I have read from the book "Terns of Europe and North America, by Klaus Malling Olsne and Hans Larsson" that measurement of tail fork are different on male and female of Roseate Tern. The actual numbers for birds in the Caribbean (race dougallii) are:
Adult male: 80-136 mm, n=50
Adult female: 65-119 mm, n=29
Juvenile: 35-70 mm, n=11
Here is some photo taken in HK (presumably race gracilis from Australia).
A short-tail adult (likely female)