Understand the danger and risk involved in breeding short-tailed opossum (including but not limited to a maimed or killed mother, maimed or killed father and/or killed litter.)
Understand that female short-tailed opossums are "induced ovulators" and learn how that is different from most animals that go into heat on a regular basis. This helps explain why the pairing process has to be done carefully, how long it will take for the female to enter heat, and why it is important to remove the father after successful (or unsuccessful) mating.
Choose the mating pair. Know the ages of sexual maturity for males and females, frequency of litters, inbreeding, and factors in choosing a mating pair.
Prepare the cage(s) for breeding, supply nest-boxes, decide how many (if any) exercise wheels to provide, and adjust daylight schedule. Decide whether you will add the male to the female's cage (most common), the female to the male's cage (less common), or hook the two cages together (least common).
During daylight hours, put the opossums in the same cage (or hook together two cages). Monitor the pair very closely during the initial introduction - some threatening and chasing is normal, but be sure to separate the pair if excessive aggression occurs. Read about what threatening behaviors are common when first paired together and throughout the mating process. Make a note of what date you placed the pair together - this will be important later for deciding when to separate the pair.
Monitor the pair for mating, or mating behavior. Learn to recognize mating, and signs of successful mating. While occasionally mating may take place immediately, most paired STO mate successfully 7-9 days after being placed together.
Separate the pair. If you observe mating 6-10 days after they have been placed together, separate the pair immediately. Separate the pair immediately if mating is not directly observed, but the female has suddenly become more aggressive towards the male about 8-9 days after the pairing (a common sign she in no longer in estrus). Separate the pair for sure by 12-14 days after pairing (even if no mating is observed, or renewed hostility).
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