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I haven't the slightest. I didn't know the sex of mine till he was about a year old and started mating. He's also significantly larger than similar age females so that was a giveaway as well. I think you can vent them but it's not my expertise by any means.
Sexing EBJD is extremely tough since they share very similar characteristics unlike regular jacks, but looking at the pic and going off head shape and finage I would say it's a female.