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bruce wrote at 2010-03-14 03:45:21
It seems clear to me that the ducks are feeding on something ad they are always poking their heads under water, the question is what are they feeding on?  I've seen this event many times on the small ponds and lakes around Broomfield CO.  The rotation is not always the same.  Sometimes it a flock of 30 or more birds in the tight circle.


Ed wrote at 2011-01-04 04:27:03
It doesn't appear that the answer posted above about keeping the water from freezing is correct.  I am in central Florida, where everyone, including the ducks, know that any lake of a reasonable size won't be freezing over.  However, over the past two years, I have observed that behaviour 5 different times, with the number of ducks involved ranging from 6 up to about 20.  Until today, they have always circled counter-clockwise.  However, today, the 6 ducks we watched went counter-clockwise, but for a short time, did go clockwise for about a minute.  Since all the birds are feeding constantly, we guessed that they may have some food caught in the whirlpool created, which likely brings the food to the surface.  I can't believe some bird expert somewhere doesn't know the reason for this behavior.


Linda wrote at 2011-03-22 14:36:21
The ducks that you see swimming in circles are Northern Shovelers.  They are in fact feeding. By swimming in a circle together, they cause a rotation in the water and just like a tornado, that rotation brings food to the "eye" of the circle.  They are the only duck that I have seen do this.  Very smart.





Linda Neely Liaison Wild Bird Information & Rehabilitation of Denver.  


BirdWatcher wrote at 2012-11-03 23:52:21
The ducks I see doing this are Mallards and they only do this when the weather gets colder.  I live just SW of Denver, CO.  


Accidental Birder wrote at 2013-12-08 17:07:09
We have for the first time in about ten years on this lake seen Mallards, 6-8, circling and appearing to feed.  We are in the midst of abnormally early winter snow and ice, the "wintry mix".  Ducks are in shallow water which is still warm and not at risk of freezing.


Bob wrote at 2014-01-25 19:52:58
I observed this today with about 3 to 4 groups of ducks moving counterclockwise in a circle with their heads underwater coming up for air periodically, but maintaining the same speed as the others in the circle.  I assume this is like other predators feeding in the water.  Whales create a vortex to confused the krill and them swallow them, sort of like maybe our governments does.


Courtright wrote at 2014-01-27 17:31:36
http://www.stanford.edu/group/stanfordbirds/text/essays/Duck_Displays.html


sonnyg wrote at 2014-03-06 04:47:26
The idea that the ducks are keeping 'the lake from freezing' doesn't make sense in Palm Springs, California.  We just observed this vising friend's home where there were a number of ponds where the ducks gathered...in twos, fours or many more.  I buy the theory of their bringing food to the surface.  These are shallow ponds, but it must be true there too.


DrCohen wrote at 2014-12-27 00:08:13
We just (December 2014) spent a week playing the Sandals Emerald Bay golf course on Great Exuma. Saw groups of around 20 birds (grebes, I think) doing swimming in a very tight circle, all facing center, every day in several ponds. Unfortunately, we didn't photograph. But anyone who tours the golf course should see them.


RDW wrote at 2015-11-30 19:48:46
I have observed this also in the lakes in Central Park multi colored ducks swimming counter clockwise and clock wise with their heads in a circle:up to anywhere from three ducks to maybe 20 ducks. Beautiful on the 30th day of November,15. Have been observing this activity for at least 3 weeks. It adds such beauty and ecology to New  York city, along with geese,turtles,red tailed hawks and array of bird species...


amethyst wrote at 2016-11-30 20:53:13
We live near a large lake in Arvada, CO, and we have observed ducks doing their circles year round, hot or cold.  We figured out ourselves they were feeding some how...I don't think it has much to do with the temp of the weather OR the water....its just probably more obvious when the weather gets colder, the water gets colder and it may be harder to bring their food up to the surface?   The circles vary in size, bit we DID notice that the colder it is, the LARGER the circles become...many more ducks are in one circle.  These are Mallard ducks and just plain wild ducks...fun to watch...




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Roger Lederer

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Any and all about WILD birds - the science of ornithology. Information about birdwatching, ecology, conservation, migration, behavior, banding, rehabilitation, feeding, songs, binoculars, identification, and careers in ornithology. No questions about pet or caged birds, please.

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