Cottontails refuse to breed
I have raised 6 Missouri cottontails. I got them when they were 6 weeks old. They are 8 months old now. I have 4 females and 2 males. I keep putting females in male cages but the females won't have anything to do with them just lay there.
Cottontails are a completely different species than domestic rabbits, so I'm not sure if I can help too much! But, assuming some similarities, here's some thoughts:
Were these cottontails wild when you got them? If so, they may have parasites that reduce their health levels and therefore their drives. Treat with Piperazine for pinworms, Albon for coccidia, and tapeworm cysts require an Rx for treatment. You may need a 'cottontail-savvy' vet....
Second, did you get in on some of that brutal heat we had this summer? If so, this might affect willingness to breed.
Third, it's September - right when wild rabbits' breeding rates are at their lowest. They usually take a couple month break from breeding during autumn...at least, our domestic rabbits frequently do.
Fourth, ensure a high quality forage/feed, with sufficient protein, at least 15-16%.
Hope this helps. At the worst, perhaps the cottontails will become more amorous by December/January. Hope so!