Well since it was mentioned, as far as I'm aware monitors don't really have much of a breeding season in captivity, or at least it doesn't come with the psychotic hormonal issues that igs can have. Not really sure if there's a certain time of year for them, I know my ackies seem to get in the mood at least a couple times a year, sometimes 3 times.
Oh, forgot to add that igs and savs at least are similar in that they can and will become gravid even in the absence of a male, and may either lay or re-absorb the eggs.