but the points should be arwarded to MLuisa :)) I was getting crazy about this, but 'gocai' really means nothing and I wasn't able to make any progress before readinf her note (even if I was searching all the birdwatching sites of Veneto. BTW Verona is in Veneto county not in Tuscany!!!).
Instead, cocal (pl. cocai) identifies the bird 'Sterna fissipes' whose popular name is 'sterna scura'. That is similar to a small seagull (but the colours are not identical).
Anyway, my advice is to call it just 'sterna' since the tassonomy of this species is very confused when you try to refer it precisely to the vulgar name 'cocal'
Just to make an example the Venetian Wikipedia classifies it simply as a 'Larus' (seagull) because to people the sterna is just a small seagull (http://vec.wikipedia.org/wiki/Laridae)
Instead, all the other references state quite clearly that 'gocal' is specifically used for 'Sterna'
http://books.google.it/books?id=QHHhqSYbSdgC&pg=PA177&lpg=PA...
http://books.google.it/books?hl=en&q=cocal sterna&btnG=Searc...
http://books.google.it/books?q=sterna cocal&btnG=Cerca nei l...
http://books.google.it/books?q=sterna fissipes&btnG=Cerca ne...
http://www.ilsalesullacoda.it/cartelle/fraticelli.htm





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Note added at 5 hrs (2008-03-17 00:49:15 GMT)
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Ah SORRY I was so busy understanding the Italian meaning that I did forget -ooops :)- that we were dealing with an ITA->ENG translation.
So the translation of cocai is

TERNS

i.e. the plural for TERN (cocal).

If you prefer to be more specific (but please consider the abovetold about the difficult to be sure about the popular ability to distinguish among the species of the genus 'Sterna') you could translate it as
BLACK TERN
http://books.google.it/books?id=1goAAAAAQAAJ&pg=RA2-PA270&lp...

:)