How to Raise a Squirrel for Release
The prime directive for every wildlife rehabilitator is to return injured and orphaned wildlife back into the wild. This is hard for even experienced rehabilitators who have come to deeply care for individuals after long nights and hours upon hours of care. We may question ourselves and second guess our decisions, but in the end, when the time comes, we must dismiss our personal feelings and do what is right and fair for the animal. Underlying that goal when rehabilitating prey species, is the hope that all of our hard work doesn’t instantly get snatched up by the neighbor’s cat or the first passing car.
Most squirrels die in the first year of life (WDFW, 2004), with many sources citing death rates as high as 70%. As wildlife rehabilitators, we can’t guarantee a long life for any animal we release, only the opportunity to live that life. Nonetheless, there are several things we can do to up the odds.
6 Ways to Improve the Odds for Release
Ensure ideal nutrition so the the squirrel goes out with the necessary muscle mass and fat stores - not too lean so as to place him at risk for succumbing to cold or starvation, nor too fat to make him slow and easy prey. This starts by selecting an appropriate milk replacement formula when young, and again later when transitioning to a healthy adult diet .
Make sure food is are offered in such a way as to promote normal food seeking and storing behaviors. If a bowl of rodent block is served in a dish at 8:00 am every morning, the squirrel will be nutritionally sound but unprepared to recognize the foods available to it once released.
Provide opportunities for play and exercise. Squirrels love to jump from branch to branch, to pounce on a sibling, to chase and be chased. This play will prepare the squirrel to evade predators, avoid aggressive conspecifics, and successfully compete for a mate. It helps build muscle and muscle memory. At a minimum, a squirrel over six weeks old needs at least one hour in the morning and one at night of free exercise with orphans of similar size and ability, extending to several hours per day during pre-release conditioning. Appropriate housing at every stage of development is an essential part of providing opportunities for normal growth. Squirrels denied sufficient stimulation often display maladaptive stereotypical behaviors like excessive chewing on bars, pacing and flipping. These are all signs of impending damage, both mentally and physically. See side bar.
Ensure acclimation to temperatures; as well as, the sights and sounds the squirrel will be exposed to once released.
Raise the squirrel with other squirrels of the same species so that the squirrel learns social skills that are critical to mating, avoiding interspecies conflicts, warn other of predators, etc.
Ensure appropriate fear responses to predators (particularly - people, dogs and cats) and other dangers.
The Importance of the Family Bond
Northwest tree squirrels (grays, foxes, pine squirrels...) Do not pair bond. The young male doesn’t leave home and meet a girl squirrel in squirrel college, where they court, marry, and then move into a nice home to start a family in the squirrel suburbs.
Tree squirrels come together only during brief periods of breeding receptivity once, twice, or maybe three times per year (depending on the species) when the female will allow only those males lucky enough to catch her, the opportunity to mate with her. If a male approaches a female at any other time of year, she will bite his face off. It is not uncommon for littermates to be sired from different fathers.
That means that there are only a few relationships a squirrel will have in its life. A female will have a relationship with her mother, her siblings and her young, and a male with his mother and his siblings. A male squirrel that has no mama, brothers or sisters will have no other close relationships in its life.
Why is that important? These family bonds make that squirrel generally welcome in that group and ensure that he or she has a place in the nest box on a cold night. If he is dropped off outside of that group, he will likely be chased off. There are some behavioral differences between species when it comes to communal nesting in inclement weather, but the general idea here is that if the squirrels are going to have siblings and they are orphans, then there is a ‘window’ of time in rehabilitation to foster these relationships. I have found this to be generally before 8 weeks of age although, if given time and enough social distances, even other squirrels will come to accept new squirrels into their ‘group’, but its not guaranteed nor are those bonds as ‘tight’ as when you raise a group of babies under five weeks together.
Relationships that Do Not Mix
If you have a single Fox squirrel, then it's certainly better to put him in with the grays than to raise him separately, but if you have grays and you have foxes, then separate them to avoid confusion during breeding season. Squirrels do not have mirrors and even if they do, it's doubtful they have the thinking processes to achieve self awareness. It is reasonable to surmise that a fox squirrel surrounded by grays will think it is a gray and at some point chase around gray females who will not be amused at the fox squirrel’s confusion.
You can mix prey animals of different species that do not have a natural predator/prey relationship (like bunnies and squirrels) but you cannot release a squirrel that has been nurtured by a predator (such as a dog or cat - with the exception of humans since that cannot be avoided and we can take measures to restore their natural leeriness towards us).
Davis E, Down N, Garner J et al. Stereotypical behavior: a LAREF discussion . Lab Primate Newsl. 2004 [cited 2009-12-21]; 34(4):3–4
Garner JP, Mason GJ. Evidence for a relationship between cage stereotypies and behavioral disinhibition in laboratory rodents. Behav Brain Res. 2002;136(1):83–92
WDFW Living with Wildlife - Tree Squirrels. 2004. http://wdfw.wa.gov/living/treesquirrels.pdf
Please note: Washington State residents are prohibited from caring for wildlife.
This information is for trained wildlife rehabilitators only.