We receive many phone calls during the winter months regarding wildlife behavior,  especially in regards to migration and hibernation. I had a phone call earlier this week regarding whether muskrats hibernate or not. As a thick furred mammal, many people think that they do or should be hibernating, but the opposite is actually the reality for these large rodents.

Muskrats do NOT hibernate, but ARE less active in the winter months in order to conserve body heat and energy. They spend most of their time sleeping and eating in their safe, warm lodges.  The muskrat’s home has to have an entrance that is located far enough under water that it will not freeze.  This way the muskrat will be able to leave its lodge to eat even when the water is frozen. Muskrats chew through the ice to create entryways into the water so they can forage for food out of the water.  After they create an opening, they build a covering over the opening out of cattails, grasses and mud.  A muskrat’s diet consists of aquatic plants, freshwater clams, frogs, small fish and salamanders. If these foods become hard to find, they can also survive on dry twigs, stems and leaves. The fur of the muskrat is very thick and keeps them very warm. It is nearly waterproof and helps keep them from getting wet. 

So don’t be alarmed if you spot a muskrat out during the winter! He/she is just foraging for food and will soon be back in the lodge warm, safe, and napping away

Fun fact: We admitted 13 muskrats in 2011!

Being over 4000 miles apart, it’s no wonder that the diversity of wildlife in Minnesota is completely different to that of the UK, but along with different animals, comes different diseases, and many different parasites.

A parasite which I have not encountered before my time here at the WRC is a type of roundworm, whose host is the raccoon. This parasitic worm is called Baylisascaris procyonis. It usually spends its life inside the gut of a raccoon, periodically shedding its eggs within the raccoon’s feces. To the raccoon, it is virtually harmless, but very widespread, infecting up to 70% of adults and 90% of juveniles. If it is harmless though – then why write a blog about it?

Since my time at the WRC, numerous other, ground-feeding animals, such as squirrels, rabbits and woodchucks have been brought in with suspected Baylisascaris infections. These animals have accidentally ingested the eggs along with their food whilst foraging. When this happens, the parasitic larvae migrate to their brain or eyes, which is not only potentially fatal, but can also cause visual impairments, substantial neurological damage and considerable lack of coordination.

I’ve also learned that Baylisascaris is a potential threat to humans. It most commonly affects children, as they are more likely to ingest contaminated soil or sand to which raccoons may have access. Unfortunately, there is no treatment which is known to completely eradicate the disease in humans, and in cases where the infection is not fatal, severe neurological damage can occur, along with blindness.

This is the direst warning we can give to people who find orphaned raccoons in their yard, and with the best intentions, want to care for and rehabilitate them. Not only is this illegal without the necessary permits from the DNR, but it is also incredibly dangerous.

On a positive note – not all of the infected animal patients admitted to the WRC suffer fatal damage from the parasite. Sometimes the worm causes only a slight visual impairment, or some minor imbalance. One of the neurological effects of the worm can also be a decrease in aggression, and lack of fear of predators. Although these particular animals would not do well in the wild, it does make them ideal for placement, given that they do not become stressed in the presence of humans.

Recently, an infected female woodchuck came in that stole the hearts of everyone at the WRC, not only was she approachable and friendly toward humans, but the sight of her munching on a carrot in her enclosure was enough to make anyone smile.

Happily, she was able to be placed at the Staten Island Zoo in New York, where she will educate a whole new generation of children to love wildlife as much as we do!

I love being a wildlife veterinarian!  However, working with over 160 species means that I need to know about many different types of animals; this makes me more of a generalist (ie. your family doctor) rather than a specialist (ie. an oncologist).  When an animal has a problem that I’m unfamiliar with and books aren’t helping, I’m not afraid to call in the true specialist for a second opinion.

This female mallard came into us after being hit by a car.  She had some wounds at the base of her beak and some scratches on one eye (a large one is visible in the photo below).

The scratches didn’t heal with typical treatment (antibiotics, pain medications), so I called an ophthalmologist.  Luckily, Dr. Olivero from the Animal Eye Clinic in St. Louis Park, is nice enough to volunteer his services for wildlife.  He examined the mallard with me and provided additional suggestions for its course of treatment. WRC is very lucky to have boarded veterinary specialists like Dr. Olivero to help our patients when needed.

Thanks to Dr. Olivero, this mallard is well on her way to recovery!