Bigamy in the Blue-footed Booby and the Brown Booby?

On islands in the Gulf of California in 2003 and 2004, we recorded three Blue-footed Booby (Sula nebouxii) and one Brown Booby (S. leucogaster) nests that were actively used by two females and one male. Although our data are limited, and cooperation cannot be completely ruled out, we suggest that these nests were the result of bigamous behavior.