What do you know about North America’s largest rodents, and in particular their unusual teeth?

Castor canadensis is an aquatic fur-bearing mammal that was eliminated in Pennsylvania and most eastern states by the end of the nineteenth century because of uncontrolled trapping and habitat loss, according to the Pennsylvania Game Commission (PGC).

But due to wildlife management strategies, beavers are back and can be observed in the Upper Delaware River region near waterways fringed with forested areas.

Throughout the region, beaver activity is apparent to the attentive observer. Commonly called nature’s engineers, beavers are masters at constructing dams that have earned the respect of many human engineers. To tackle this feat, beavers rely partly on self-sharpening front teeth that often appear orange or red in color.

 “The teeth are self-sharpening, in part, because the enamel on the front of the teeth has a higher iron content than the enamel on the back,” states the PGC. “The front of the tooth is harder and the back wears more quickly producing a chisel-shaped tooth. The iron produces the orange-red color of the incisors.”

Interestingly, beavers can close their lips behind their incisors to keep from swallowing or inhaling water as they gnaw on and transport saplings underwater. And while they prefer soft vegetable matter such as the leaves, stems and roots of plants like cattails and water lilies, they also eat the bark, twigs and buds of various tree species. When beavers do harvest larger trees, it is often done to gain access to the fresh growth above in the tree canopy.

Beaver breeding season in our region typically takes place during the first three months of the year, after which a gestation period of approximately 12 weeks leads to the birth of between three to six young. The newborn kits are fully furred, weigh roughly a pound, with eyes open and teeth emerged. In the wild, they will typically live between 10 to 12 years.