Some years ago I was shown how to vent sex finches and I thought I had been given the keys to heaven-suddenly pairing up my birds became a breeze. Although it is most ohvious in Parrot Finches, it can be used on at least some other species; in particular, I have had great success with Diamond Sparrows and Greyheaded Social Weavers (the latter, I had confirmed hy surgical sexing because, according to at least one reference book, there is no way to visually sex this species).
I am told that vent sexing finches is the same as for sexing canaries, but since I have never sexed canaries I have to take their word for it. In general, the male has a very definite protrusion immediately around the vent, usually causing a crease across the helly-the female is flat and her feathers, if not entirely flat, at least point more toward the tail. For accuracy, the hirds need to be at least in adult coloring but I don't think they necessarily need to he in breeding conditionthou gh it is more difficult if they are going through a molt.
Those of us who use this method have close to 100% accuracy. It can be readily applied to Red-headed and Blue-faced Parrot Finches (as verified by successful pairing and breeding) and there is every indication that it also applies to Bamboo Parrot Finches ( verified at necropsy). I have not had the opportunity to try using this method on other Parrot Finches but it is my assumption that it applies to most, if not all, of them.
There has long been some confusion concerning the Bamboo Parrot Finches-mainly due to some misleading, if not totally inaccurate, information in some of our reference books. According to these books, the male Bamboo has a black band...