'(<a href="http://www.j-archive.com/media/2010-04-30_DJ_28.wmv">Sarah demonstrates a happy drinking bird.</a>)  An internal pressure imbalance forces liquid up to the duck's head, making it tip over for another drink; it's caused by this process that cools the wet head but not the dry tail'
evaporation
POPULAR SCIENCE: An internal pressure imbalance forces liquid up to the ducks head, making it tip over for another drink; its caused by this process that cools the wet head but not the dry tail
An internal pressure imbalance forces liquid up to the duck's head, making it tip over for another drink; it's caused by this process that cools the wet head but not the dry tail
An internal pressure imbalance forces liquid up to the duck's head, making it tip over for another drink; it's caused by this process that cools the wet head but not the dry tail
POPULAR SCIENCE
evaporation
POPULAR SCIENCE