In our reports we often declare animals as "subadult" rather loosely,
and usually nobody objects...
Perhaps the best definition of "subadult" can be found at "Biology online":
subadult - stage in which an organism has developed many but not all
adult characteristics and is not sexually mature.
The second defining condition is unambiguous, but the first one leaves
some free space for rather liberal estimates....
However, regarding the second, strict condition, if you catch an animal in nature,
on what grounds can you decide/determine whether it is sexually mature or not?
If it's obviously old enough or too young, than it's easy, but that just REVERSES
the original question - you DECLARE it to be sexually mature/immature on the
grounds that it obviously IS an adult or a juvenile.
My raising this "theoretical" issue was prompted by a question from a colleague who
was lucky enough to catch and measure 40 (!) individuals of Elaphe quatuorlineata
on the island of Olib (in addition to 10 M. insignitus and 4 D.caspius!) last week.
Three of the E. q. were obviously juvenile, but some of the others, with total body
lengts reaching 110 to 120 cm still showed the transverse dorsal coloration pattern.
Should they be classified as "subadult" solely on that grounds?