To get that Crow - you'll have to go a bit further
Isla Cangrejos is the only place the three of them hang out - but one of them hangs out behind and to the left of Isla Cangrejos - you don't usually see him unless you sail behind that island... the other is farther right from Isla Cangrejos towards the French island sometimes... Since the french don't hang out at any other island - just stick around Isla Cangrejos (and try to avoid the other bad ships about) until you find the third one