[CT Birds] Plankton feeding gulls

Dennis Varza dennisvz at optonline.net
Thu Mar 1 16:08:53 EST 2012

Some more on gull feeding

Many people have wondered about the efficiency of the gulls feeding  
on plankton. Here are some ideas.
When feeding the gulls sit on the water and the only energy involved  
is dipping the bill. I compare it to sitting on the couch eating  
sunflower seeds (I had a roommate that loved them). Compare that with  
Kinglets and Chickadees flitting about in winter feeding on scale  
insects. I am always amazed by the Chickadee that flies from the  
woods grabs a sunflower seed flies back to the woods open and eat the  
seeds and repeat.

If one wants to see the behavior at any time, go the Captains Cove  
Marina in Bridgeport. In the area of the Ice House with the fish  
painted on it is the outflow for the sewage treatment plant. There  
are always Ring-billed gulls feeding in there, sometimes Bonaparte's  
Gulls as well.

Concerning Slipper Shell Larvae.
Slipper Shells are Gastropods, they have a very different larvae  
(Trochophore)  than Barnacle  Cypris. (there are many other types of  
larvae) Also, the slipper shells generally reproduce later. One has  
to think of the different spawning seasons like the migration of  
different species.


The above web site covers a lot about Slipper Shells in the  
Nantucket/ Western Long Island area.
The species of barnacle here is Semibalanus balanoides
Back To gulls
If one pays attention to the three local gulls one would notice they  
are very different.
They have different roost site preference
They feed differently. Herring Gulls are bottom feeders when not  
looking for food in the rocky crevices of a bar or base of a bluff,  
they are out on the flats looking for clams. Ring-billeds on the  
other had are more top feeders looking for littile things on the  
surface. They frequent the flats at the water edge looking for little  
bits that get washed up. They naturally go for the little stuff. So  
it is natural that  they usually make up the bulk of the drifts of  

On Mar 1, 2012, at 1:06 PM, greg hanisek wrote:

> Since a couple of people have raised the possibility of the gulls  
> feeding on fish attracted to the plankton, I would add my own  
> observations. A number of us have been watching these  
> concentrations and feeding groups for a number of years. All the  
> birds participating - which include gulls, ducks and sometimes  
> brant - feed in a similar way. They daintily peck at the surface of  
> the water. I've never seen them raise their bills with something  
> visible in them. They feed in a manner very similar to accompanying  
> non-fish-eaters such as scaup and Gadwall. The gulls dip the tips  
> of their bills into the water as if taking items that are not  
> trying to elude them. There is none of the aggressive plunging,  
> grabbing and submerging that I would associate with taking fish.  
> This often happens when the water is very calm, so its easy to see  
> the method if not the prey. It's possible the concentrations of the  
> food items are so dense that this isn't a matter of picking
>  up a single tiny creature but numbers of them at one time.
> It's also worth noting that this is different from the feeding at  
> Hammo described by Keith Mueller. He got some terrific pictures  
> last year of the gulls with creatures in their bills that were easy  
> to see. I don't personally know anything about the Slippershell ID,  
> which Keith mentioned recently, but clearly those creatures were in  
> that size range. This was different from the surface feeding in the  
> wetsern end of the Sound.
> Greg Hanisek
> Waterbury
> --- On Thu, 3/1/12, paul cianfaglione <pgcianfaglione at gmail.com>  
> wrote:
> From: paul cianfaglione <pgcianfaglione at gmail.com>
> Subject: [CT Birds] Plankton feeding gulls
> To: "CT Lists" <ctbirds at lists.ctbirding.org>
> Date: Thursday, March 1, 2012, 11:48 AM
> I really enjoyed the discussion about plankton feeding gulls. At  
> first, I
> had a hard time wrapping my mind around the idea of gulls with  
> large bills
> feeding on microscopic organisms. But after reading about Herring Gull
> feeding habits, I guess it is certainly something to consider.  
> Below is a
> small excerpt from The Birds Of North America Online regarding  
> Herring Gull
> feeding habits;
> *At sea, forages in large, widely scattered groups that coalesce  
> quickly
> through rapid recruitment when prey concentrations located  
> (**Hoffman et
> al. 1981*<http://bna.birds.cornell.edu/bna/species/124/articles/ 
> species/124/biblio/bib061>
> *, **Pierotti 1988*<http://bna.birds.cornell.edu/bna/species/124/ 
> articles/species/124/biblio/bib099>
> *). Often follows foraging humpback whales (Megaptera novaeangliae) or
> groups of delphinids. Hovers over feeding groups grabbing fish, squid,
> zooplankton concentrated at surface by mammals, diving birds, or large
> predatory fishes swimming underneath concentration (**Pierotti
> 1988*<http://bna.birds.cornell.edu/bna/species/124/articles/species/ 
> 124/biblio/bib099>
> *).*
> I understand that gulls may shift foraging patterns to take  
> advantage of
> short-term fluctuations in food supply. It just seems inefficient  
> for gulls
> to feed on microscopic plankton unless they are taking in massive  
> amounts
> at a time.
> As an alternative thought, could gulls that attend plankton  
> concentrations
> be feeding on other prey items?? Many types of fry fish feed on  
> plankton.
> What may appear to be plankton feeding,  could in fact be  
> opportunistic fry
> fish feeding.
> Paul Cianfaglione
> Canton
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