Temperature & Humidity
For Short-Tailed Opossums (STO)
By Molly Kalafut
Introduction
Temperature and humidity are both important issues to be aware of when purchasing and housing a short tail opossum. The opossums are from warm to hot parts of South America originally, and cannot reproduce or will even die at temperatures that are too low. While they once required a high amount of humidity, captive breeding programs have been working to lower the humidity range needed.
Most retail pet stores sell small, reasonably priced meters that measure temperature and humidity. These can be placed permanently or temporarily inside the opossum cage to check exactly what their conditions are like. STO generally need 70-85 degrees temperature and 40-50% humidity (though less or more isn't usually harmful).
Remember that when increasing the temperature, the humidity should be increased as well to prevent excessive dryness.
Temperature
It is important to regulate the temperature for short tail opossums to make sure they receive somewhere between 70-85 degrees. Too far below 70 degrees and your STO may become susceptible to chills, pneumonia or even die from the cold. To increase temperature for your short-tailed opossum, you can use under-tank heaters that can raise the temperature near it up to 10 degrees, a reptile or other small pet heat lamp (non-UV light) which can be directed at certain parts of the cage, or even put a small space-heater near the area. To prevent over-heating, make sure your STO can always retreat to a cooler part in the cage if necessary.
Many people ask if their short tail opossum "has" to be supplied with a heater to be kept at 75 or 80 or 85 degrees, and worry 70 might be too low. My answer is that consistency within a range is the most important part, and whether it's regular house heat or a heater doesn't matter as long as it's consistent. A STO kept at 70-75 degrees would be uncomfortable to be suddenly moved to 85 degrees. Similarly, a STO used to 80-85 degrees would also be uncomfortably chilled to suddenly plunge to 70 degrees. So the important part is establishing a consistent temperature range, and if you need to move outside that range to do it slowly. If your house temperature is kept around 65 degrees, you'd probably want to use an artificial heater. But if your home is kept at 70 degrees or more (and doesn't fluctuate much) that should be fine.
It is particularly important to keep the temperature warmer than usual for lactating mothers with their litters. Young STO are unable to regulate their own temperature and rely on their mother for warmth. If the temperature is too cold, the mother will be unable to keep them all alive. Many breeders keep their nursing mothers in temperatures upwards of 75 degrees.
Humidity
Research and university facilities usually keep their short-tailed opossums with humidity between 40%-60%. Most homes in the US meet or exceed this humidity level normally and many STO are fine with humidity lower than 40%. Some STO react poorly to low humidity and suffer from excessively dry ears or tail. This unfortunate problem has luckily become less common over the last few years. My STO has not had any ill effects at 20% humidity. But owners concerned about humidity have several options to artificially increase humidity, including a small humidifier, extra water dishes in the cage, reptile waterfalls or even reptile cage misters. Be careful not to over-humidify the cage. 70%+ humidity can encourage the growth and spread of bacteria, especially in their fresh food.
