Remember about bird physiology:
(If you plan to go bird)
Herbivore birds generally have long necks and short tails, while predatory birds are the other way around.
Analogy would be herbivores=trader, predatory=fighting ships.
eg Swan/Geese vs Swallow/Hawk/Eagle
(Harriers are just strange, with their long necks and feet eating frogs and fish.)
Multipurpose ships would fall into the category of Finches and Raven etc. as well as Gulls.
Nice big birds are Jan-van-Gent (Northern Gannet), Albatross, Vultures, Eagles, Kasuari, Emu, Ostrich.
A nicely stuffed Turkey will wet any pirate's appetite.
Cloaked ships might be named after Owls.
There are many more interesting birds...
http://en.wikipedia.org/wiki/BirdBottom of page has a list of families.