[CT Birds] Barnacles-a-commin

Dennis Varza dennisvz at optonline.net
Wed Feb 29 10:07:21 EST 2012

Hi Folks

Here is the general overview of the Phenomenal phenomenon

When the Phenomenon occurs one will see thousand of gulls sitting on  
the water feeding heavily. The birds are pecking at the water. They  
are not diving as for fish. Although most of the gulls are Herring  
and Ring-billed, all other regular species have been found at one  
time or another. Although, Great-Black-backed Gulls don't seem to  
participate much. In addition to Gulls one can see Brant, Scaup and  
the puddle ducks, including Blue-winged Teal and Northern Shovelers.  
The mix of species depends upon the time of the year.

The phenomenon has been observed since the turn of the century. I  
don't recall it occurring in the 80's

Due to Geology, rocky coast and narrow Sound, the phenomenon  is  
confined to wester Connecticut, nowhere else on the east coast (as  
far as I can tell from communications). The same species of Barnacle  
is found and europe and it is know to have synchronized reproduction  
over there. The western most observation I have of them is the  
Norwalk Islands, but I suspect that it could be found in Stamford.  
The eastern most observation I have is Morningside in Milford, But, I  
imagine it could be occurring off New Haven Harbor and perhaps the  
Thimble Islands.

I have seen it occur any time from late February to early May over  
the years. Full and new moons increase the probability of it  
occurring but we have seen it at other times, particularly in heavy  
years. Some years it has been spotty with patches here and there.  
Other years it has been intense. and thousands of birds could be seen  
feeding on them from horizon to horizon.

The weather makes a difference in the availability of the larvae to  
the birds. For organisms as small as the larvae water is more like  
molasses. Wind and wave action are more important in dispersal that  
actual swimming. During days of low wind, the water becomes flat and  
traps the larvae at the surface. That is when big flocks of birds are  

I tried communicating with people at the marine lab at Avery Pt. At  
first they were attempting to be helpful. When I told them about the  
part about gulls feeding on them, they did not believe it and thought  
I was seeing the birds going after fish feeding on the larvae. They  
soon lost interest.

Conclusions: The synchronized reproduction of the Barnacles is an  
annual event. The actual mechanism has yet to be determined and needs  
a study of the barnacles themselves. But, the combination of time of  
year and weather conditions determine how available the larvae are to  
the birds.

Dennis Varza

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