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An open conversation about the birds in your back yard and beyond

Evolving beak size saves Florida's Snail Kites

We generally think of evolution in terms of many, many years. Snail kites in Florida have made a life-saving change in slightly more than a decade.


The kites eat snails, small snails known as apple snails. The birds have lived on those snails for ever. Their beaks were the correct size for that prey.


Both species live in the Everglades. Water quality there has declined. Drainage had made some parts of the Everglades too shallow for the snails, other parts too deep for the birds to hunt successfully.


The kite population had declined from about 3,500 birds in 2000 to about 700 in 2007. Things seemed to get worse when an invasive snail species arrived. It is two to four times larger than the native apple snails. The kites had trouble extracting the snail from the larger shell.


Then, very quickly, the kites adapted. Historically, there was a natural range of kite beak sizes, some larger than others. The birds with larger bills had less problem with the larger snails. 


The kites found more nourishment in larger snails. They survived to produce chicks with larger bills. The generational change continues. Larger bills produce larger bills.


Thirteen years after the invasive snail appeared the kite population of 700 has tripled. 


Scientists studying the kites call the change “incredibly rapid.”


A study of this behavior recently was published in the journal Nature Ecology and Evolution.

Benefit for Sax-Zim bog will be held Jan. 29

A benefit for the Friends of Sax-Zim Bog will be held Sunday, Jan. 29, at the Springbrook Nature Center in Fridley. The non-profit Friends group’s mission is to preserve, protect, and promote this important birding area. 


The event is billed as the Boreal Wings Gala. It runs from 2 to 4 p.m. Featured will be a presentation by the man who in 2016 set the North American Big Year record, Olaf Danielson.


Advance registration can be made at Price is $25, and that includes a one-year membership in the Friends’ group. Kids 17 and under are free. Admission at the door will be $30.


There will be hiking, skiing, and snowshoeing on the center’s trails. There are inter-active displays in its new building. Appetizers will be served. There will be a silent auction.


An update on Sax-Zim projects will be given at 2:30. 


Danielson will talk about his North American Big Year and show photos. You can preview his talk at his blog,


Danielson has a Minnesota connection. He lived on Park Point in Duluth in the late 1980s while going to medical school. He grew up the Swedish immigrant community Falun in northern Wisconsin, graduating Grantsburg High School in 1984. He graduated Ripon College, and medical school at the University of Minnesota.


He is now a resident of Milbank, S. D.     


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