Rodents

October 05, 2021

I had mentioned last year about the rodents I battled when I lived at a camp in Kansas.  As winter approached a rat took refuge in my truck and chewed through the distributer wiring.  The next year another (same?) rat again took up refuge and chewed through most of the trucks wiring harness.  I mention this because I came across the story of a man in North Dakota who has similar problems with rodents.  Rather than a rat chewing wires he has a squirrel storing nuts.  Bill Fisher has found gallons of walnuts under the hood of his truck after a red squirrel (Sciurus vulgaris) turned it into its hidden winter nut cache.  Every two years since 2013, Fisher has found the shelled Black Walnuts stuffed in the engine compartment.  This year he found 42 gallons of shelled (gnawed?) walnuts crammed into every corner of his truck.  Fisher was forced to dismantle parts of the truck to remove the walnuts.  It left me asking where the squirrel stores the nuts in the off years.

When I looked online, I found that Rodents (from Latin rodere, ‘to gnaw’) are mammals of the order Rodentia, which are characterized by a single pair of continuously growing incisors in both the upper and lower jaws.  Rodents comprise about 40% of all mammal species and are native to all major land masses except for New Zealand, Antarctica, and several oceanic islands.  They often travel with humans and have now been introduced to most of these land masses as well.  Rodents are extremely diverse and can be found in almost every terrestrial habitat, including human-made environments.  Species can be arboreal (climbing), fossorial (burrowing), saltatorial/richochetal (leaping on their hind legs), or semiaquatic (water).  Rodents include mice, rats, squirrels, prairie dogs, porcupines, beavers, guinea pigs, and hamsters.  Rabbits, hares, and pikas also have incisors that grow continually and were once included as rodents, but are now considered a separate order, the Lagomorpha.  Still, Rodentia and Lagomorpha share a single common ancestor.  They all like to gnaw on almost anything.

Most rodents are small animals, and use their sharp incisors to gnaw food, excavate burrows, and defend themselves.  Most eat seeds or other plant material, but some have varied diets.  They tend to be social animals and many species live in societies with complex ways of communicating with each other.  Mating among rodents can vary from monogamy, to polygyny, to promiscuity.  Many have litters of underdeveloped, altricial young, while others are precocial (well developed) at birth.  The rodent fossil record dates to the Paleocene and greatly diversified in the Eocene, spread across continents, and even crossing oceans.  Rodents reached both South America and Madagascar from Africa and, until the arrival of Homo sapiens, were the only terrestrial placental mammals to reach and colonize Australia.  This is one group that seems to spread even without the aid of human carelessness.

Thoughts:  Rodents have been used as food, for clothing, as pets, and as laboratory research animals. Species like the brown rat (Rattus norvegicus), the black rat (Rattus norvegicus), and the house mouse (Mus musculus), are serious pests, eating and spoiling stored food and spreading diseases.  The Black Death (Bubonic Plague) is thought to have spread to Europe from Crimea by fleas living on black rats that traveled on Genoese slave ships.  There is evidence that once it came ashore, the Black Death was largely spread via aerosols which a pneumonic plague enables.  While this plague transmitted a bacterium (Yersinia pestis), the covid virus uses a similar aerosol spread to move from host to host.  Distancing and masks would have been just as effective in the Middle Ages as it could be today.  Follow the science.  Change is coming and it starts with you.