Long Island Sound Barnacle Larvae Gull Feeding Blitz

Discussion form CT Birds Listerv-

    With the recent discussion on the CT Birds Listserv regarding the upcoming Gull (plankton/barnacle larvae) feeding blitz that will occur in the western half of the Sound, I thought it would make a good report. This has turned out to be a very interesting and informative discussion, and for those who have never experienced this feeding bonanza in late february/early March, I have included some images from last spring. The images were taken in Bridgeport, Fairfied, Stratford and Madison. I posted the images throughout the text and below the discussion.


From Ron Ashford:

James O'Donnell, an oceanographer at the University of Connecticut is preparing a summary

article about LIS water temperature.  I believe he is submitting that to the Long Island Sound Study.  The Millstone temperature record is too short to comment on trends for there are some long-term natural cycles that are influencing water temperature in addition to global warming.  Jim has the temperature record from the former Noank Marine Lab (~1960's to ~1990) and recent discovered the Milford Harbor data collected by the National Marine Fisheries Service (late 1940's to the present). 

NERACOOS is working to create climate graphs for all the northeast ocean observation sites 

and its LIS partner LISICOS has create the first climate graph for dissolved oxygen http://lisicos.uconn.edu/clim.php .  While the buoy data records are only ~10 years in length, these graphs show the average, the variance and also the current conditions.  LISICOS is working on an interactive graph.  NERACOOS hopes to roll out climate graphs by next summer. 

 From Scott Kruitbosch:

     Twan and I discussed this on Friday actually before the discussion on the 

list in picking out a date. We're all thinking the same thing. See if you can come down for this evening and maybe peak-time gull event...Connecticut Audubon Society Conservation Technician Scott Kruitbosch will lead a public bird walk at Stratford Point on March 8 from 4 p.m. to sunset with an inclement weather date of March 9, same place and time. It will be a great chance to find some migrant waterfowl and new ducks for the season, a handful of newly arrived shorebirds and long-legged waders, and to see possibly thousands of gulls in the mouth of the Housatonic River at low tide. March 8 is the date of the full moon when there should be a great number of barnacle/plankton blooms on the waters of Long Island Sound, bringing in gulls to feed on them that will then rest on the sandbars between Stratford Point and the Coastal Center at Milford Point at low tide. Two years ago, a similar event saw upwards of 10,000 gulls present here. While numbers that day may not surpass that total, it is a good bet that we will have a bunch of birds to see.

We will also discuss the conservation projects that Connecticut Audubon Society will be involved 

with in the coming spring and summer. The walk will be free and we suggest bringing binoculars and a spotting scope, if you have one. This is especially needed to help identify the many gulls we may be looking through. Make sure to dress for the season! It is usually safe to assume that this exposed coastal spot is windier and colder than much of the state. Please meet in the visitor parking lot by the buildings. Stratford Point is located at

========

Scott Kruitbosch

Conservation Technician

Connecticut Audubon Society

2325 Burr St.

Fairfield, CT 06824

CAS blog: ctaudubon.blogspot.com

CAS Twitter: twitter.com/CTAudubon

Email: skruitbosch at ctaudubon.org

www.ctaudubon.org

 From Frank Mantlik:

     2/29  Stratford, Lordship Seawall & Long Beach. I popped out briefly 10:30 to view 

LI Sound before the rain/winter storm began.  I discovered several hundred gulls sitting on the water, plankton-feeding, just off the Lordship Seawall at Marnick's Restaurant.  Among them was an adult LESSER BLACK-BACKED GULL.  I called a couple local birders. The wind blew the

gull flock (& plankton?) west towards Long Beach. I was joined at Long Beach by Charlie Barnard,

where I estimated 1000 gulls (60% Ring-billed, 40% Herring), including the LBBG and 1 Bonaparte's.  By 11:30 the flock had dispersed somewhat, as well as was blown much farther offshore towards Bridgeport.  Then the rain began.

Frank Mantlik

Stratford

  From Frank Mantlik, with Charlie Barnard

2/29 Stratford, Long Beach - Adult LESSER BLACK-BACKED GULL, 1 Bonaparte's Gull 

with 1000 gulls (60%/40% Ringbilled: Herring) plankton-feeding.  Also numbers of 

Brant, Black Ducks, Common Goldeneyes, and Long-tailed Ducks.

        Penfield Reef- part of the morning Gull roost at low tide-

    Bonaparte's Gulls start arriving.......

    .....and start surface-feeding.

    Surface-feeding Ring-billed Gulls.

     Two Lesser Black-backed Gulls on the reef that day.

 From Bill Yule: 

  Re: the gull feeding behavior...

I have seen this behavior in the CT River in Essex in both the Spring and the Fall.

I have posted about this before here but still the question seems unanswered "What are they 

feeding on?" Dennis says Barnacle larvae, Frank says plankton, someone else fish but how do we know these things? I'm curious has anyone ever dragged a plankton trawl through these gull flocks and ID-ed the food source or are the previous comments educated guesses?

Any references anyone could supply would be appreciated. Is it possible Blue Crab larvae 

are involved? I ask because it seems to me Plankton blooms are something different from synchronomous larval hatches and it would be interesting to know if it's one or the other or both of these events.

 From Keith Mueller:

     I ran into Frank a couple of times last March at Long Beach and the seawall when 

this feeding activity (or frenzy would be a more accurate way to describe it) was happening. There were an estimated  (conservative estimate) of 10,000 Gulls to a more realistic estimate 

of 25,000 Gulls caught up in this feeding blitz. There were also high  

numbers of Bonaparte's Gulls, Brant, Scaup and Black Ducks mixed with  

the Gulls. He also located several GLaucous, Iceland and Black-headed  

Gulls. But it was obvious; whatever they were feeding on was floating  

on or just below the surface of the water. I know Dennis, Larry Flynn  

and Nick were out collecting the organisms that the Gulls were feeding  

on (look at Dennis' earlier post).

This activity was also happening off Short Beach (with nearly 750  

Bonaparte's Gulls one morning near the beach), Penfield Reef and  

outside Fairweather Island in Bridgeport. Like Frank I also found a  

few other Gulls: 1 Glaucous, 2 Iceland, 2 Lesser Black-backed, 1  

Black-headed and a very possible Slaty-backed GUll all exhibiting the  

same surface-feeding behavior.

However in early March last spring large flocks of Bonaparte's Gulls  

were in close to shore at Hammonasset. The wind was strong east and  

the birds were tucked in close to shore at the beginning of the  

Moraine Trail near the large boulders and crashing waves. The birds  

were feeding heavily on whatever was drifting just below the waters  

surface. I photographed the birds that were very close to me. In  

reviewing the images in my camera I could see the birds holding what  

appeared to be small fleshy colored leech-like creatures about the  

size of stretched soy bean. I walked near the edge where the waves  

were crashing and these leech-like creatures were wiggling in the  

water being pushed by the waves. I grabbed a few to look at and  

realized I was looking at the fleshy creature inside slipper shells.  

Not sure if this is a naturally occuring event in mating or the  

creature has left or forced out of its shells. Maybe someone who knows  

can comment.

So it looks like these Gulls are feeding on a varied array of food items.

Keith Mueller Killingworth

From Hammonasset- Bonaparte's Gulls feeding on Slipper Shell flesh-

 From Charlie Barnard Jr.:

     In answer to Bill Yule's questioning about the type of plankton upon which

the birds are feeding: the zooplankton (it swims) has been collected

numerous times from many locations and it is, almost without any doubt at

all, almost entirely barnacle plankton.   I know that Dennis Varza and

Dr.Jack Barclay have pulled plankton nets behind Larry Flynn's boat (thank

you to all of them) from Norwalk east to about the Bridgeport/Stratford

town lines. They were far enough offshore to be right in the feeding

lanes of the gulls and they identified the plankton as being composed of

barnacle larvae.  I will leave it to Dennis, Larry and perhaps Dr.Barclay

to confirm the results.

I tried unsuccessfully to get the Bridgeport School of Aquaculture out

there to collect samples. The instructor with whom I met had no idea of

what was taking place. At least she was interested in finding out and

helping,   but she and some of her class were about to leave for a fish

aquaculture meeting in China. I never got around to talking with her again

after she returned. My fault on that one.

Anyway, I wound up collecting samples nearer inshore, from the end of

jettys where gulls were feeding and sometimes right along the shoreline

itself. I took the living zooplankton to Twan Leenders at the CT.Audubon

location at Stratford Point and Twan passed it on for analysis. There was

some disagreement as to what the plankton was in the samples which I took,

with some people (with a minimum of a Master's degree in marine sciences)

feeling that the plankton was mostly something called an ostracod. Others

never even looked at the samples to the best of my memory.

  Here is a link to a good book on the subject. I think that you can read

through quite a few sections online. Click on the photo gallery section and

scroll down to the "copepods and lower crustaceans" subsection. Both

ostracod and barnacle cyprid larva are pictured. For what it is worth (and

it shouldn't be worth much) I agree with those who identified the larva as

barnacle larva.  I studied the book photographs and looked at the samples

under a microscope myself, thanks to Twan having brought his own microscope

to Stratford Point.

http://www.zooplankton-online.net/index.html

"Zooplankton of the Atlantic and Gulf Coasts: A Guide to Their

Identification and Ecology." It is by William S Johnson and Dennis M Allen.

Incidentally, quite a few years ago, a group of us saw feeding gulls in

multiple lines stretching from Russian Beach in Stratford all the way to

the vicinity of Penfield Reef Lighthouse in Fairfield - as far as we could

see with scopes set up.  Each line contained thousands of gulls and we

estimated well over 50,000 birds.  There were most likely more birds to the

west of our view, so 50,000 was probably a very low estimate.

Charlie Barnard Jr.

Stratford

     If anyone is interested, here's  link to a photo of a sample I collected off of Stamford in March 

2009. We pulled a plankton net right through a flock of dip feeding gulls and brant. We measured about 2000+ specimens per cubic meter and they were all this animal, which we (non-experts) identified as the cyprid stage of barnacle. In addition to these, we had a very small number of segmented worm larvae.

http://bit.ly/wlMvTF

    One of two Iceland Gulls on the reef at the southern end of Fairwether Island.

From Dennis Varza:

     In response to recent e-mails

One can see this event anywhere from Milford to Norwalk where one can  

get a good view.

Stratford Pt.

Stratford Sea Wall

Stratford Long Beach

Bridgeport Seaside Park

Bridgeport St. Mary's

Fairfield, Penfield Reef

Westport, Burying Hill Beach

Westport Sherwood Is. St. Pk.

Westport Compo Beach

Norwalk Calf Pasture Beach.

Jerry Connolly reported seeing Gulls and Terns feeding off the  

eastern sound of fish larvae.

That is a different phenomenon. It is later in the season and include  

Terns and fish larvae.

The barnacles are usually done before the terns show up.

What to call the "Food"

Plankton refers to any small organism that floats in the water column  

not swim through it.

Phyoplankton are the plankton that are green. When looking at buoy  

data there is a reading of Chlorophyl -A and that gives an estimate  

of the amount of Phytoplankton It generally goes up in the spring  

with the increase in sunlight. and the increase in nutrients from the  

bottom.

The use of the word Bloom implies a refrence to Phytoplankton. This  

may have an effect on the Barnacle Larvae.

Zoplankton are the animal part of the plankton. It can be anything  

form fish larvae, crustacean larvae, worm larvae and assorted  

multicellular organisms.

Then there is micro plankton. Plankton nets have a certain mesh size  

which determine what gets caught or not. At some point they found  

that using a finer net got them a lot more organisms then they  

thought  was there.

Larvae are immature forms of organisms that are generally different  

in morphology than the adults. ie. insect larvae, Frog larvae, Fish  

larvae, Crustacean larvae. often time taxonomic identity is best done  

by looking at the larvae. At one time Barnacles were considered  

mollusks.

Could organisms other than barnacles be involves? Definitely, but it  

would most likely be other places at other times. Blue Crabs? I can't  

imagine crabs producing enough larvae to produce a drift of gulls  

several miles long.

Over the past couple of years Larry Flynn John Barclay and myself  

have been out on Larry's boat with nets and sampled the waters where  

the gulls fed. Every time Barnacle Larvae. John has said that when he  

was working on Greater Scaup, specimens would have their bellies full  

of the larvae.

Barnacles go through several stages. the eggs hatch into a feeding  

stage called the Nauplius After 6 months it transform into the Cyprid  

stage. This is the stage being fed on. It look like tiny clams with  

eyes and antenna, it does not feed and eventually attaches to a hard  

surface. Towards the end of the event one will see the gull along the  

rocky areas where the larvae settle out. The gulls will be scraping  

the rocks with the side of their bills trying to get at them.

This is another case of Birders know one thing Marine Biologists Know  

other things but little interaction takes place.

Dennis Varza

Fairfield

From Donna Caporaso:

         I find the current discussion fascinating anddecided to see what information is available 

on the internet regarding SlipperShells which were mentioned in a post and are abundant along our coast. And, anyone who has been to Long Beach in Stratford will know that the Gulls and Sanderlings  feast on the Slipper Shells all the time.  To feast on them sans shell would certainly send them into a frenzy. I remember hearing somewhere that when the eggs hatch it could beseveral weeks before they develop shells. Some of the info below relates to studies in Chili but is certainly speciesrelevant.

Here is just a snippet of info.  More research into when they Embroys hatch in CT is needed!  

It may be possible that theGulls are feasting on Slipper Shell (Family Calyptraeidae) larvae that inturn are feeding on the plankton.  Embryoshatch as pelagic larvae in some species or as crawling juveniles inothers. Field and laboratory evidence suggested thatthe postlarval juveniles crawled away from incubational substrates andassumed a drifting existence in the water column.  The pelagic stage lasts for 15 16 days and  that  stage the shell and velum of the larvae grow.

http://www.mendeley.com/research/the-aligned-enterprise-orchestrating-the-next-level-of-performance/

http://www.int-res.com/articles/meps/65/m065p183.pdf

 Lots more sites too. 

It could be a combination of several factors –hatching Slipper Shells eggs, increase in Plankton which the Slipper shelllarvae eat and perhaps Blue Crab (will research them latter.

Anyway, I find this topic fascinating and I hopethe experts will share the opinions as well.

Two of the many sites I visited   

http://www.mendeley.com/research/the-aligned-enterprise-orchestrating-the-next-level-of-performance/

http://www.int-res.com/articles/meps/65/m065p183.pdf

 Lots more sites too. 

Why didn’t I go to college for my first love…marine biology…..

Donna Caporaso

Stratford, CT

 From Scott Kruitbosch:

     Charlie Barnard suggested that we put up a couple of photos Twan Leenders took of the 

samples Charlie provided him last year that he mentioned in detail earlier. Here they are in the CAS blog: http://ctaudubon.blogspot.com/2012/02/plankton-feeding-time-for-gulls.html

See for yourself and tell us what you think. Here's hoping we have many photos of masses of 

gulls coming in the next few weeks.

Scott

    Bonaparte's Gulls starting to gather at Short Beach in Stratford-

From Meredith Sampson:

    Scott et al,I have a couple of marine biologist friends - one is a PhD who is a professor of 

marine biologyat a university.  I can forward any photos to them and see if they can i.d. the samples.

Meredith Sampson  Old Greenwich

    

 From Bill Yule:

         Gulls-flock mass feeding....A great discussion of the bird food chain from my point of view.

Thanks for the responses to my questions and the discussion in general. Looking at the pics from CT Audubon they certainly look like barnacle larvae to my eye.  I guess one of my follow-up questions is this one: Given a dense mass of plankton near the surface are there also fish feeding on this food source and if there are fish what are they and how do we know that the gulls are feeding on plankton and not fish? If I missed to answer to this question in the thread already posted my apologies but it seems to me that this is an interesting phenomena and a good one to discuss here. Someone mentioned duck stomachs filled with plankton and I understand this... but gulls seem to be a different category in terms of their food preferences? 

Bill Yule

 From Donna Caporaso:

     Dennis - thank you for sharing the all that information!  I find this event so interesting and 

wanting to know more so I've been reading what I can find about it.  Unfortunately there doesn't seem to be a lot of information that pertains to Long Island Sound specifically regarding this subject or on CT's Slipper Shells.

To me there seems to be several events happening at this time. It is "spring" after all and flowers 

and wildlife a like are "blooming" around us everyday.  Far from being even a novice in birding or marine biology, what I read leads to more questions and some observations.  In addition to the Barnacles and other plankton that may be blooming now, I am inclined to think the Slipper Shells are also involved. There doesn't seem to be much info on the CT Slippers breeding cycle.  But articles I've been reading say they spawn anywhere from March to August (or June to September) in coastal waters.  They are found in large numbers in Europe (thanks to US Oyster exports), Chile and along the eastern coast of North American. The Sound is not like a lot of coastal waters, it's more "protected coastal waters". There are concentrated large populations of Slipper Shells along LIS's coasts (Long Beach for one).  According to wunderground.com the coastal waters in CT and surrounding areas the past month have been above 40F hitting 46F several times and even higher in other locations http://www.wunderground.com/MAR/AN/330.html.  Slipper shells will readily spawn within a short time after being in water 25c/39F.  If its not Stratford area Slippers, then perhaps larvae from surrounding areas within LIS are travelling in the currents with the Gulls following along.  As the water continues to gradually warm up, various other larvae are added bringing more and more gulls.  It is interesting to note that Slipper larvae will float around for up to 4 to 5 days before they attach themselves to a hard surface such as rocks (like the barnacle does) and begin the process of "growing" their shells.  The photos from Keith clearly show the Gulls feasting on juvenile Slipper Shell larvae.  It seems the Gulls are feasting on a buffet of barnacles and Slipper Shells and ?? 

I think this phenomenon as it pertains to Long Island Sound would be worthy of being studied 

more fully. How does it coincide with the migratory shore birds passing through or leaving our area?  Did a milder winter cause an earlier spawn of all or some the different plankton? Etc., etc?? 

"The normal breeding period for C. fornicata in Woods Hole, MA is reported to be mid-June 

through mid-August (Costello and Henley, 1973), however; it is likely that animals begin spawning in May, and a few animals continue to lay eggs in August. This seasonal limitation is removed by the fact that one can obtain animals from the wild between November and May that will readily spawn within days to a few weeks of being placed in warm (25 °C roughly 39 F) sea water. Animals can be kept in chilled sea water tanks at 12°C for up to a month, without feeding, and subsequently warmed to 25 C when embryos are needed. It is imperative that these “off-season” animals be collected from the cold and shipped with ice packs to prevent them from spawning during transport."  http://www.life.illinois.edu/henry/crepidula_methods.html

Interesting article re Nantucket Slipper Shells.  BTW - they are edible (see article). And,  they 

have used them to determine the age of Horseshoe crabs. 

http://www.yesterdaysisland.com/2010/science/3-hermaph.php 

  List of some articles I need to go through

http://ase.tufts.edu/biology/faculty/pechenik/publications.asp 

Thanks for letting me share my "ramblings" on this subject.  Please feel free to send my 

your comments privately so we don't clog up the list here.  Slipper Shells are quite interesting. And when out walking Long Beach I will now have a new interest in them. 

Donna Caporaso

Stratford, CT

   Ring-billed Gull roost by the Stratford Seawall.

  From Paul Cianfaglione: 

    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

From Greg Hanisek:

     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 western end of the Sound.

Greg Hanisek
Waterbury

 From Paul Carrier:

     We all know - microscopic plankton and other such organisms are the main fare
for the largest animal in the sea - the Whale. So if they can catch and subsist
on these small microscopic creatures etc, then why not Gulls? yes?

I remember seeing great thick blooms of  microscopic Algae in fresh water, that
could easily be scooped up by any creature and eaten. By bird bills or any large
to small mouth. If food is there, than their is a creature that will take
advantage of it, no matter how big or small. Just my thoughts............

Paul Carrier

 From Al Collins:

     I saw another example of opportunistic feeding on plankton I though I should add to this very interesting conversation on plankton.

On July 31 of last year while fishing off of a rock pile mid-sound between Greenwich and Oyster Bay, LI I saw many small animals feeding in the top few feet of the water column. They were swimming like squid, which is what I thought thew were until I caught a few in a bucket and realized that they were a sandworm (or similar polychaete). They were between 1/2 and 3/4 inches long and darting around. The school extended at least half a mile to the north and south of me. Here's a photo:

http://bit.ly/xp6noB

Feeding on them were many scattered gulls, including Greater Black-backed, Laughing and Herring; common and least terns; schools of filter-feeding menhaden (bunker); normally bottom-feeding fish including scup (porgy) and black sea bass; very small bluefish; and schools of small fish that looked like spearing. Feeding on the feeders were bluefish and striped bass.

In the few hours I was in the area the worms were steadily drifting by; certainly many hundreds of thousands and probably millions went within a few yards of my boat.

Al Collins

 From Larry Flynn:

     I believe the worm in Al's photo is what fishermen refer to as a Cinder Worms, it should be in the Nereidae Family, which species I have no clue.
I have seen this hatch ( I believe they are spawning) many times around the Norwalk Islands, this event is most common  in July. I can't say I ever recall seeing them in the middle of the day, but rather in the darkness of night and into the morning, usually finished by 7-8 AM.
It is a remarkable event and draws the attention of the many opportunistic predatory birds and fish.
Again this event takes place in the warmer months not in the winter or spring. Years ago I did hear of something like this taking place close to shore on the south shore of LI in the colder months, although the fellow mentioned they those were larger worms.
Also of interest was the spawning cycle of the "slipper shells" as the water warms in early summer,
oysters are also doing the same thing at the same time, I'm sure these two species are not alone.

Larry Flynn

     These images were taken at Long Beach in Stratford during the height of the feeding blitz! It was very difficult to photograph the birds so you could fully see the massive numbers of Gulls and waterfowl. The magnitude of the huge numbers of birds were not possible to capture on a few images. Just as Charlie Barnard stated above, the rafted birds stretched from Stratford Point all the way to Bridgeport. To understand how many birds were present, just imagine these images stretched out to the length of a few miles of shoreline! That's how many birds were there!

    The day these images were taken, the wind was blowing strong out of the southwest so whatever mico-organism was present in the bio-mass, these birds were gorging themselves on what was being blown towards the shoreline. Because of the wind, the birds were speread out along the beach as far as you could see up and down the coast. Although with all of this activity going on, a large number of Ring-billed Gulls were heavily feeding on Slipper Shell flesh (just like the Bonaparte's Gull images above) along the eastern end of Long Beach by the point. I was standing very close to them and watched them gorge themselves on the snail-like flesh.

    From Dennis Varza:

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.http://www.yesterdaysisland.com/2010/science/3-hermaph.php

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 gulls.

Keith Mueller

Killingworth, CT

March 09, 2012

From Frank Mantlik- 3/9  Stratford
-  Long Beach, 9 - 10 am:  7000+ gulls (6500 Ring-billed,  500 Herring, 3
Bonaparte's, 1 Great Black-backed, 1 ICELAND - 1st cycle) surface-feeding about
0.5 - 1 mile offshore, about where the oyster boats were again working.  The
band of gulls extended for 1-2 miles.  I counted conservatively by 10's as I
panned with the scope.  The flock continually flew/moved to the south /
southeast, heading farther out into the Sound, following the barnacle larvae
plankton.  When I returned at noon (high tide, calmer seas), many of the gulls
were scattered, and sizable flocks had gathered on the beaches to rest and preen
(feathers flying).  Other highlights: 3 AMERICAN OYSTERCATCHERS flying west
towards Bridgeport.  Many expected ducks, Brant, loons, shorebirds. 

March 09, 2012

From Paul Wolter- 

3/9/12 Madison, Hammonasset Beach SP. About 3 pm today 147 Bonaparte's Gulls joined with many more Ring-billed and Herring Gulls feeding on the water about one hundred yards offshore to the east of Meigs Pt. They were also joined by 6 Black Ducks and 8 Greater Scaup. No frenzy as the Gulls floated and pecked at the surface. By 4pm the flotilla had drifted about 300 hundred yeards offshore as the tide fell. Noteworthy was that three Great Black-backed Gulls did a low level flyby apparently disinterested.

From Larry Flynn-

3/16/12 Norwalk Islands.

While clamming on the islands this afternoon, I saw large flocks off birds a mile or so past Copps Island. Around 3:00 I decided to take the boat out there to see what was going on.
The further I got away from shore, the more birds I could, until finally almost two nautical miles past Copps Islands I was in flocks of birds as far as the eye and binoculars could see, these birds were all plankton feeding and  species included Herring and Ring-billed Gulls, Brant, Long Tail, Scoter, Greater Scaup, Black Duck, Mallard and I'm sure I missed a few.
The number of birds was tremendous, guessing 10K may just be the start.
This plankton bloom was in over 50' water and the plankton were easily seen  floating on the surface.
I could see birds on the surface in a mile wide stretch that headed east and west I far as I could see.
There were also smaller groups in shallower water outside the islands.
Amazing!
We hope to research this further on Saturday.
Where the flocks also in Stamford today?

Larry Flynn

From James Purcell-

3/15/12 At Penfield Reef this afternoon I came home to finally discover a good concentration of gulls. There are at least a couple thousand, all Herring, Ring-billed, and Great Black-backed, no Bonaparte's unfortunately. However, I did not scan the gulls thoroughly at all so there could be an Iceland or Lesser Black-backed Gull or something in there. I was just happy to see the concentration  plankton-feeding, along with some Brant and Goldeneyes. This is still is nowhere near the peak I saw last year where there were more than 15,000 gulls, but that occurred on March 22nd of last year, so I imagine that the best is still to come. Ross' or Slaty-backed Gull anyone....???

James Purcell
Fairfield

From Patrick Dugan, David Winston-

3/12  Stamford  Cove Island Wildlife Sanctuary (CIWS) 1 Ad Black-headed Gull  hood all most full. 1st year Iceland Gull  feeding with about 3300 Gulls

From James Purcell-

3/16 At Penfield Reef this afternoon I came home to finally discover a good concentration of gulls. There are at least a couple thousand, all Herring, Ring-billed, and Great Black-backed, no Bonaparte's unfortunately. However, I did not scan the gulls thoroughly at all so there could be an Iceland or Lesser Black-backed Gull or something in there. I was just happy to see the concentration  plankton-feeding, along with some Brant and Goldeneyes. This is still is nowhere near the peak I saw last year where there were more than 15,000 gulls, but that occurred on March 22nd of last year, so I imagine that the best is still to come. Ross' or Slaty-backed Gull anyone....???

From Tina Green-

3/17 As of 8am,thousands of mostly Herring and Ring-billed Gulls feeding on the water and on land between the Norwalk   Islands to Burying Hill Beach in Westport and also Southport Beach. Glassy conditions on the water and perfect for viewing. Addendum-

Flock of about 60 Bonaparte's Gulls just arrived on shore.

From Frank Mantlik-

3/17 3/17. Milford, Laurel Beach, 10 am- about 2000 - 2600 gulls plankton-feeding close to shore. Ring-bills/Herring: 70%/30%.  Also many Brant and ducks. This location is the beach east of Milford Point and west of Walnut Beach. Nothing rare seen, but birds more birds kept flying in.

Stratford, foot of Cove Place (Russian Beach), 11:30 - 500 gulls scraping stuff off rocks as tide falling. Flock of 25 Bonaparte's flew by.

From Kathy Van Der Aue-

3/17 10 a.m. I was at Sherwood Island State Park with the Western Ct Bird Club, aand about 12 observers including Larry Fischer and Angela Dimmit.  We saw a raft of about 3,000 gulls, about equally mixed Herring and Ring-billed with a few Great Black-backed fairly close to shore and out further, stretching off toward Southport Beach, another very large raft of about 10,000 ; same species distribution.  We also saw Red-breasted Mergansers, Scaup, Common Loons, Widgeon sp. (we tried to make him into a Eurasian but

every bird seemed to have a golden glow about the head, so we gave up), Horned Grebes, Common Goldeneyes, a few Brant and Larry saw a Canvasback.  We went to Compo and saw about seven Long-tailed Ducks, few gulls.  At Burying Hill (in hopes of the absent Lesser Black-backed) there we also few
gulls

From Donna Caporaso-

3/17 Around 1pm today I was happy to see the usual number of Gulls at Long Beach.  Around 4:30 the same thing but with about 1000 Brant out just past the Jettys.  Around 5:00 I noticed the Gulls on the beach heading out and saw flocks of them coming in from the south with very few coming in the from the north.  There were several thousand Gulls and Brants in stretch from the 2nd jetty to above half down to the third.  It seemed to be a narrowish band of birds (in the current perhaps?) feeding out there and the Gulls and Brants were vocal. I have photos that I will post a link to later when I post the rest of my great day of birding around town!

From Dennis Varza-

3/17 Boat tour: Norwalk Harbor to south side of Chimon Is. then working the deeper water east to Sunken Island in Fairfield. The return trip was inside the islands.

2:30 to 4:30 with Larry Flynn, Frank Mantlik, Dennis Varza

We started in the area south of Chimon Islands where Larry had the large numbers yesterday. The area was practically empty. We then worked our way to the east were birds were reported at Southport Beach and Sherwood Is. In the off shore area from Southport Beach To Penfield Reef Birds were everywhere. Looking in the water, we saw brown ribbons of clustered larvae. In some areas the larvae were below the surface and in such density as to turn the water brown.  On the return trip closer to shore thousands more were found from Southport Beach to Cockenoe Island. The number of birds observed were so large that the estimates are very loose. We have come to believe that the gulls seen yesterday in Norwalk are the same ones in Fairfield today. And, likely the same ones in Stamford earlier in the week. It seems that they travel further than expected to find the barnacle plumes. Earlier in the week when Frank and myself had no gulls in the Bridgeport-Stratford area and they were not directly off shore, they were likely in the Norwalk-Stamford areas.

From Nick Bonomo-

I birded from about 11am until 3pm along the coast from West Haven to Milford mainly in search of plankton feeding birds. Between St. John's By-the-Sea (West Haven) and Charles Island (Milford) were varying numbers of plankton-feeding gulls and waterfowl. When I started, most of the birds were either just offshore, roosting, or feeding on the rocky shoreline. Around 2-3pm most of the action shifted further

offshore.

My gull numbers were largely in favor of Ring-billed Gull over Herring (at least 4:1). Some Bonaparte's Gulls were scattered between Oyster River and Charles Island with the largest group (40) being just east
of Charles Island. Amazingly, I did not come across a SINGLE uncommon gull species despite scouring a few thousand birds seen well enough to ID. Don't know what the odds of that are, but they can't be high!
Plankton-feeding waterfowl were also abundant, most notably Brant. Today I enjoyed watching a few species I had either rarely or never before seen feeding on the plankton, such as EURASIAN WIGEON, Lesser Scaup, and Bufflehead. This is an amazing event to observe, even if you don't hit the motherlode of gull numbers that Tina/Frank/Larry/Dennis had off the Westport area today.

On my way home in the afternoon I noticed that the plankton activity shifted further east, as I was scoping white specks on the water that  were in the vicinity of Lighthouse Pt in New Haven.

Here are some locations and select numbers (not comprehensive), from
east to west.

West Haven, Bradley Point:
Brant  140
Ring-billed Gull  300
Herring Gull (American)  90

West Haven, St. John's By-the-Sea:
Brant  350     plankton feeding
Lesser Scaup  19     plankton feeding
Ring-billed Gull  200     plankton feeding
Herring Gull (American)  30     plankton feeding
gull sp.  450     plankton feeding

West Haven, Roberts St:
Brant  50     plankton feeding
EURASIAN WIGEON 1     drake among Americans plankton feeding
Ring-billed Gull  125     plankton feeding
Herring Gull (American)  75     plankton feeding

West Haven/Milford, Oyster River mouth:
Brant  205
Bonaparte's Gull  10     9 ad, 1 imm
Ring-billed Gull  1100
Herring Gull (American)  275

Milford, Beach Ave:
gull sp.  300     plankton feeding

Milford, Burwell Beach:
Bonaparte's Gull  16
Ring-billed Gull  70

Milford, Morningside Drive:
Brant  30
Bonaparte's Gull  2
Ring-billed Gull  24
Herring Gull (American)  2

Milford, Point Beach:
Bonaparte's Gull  25
gull sp.  650     plankton feeding

Milford, Silver Sands SP:
Brant  80
Green-winged Teal  2     plankton feeding
Bufflehead  9     plankton feeding
Northern Gannet  4     adults
Bonaparte's Gull  40
Ring-billed Gull  250
Herring Gull (American)  30
gull sp.  400

From Stephen Spector-

3/18/12 -- Fort Trumbull beach, Milford (btw Milford harbor and Charles Island tombolo) -- at around 5:00 PM, 2500 gulls (4/1, Ring-billed/Herring) surface feeding with 5 N Gannets diving.  Also a few Bufflehead and Brant mixed in.  Spectacular sight only about 200 feet from shore, drawing interested neighbors and passersby.

From Nick Bonomo-

3/18 I birded back and forth between Sherwood Island SP (Westport) and Southport Beach this morning. There were many plankton feeders about, again. I estimated about 10,000 gulls total visible along that stretch

of coast. Highlights were 3 Lesser Black-backed Gulls and 300 Bonaparte's Gulls.

From Nick Bonomo:
3/18 - Westport, Sherwood Island SP - LESSER BLACK-BACKED GULL (first cycle), 5 Northern Gannets, American Pipit Westport, Burying Hill Beach - 2 LESSER BLACK-BACKED GULLS (adult and
3rd or 4th cycle)

Fairfield, Southport Beach - EURASIAN WIGEON, LESSER BLACK-BACKED GULL

(same 3rd or 4th cycle bird from Burying Hill Beach), 300 Bonaparte's
Gulls


NOTE- With the unseasonable weather from the week of March 19 through March 23, Gull watching was impeded by morning fog on LIS.



From Frank Mantlik-

3/26 Southport Beach - just an update. The Bonaparte's Gull flock numbers 3300
birds, counted by tens to 1000 then extrapolated. The tide is now high and the
flock is resting on the water out of the wind off the private homes to the east
of Southport Beach.

The BLACK HEADED GULL (adult in full breeding plumage) flew in earlier, didn't
stay long, then departed (though probably still in area). Bob DeCandido and Deb
Allen also got to see it and photo it. I repeatedly looked through the flock but
saw no other rare species.  At times there was much turnover of birds coming and
going.
This is the largest flock of Bonies I've seen in CT in several years. I suspect
as the tide falls the flock may return to the mouth of Sasco Creek at Southport
Beach

Summary from Dennis Varza-

Part 1- People have a subjective sense of distance. What is far to one is close to another. In college, local students didn’t think much about driving 30 miles for a burger. Living in Fairfield, my mother wasn’t much concerned about going to Stratford for Shopping. But Norwalk, “Do we have to go all the way out there?” Near and far is as much about habit as actual distance.

When comparing sense of distance to birds, “As the crow flies” has as much perception as truth to it. Wings allow the coverage of distances in small amounts of time that we often underestimate.  We see a bird in an area and expect it to be there, or the general area, all the time. The use of tracking devices has helped, but is still a problem for the average person. I read a paper about winter eagles in Maine and they found it was not unusual for some to spend the day on Long Island and still return to roost at night. We see a bunch of gulls on Long Beach in Stratford, we expect them to hang out there all the time, or maybe over to Seaside Park in Bridgeport. Is it really that hard for them to travel to New Haven Harbor, Norwalk Islands, or Port Jefferson for the day?

In trying to understand the interaction between the gulls and barnacle larvae we wanted as many observations of gulls as possible to see how the observed distribution is different than during a non-barnacle episode. We has observations as far west as Greenwich and as far east as Madison.

Plankton Feeding Gulls were seen in the area around Charles Island in Milford. Observers estimated numbers to be less than 5,000 and rather scattered. Further east smaller numbers were seen in West Haven near the Milford Border. In New Haven Harbor no concentrations were observed, In Guilford off Shell Beach a small group of less than 500 were seen, and none further east.

Last Year there were 10’s of thousands of gulls off the headlands of Stratford, Lordship to Black Rock Harbor in Bridgeport. This year birds were scarce in Lordship on Friday 16 Mar., but on the 17th numbers were low in the morning but increased in the afternoon to  an estimated 3,000 birds.

From Chimon Island and west to Stamford, Shippan Pt. there were well over 10,000 birds on Friday 16th but were gone the next day.

The peak of activity was in the area between Penfield Reef in Fairfield and Cockenoe Island in Westport. Overall there were well over 30,000 birds present. Observers in the morning reported gulls close to shore in the morning and drifting further out in the afternoon. This indicates the plume of larvae were being pulled out with the tide.

The next day and increasing the the next several days, were record temperatures and a lot of morning fog and haze which inhibited further observations.

The barnacle event started on Friday in the Greenwich-Stamford then shifted the next day to the Westport-Fairfield area. East of there only small plumes were seen in Milford and Guilford. The Gulls observed appear to follow the plumes from great distances. So, on those days when the gulls “disappear” from the beaches and are not seen directly off shore were expected, are well likely to be miles away.

The distribution of the barnacle plumes are centered in the area from Stratford to Norwalk. Beyond this area they can be found in small numbers. As to when they occur  is still problematical. For this event there was satellite  data on Chlorophyl-a. On the 16th. There was no measurable Chlorophyl-a. while on the 18th, the western sound was dark with it!

There are many kinds of algae with many kinds of Chlorophyl. Chlorophyl-a is the bright green color found in most of the common algae. Because it is colorful it can be measured by the intensity of the color.

This past weekend, Drifts of gulls continued to be seen off Fairfield, but smaller numbers. I would guess that The gulls would have been of Stratford last week if they could be seen. Now, the final phase of the event should be seen. On jettys and rocky shore one will see the gulls scraping the rocks with the sides of their bills to get at the tasty tidbits.

Another thought on my mind is “How do Boanapartes Gulls fit into this?” Considering their small size one would expect them to really like barnacles. However, their migration in the state tends to be at the tail-end of the “season” so would only occasionally be experienced by them. When they do meet, they are rarely seen feeding! Is there something out there they like better?

Part 2- Background on the Barnacle Phenomenon

Earlier I mentioned that this phenomenon is unique to Connecticut, but never explicitly explained why.  It is all because of Connecticut’s unique geography. Connecticut is separated from the ocean by Long Island and the Sound which were produced by the Glaciers. Long Island Sound is an estuary with properties very different from the ocean. I sometimes think of it as Chesapeake  Bay on its side.

Barnacles need a rocky substrate and the distribution of rocky shores is very limited. Sand beaches go from Florida to New Jersey then along the south shore of Long Island, then up to Cape Cod. Hence no habitat for barnacles there. Rocky shores go from Mane south to northern Massachusetts then again from Rhode Island through Connecticut. Connecticut is kind of unique because the shore is a mixture of rocky headlands separated by rivers and streams and small sand beaches.

In the Harrison Ford Movie the “Patriot Games” there is an amusing mistake. Harrison Ford is an analyst working in the Pentagon (in Virginia). He has a birthday party at his house which is a mansion on a bluff overlooking the ocean. The nearest bluff overlooking the ocean would be Rhode Island. That would be a tough commute! In reality it looks like California.

Long Island Sound is funnel shaped, wide on the east ocean end and narrow on the west New York end. This condition forms several gradients. As one goes from east to west The differential in tide goes from 4 ft. to 8 ft. West winds blow water out of the sound making tides lower than expected. East winds blow water into the sound making tides higher than expected. That is why “Noreasters” are so devistating to the Sound. And, of course their effect diminishes as one goes west.

Sedimentary material from the rivers and erosion from the east creates the sandy beaches, such as they are. If one looks at the location of the sand beaches from east to west, they start out well up bays and coves such as Jordan Cove and become situated at the mouths of bays. Look at the bars of Milford Pt.

It is the sheltered aspect of the western Sound that promotes the formation of Barnacle plumes. Water has different properties for organisms of different sized. When one gets below a certain size water becomes more like molasses. As a consequence they have great difficulty moving in it. Large scale movements are determined by currents wave action. I recall a study in California where the amount of recruitment of barnacles at a particular location were determined by the direction of currents at the time of recruitment. If they were onshore they got great recruitment. If there were off shore currents they go little recruitment.

In western Long Island Sound. wave action is almost entirely determined by wind.  The stronger the wind the bigger the waves. The direction of the wind also has an effect.  The longer the reach (the distance the wind travels over the water) the greater the waves. When the wind is above 10 mph. one can expect 2-3 ft. waves increasing to white caps. When the wind is around 5 to 10 mph. one can expect 1 foot waves. Below 5 mph. the water becomes ripple to flat. It is during periods of light wind (less than 10 mph) that will cause the larvae to be stuck at the surface of the water. In the eastern sound one gets larger reaches and more waves in general.

So, although barnacles may be abundant and widespread from Connecticut to Maine, it is only the western sound that has the sheltered water that traps the larvae at the surface. In looking at a map the New England shore, Narragansett Bay caught my eye. Perhaps the bay provides enough shelter to produce the same phenomenon. I contacted Rhode Island Audubon and they reported nothing. The event may happen there, but on a scale too small to notice if one is not looking for it. I tried to contact Long Island birders and got no reply. I wonder if one has habitat like the south shore of Long Island to bird, does anyone bother to bird the north shore?

Dennis Varza
Fairfield