This is easy to believe having once been dive bombed by an adult swan
while dinghy riding in Hamburg Cove near the Connecticut River, and
having a chip taken out of the gel coat on one of out old sailboats on
another occasion. Swans are beautiful to look at but are very
territorial and nasty tempered.

http://www.chicagotribune.com/news/local/breaking/chi-man-who-drowned-in-des-plainesarea-pond-was-attacked-by-swan-20120416,0,4485875.story