this, coming up with that conclusion. All credit goes to these great birders with inquisitive minds and commendable efforts. If an expert in the field has anything they would like to contribute we would love to hear it.

Scott Kruitbosch
Conservation Technician

Photos © Twan Leenders

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