Hi folks,
It looks like everyone is busy putting Drymarchon together. I posted earlier that I would provide details on my mating observations, and the general theory I have developed and am following.
For my couperi, the mating season is halfway over. I started putting animals together September 16.
I have 16 adult females and only 3 adult males. In July, all three males were pacing the front of their cages seemingly in unison. I didn't believe that there was any possibility of successful mating at that time, but the males were telling me otherwise. On a whim, I threw a female into each of the males cages, but observed no mating.
The pacing of the cages by the males continued daily until I put the same three females in on September 16. All three were pounced on immediately by each male and I observed copulation. For me to legitimately verify copulation, the male and female must lock up, and stay locked up for at least two hours. If they separate before that, I will consider it non-success. Also, I expect to see enlargement of the cloacal region in the female during lock up. It is almost as if there is a large marble or small golf ball inside her.
Over the upcoming 2 months, I put new females into the cages and tried putting females back in that had mated already. By November 11th, the 15th female verifiably locked up (number 16 may wait till next year because of a skin infection in her tail). Without an exception, females that had mated once refused to mate again until at least one month after the first mating. This was so uniformly true that now I don't even try to put a female back for a second mating until 5 weeks following the first mating. The female will frequently slap the male in the face with her tail, like an iguana will do, and this discourages the male quickly.
Currently, 15 females have locked up once, and 10 have locked up a second time. I have tried 2 for their third, but it was only one month after the second successful mating, and they refused.
In September, the temperature had not cooled at all, here in California. I put the animals together because of the obvious mating instincts I saw in the males.
What seems more and more clear to me is a thesis I will now explain. Firstly, it is daylength and not temperature that induces couperi females to ovulate. When they do, they produce and release a pheromone that the males in the room smell, and this sets the males into motion, pacing the cages and trying to get to the female they smell. In July, there must have been at least one female that had ovulated. All three males responded to the pheromone they detected. I didn't put in the right female. If I had tried all 16 females, I am sure now that at least one would be receptive, and mating would have occurred.
Once a female has mated, she becomes non-receptive for roughly 5 weeks. After this time, she becomes receptive to a second (or third, or fourth...) mating. During the period of non-receptiveness, I don't believe that she is releasing pheromone. When she becomes receptive again, she begins to release pheromone again. Each female ovulates during the mating season, but the exact time this happens is dependent on the individual. It does not require contact with a male. A female couperi will ovulate sometime in the broad window between July and November.
I suspect that multiple matings increase the likelyhood of fertile eggs. I expect that female couperi in the wild become receptive, release pheromone, attract a male, and are mated as many as six times during their period of fertility each year. I can't feel eggs in any of my females now. If the follicles have become fertilized, they won't calcify until early in the next year.
Males are willing to mate up to twice a week, but I have had males that refuse to mate until one week after their last mating. Again, I am not specifying simple courtship behavior, but lock up for at least two hours.
When males are opaque they won't mate. I haven't tried opaque females.
Based on these observations, I am trying to achieve 3 or 4 matings for each of the 15 females. Only time will tell if I get a good percentage of viable eggs. Right now, the temperature is getting down to the upper 50's at night. I try to get the daytime temperature to the low 80's each day, because Indigos bask in the sun and even on cold winter days they can attain body temperatures in the 80's. Warm daytime temperatures have not impaired successful mating activity in my animals.
An aquaintance of mine, Paul O'Connor, published a paper in Vivarium magazine quite a number of years ago, describing silicone-like plugs expelled by his females about 6 weeks after their first mating. My suspicion is this is congealed male semen, which may block another successful mating of the female until the plug is expelled. His time frame for expelling of the plug matches with my time frame of non-receptiveness. He did state an observation that possibly contradicts mine, that he would observe mating behavior during the interim period before the plug was expelled. I need to communicate with him about his observations, but it may well be that he was observing male courtship behavior but not actual lockup criteria, meeting the requirements I specified above. My couperi are not shy about mating, they will do it right in front of me. I always verify that a minimum of 2 hours of lockup occurs, and enlargement of the female cloacal region, to conclude that mating had actually occurred.
I would like to suggest that the silicone-like plug, which I have not noticed (and probably would not have noticed), may serve the functions of blocking the release of pheromone by the female, and also causing her to refuse mating. There may be a substance in the plug that binds to and inactivates the female pheromone, or it may just be a physical barrier. The presence of the plug may eliminate her desire for mating. When the plug is expelled, the pheromone is released again, and the female becomes receptive to additional mating.
I am hoping to have a lot of baby Easterns in 2005. Good luck everyone.
Robert Bruce.
when you have 10 or 12 clutches of hatchlings?!!!