How to Warm a Baby Squirrel
Warm the baby immediately if it feels cool to the touch. If the baby is cold it must be treated for hypothermia, a condition where the animal's core temperature falls below normal. This can happen quickly when an injured and/or naked baby is exposed to cold, wet or windy weather.
The normal body temperature for a gray squirrel is between 99° and 101° Fahrenheit (F) or 37.4° to 38.5° Celsius, and slightly higher for a fox squirrel. It is vital that the baby be warmed to at least 99° F before attempting to reunite it with its mother or administer any fluids.
Administering fluids or food to a cold baby, or providing inappropriate nutrition such as cows milk, juice, or human infant formula will result in death since a colder than normal core temperature slows or stops the digestive system resulting in the fluid rotting in the gut.
Inappropriate foods cannot digest properly to provide needed nutrition. Rehabilitators often lose these babies because of the actions of well meaning people as soon as we warm them up.
The most important point to remember is that you must take care to ensure the baby is not allowed to become overheated or burned - always use common sense and monitor the heat source.
In all cases were a heat source is placed in the box with the baby, there must be ample room for the baby to move away from the heat to a cooler spot.
It very simple: Don't cook, squish, suffocate, or drown the baby!
Immediate (Temporary) Warming Methods
Some methods of heating are better than others, but do what you can with what you have readily available. The most effective methods surround the baby with gentle warmth, not just on one side.
Fan the baby with heat from a car heater, hair dryer or closely monitored heat lamp taking care not to overheat or burn the baby.
Wrap a microwavable heating pack in a towel and place it in the box with the baby or part way under the nest.
Fill a plastic bottle with hot water. Wrap it with a cloth and place it inside of the box with the baby. Ensure the bottle cannot roll on or come in direct contact with the baby unless wrapped.
Fill a sock 2/3 full of rice and microwave on high for 2 to 2 ½ minutes. Carefully wrap the rice in a towel and place it in the box near the baby. Take Care - the rice sock gets really hot! Make sure the baby can move away from the heat.
While holding the baby at all times, immerse the baby in a bath of warm (not hot!) water, ensuring its head is above the water at all times. The baby must be completely dry afterwards.
In a pinch, warm the baby with your own body temperature by cupping it in warm hands or against your body – make sure it can breathe! Warning, only use this method with babies that have no fur or that you know do not have fleas, mites or other ectoparasites. These are typically easy to see by closely looking at the baby. Reference the link to debugging at the bottom of this page.
Keeping a Baby Warm
Whether the baby squirrel is kept inside a box or a cage, a constant heat source must be provided until the squirrel is fully furred and has reached at least 5 weeks of age (longer is better).
Once a cold baby squirrel is warmed, keep it warm to prevent hypothermia and death. Ideally, a furless baby squirrel will be kept in an environment that's at a constant temperature of 100° F. A furred baby between 4 to 10 weeks will still be sensitive to cold; however, will do fine in temperatures between 96° to 98° degrees F.
If you have more than one baby, they will typically be able to maintain their body temperature by snuggling together in warm bedding, like fleece or cotton.
For more information on providing a suitable warm environment for the squirrel, follow the link to construct a makeshift incubator.
A warning about bugs!
Squirrels are relatively disease free animals and aren’t considered to be rabies vector species (see Zoonotic Diseases for more information); however, the insects that may live on and around them in nature can carry a variety of viral and bacterial agents that are best avoided! For this reason, one of the first things most rehabilitators do once a baby is warm and stabilized is to ensure all ectoparasites are removed! Please reference the Debugging Squirrels link for more information on how to safely accomplish this task!
Dispose of the nest!
You do not need to keep the squirrel nest; in fact, I recommend you immediately toss it outside in the trash UNLESS you plan to use it in your attempt to reunite the babies with its mom or place the nest back up in the tree. It may contain a variety of vermin that you are not typically interested in rehabilitating and you certainly don’t want in your home.