I observed a squirrel behaving oddly in the neighbor's back yard yesterday. It was not running, but hopping, jumping and rolling. Then it climbed the fence and chased a robin in our yard, dug in the ground, rolled and hopped some more before departing into the woods.
Sometimes baby squirrels fall out of their nest and/or become orphaned. When that happens they can become stunned and act odd, or, if they are orphans, they usually have no fear of humans and often close their eyes and emit a noise like "squee, squee, squee" as if calling for its mother. But, it's too early for babies and this was a full-sized squirrel.
Small mammals such as squirrels, rats, mice, hamsters, guinea pigs, gerbils, chipmunks, rabbits, and hares are almost never found to be infected with rabies and have not been known to cause rabies among humans in the United States.
So, even though squirrels are not infected as frequently as other mammals, such as raccoons, skunks, and wild canines, it is possible.
There are many physical signs that could indicate a squirrel has rabies. Overt aggressiveness, slow movement, and apparent confusion are all symptoms of the virus. Rabid animals also produce excessive amounts of saliva, which makes them drool more than usual and leads to the assumption that animals with rabies foam at the mouth. However, since many common diseases and parasites linked to squirrels cause the same symptoms, you cannot always be sure whether an animal is rabid. Still, any slow-moving squirrel exhibiting aggressive behavior should be assumed to have some kind of infection and regarded with caution. This one was anything but slow moving. One can probably rule out rabies as the reason for its squirrely behavior.
Other possible causes seem unlikely this time of year. Infestation by bot fly larvae can cause squirrels to act odd, but I don't think they live around here.
Distemper comes to mind. Distemper is a disease that affects a wide range of wild and domestic carnivores. It is often referred to as either canine or feline distemper, and these two illnesses are frequently confused. They are, however, caused by two completely different viral agents.
Symptoms in dogs include coughing, vomiting, and diarrhea. Eye discharge, anorexia, and disturbances of the central nervous system may appear as well. Symptoms in wild carnivores include abnormal behavior and lack of fear, often resembling behavior seen in animals with rabies. Purulent conjunctivitis and nasal discharge may be evident as well. Some affected wild animals exhibit signs of neurological disturbances, diarrhea, vomiting, weakness, and labored breathing.
Squirrels, as well as chipmunks, are rodents, just like mice and rats. They all belong to the order Rodentia. A conspicuous feature uniting squirrels with rats and mice is their teeth. In the front of all rodent mouths there are four chisel-like gnawing-teeth called incisors, two above and two below. Immediately behind the incisors there's a space, and then flattish back teeth that are used for grinding.
The vast majority of rodents also have four toes on each front foot, and five on each hind foot...who knew that?!
The biggest dangers to squirrels as hawks snakes, domestic house cats and in towns, cars. I even saw one that had been electrocuted when it got onto a transformer at the top of a telephone pole in front of our house. Hunters are a danger, too. Squirrels with biscuits and gravy are a popular meal with some people. You can find over 60 recipes for squirrel HERE.
One reason squirrels come to the ground is to bury and retrieve food. In the fall you can often see them digging small holes in the ground called caches into which they deposit food, especially nuts and acorns. On warm days throughout the winter, when food is scarce, they then dig them up, but many are never retrieved and develop into trees. Thus one important job the squirrel does in the ecosystem is to plant trees.
An interesting online book detailing the life of a squirrel can be found HERE.