The thing with birdo, in the American instruction booklet for mario 2 it stated that Birdo was a guy. But in Japan the character has always been refered to as female. As for Yoshi I always assumed that that egg laying was just something true for all the species. Perhaps the species produces asexually and the main yoshi just happens to have more male hormones than female ones. Now back to Vivian, perhaps calling her man (i.e. mannish) is the same as calling her ugly. If not I'll just put it down to WTHIWWJP. If I say tenticle you should be able to figure out the acronym