Rat

July 27, 2023

Since I addressed the decimation of the bird population by outdoor cats, it is only fair to address another destructive enemy (along with humans) faced by the bird population, the rat.  Several days ago, I was sitting in my car having just exited the store.  There was a small hedge interspersed with trees that lined the grassy area of the parking lot and separating the lot from the ditch which held a small runoff stream.  As I turned the car on the frantic activity of a Northern mockingbird (Mimus polyglottos) caught my eye.  The bird was madly diving into the 2 foot (.6 m) high hedge.  I watched as the bird repeatedly dove into the bush.  I could not figure what was causing this activity until the bird neared one of the openings along the hedge.  That is when I saw a rat scurry across the opening with the bird diving to drive it away.

When I went online, I found the term rat refers to various medium-sized, long-tailed rodents.  Different species of rats are found throughout the order Rodentia, but stereotypical rats are found in the genus Rattus.  The Ancient Romans did not differentiate between rats and mice, instead referring to the former as mus maximus (big mouse) and the latter as mus minimus (little mouse).  Today a rat is typically distinguished from a mouse by its size.  Usually, the common name of a large muroid rodent will include the word “rat”, while a smaller muroid’s name will include “mouse”.  There are 56 known species of rats in the world, but the best-known rat species are the black rat (Rattus rattus) and the brown rat (Rattus norvegicus) both of which originated in Asia.  Rats are bigger than most Old World mice, which are their relatives, but seldom weigh over 17 1⁄2 ounces (500 grams) in the wild.  When the rat is introduced into locations where they did not previously exist, they can wreak grate amounts of environmental harm.  The black rat (or ship rat) is considered one of the world’s worst invasive species and has been carried as a stowaway on seagoing vessels for millennia.  The brown rat (wharf rat) has similarly been carried as a stowaway worldwide in recent centuries.

The ship and wharf rat has contributed to the extinction of many species of wildlife, including birds, small mammals, reptiles, invertebrates, and plants, especially on islands.  A rat is omnivorous and capable of eating a wide range of plant and animal foods and has a very high birth rate.  When introduced to a new area, they quickly reproduce to take advantage of the new food supply.  As the rat spread to isolated islands they preyed on the eggs and young of forest birds, which often have no other predators and no innate fear of predators.  Some experts think rats are to blame for between forty percent and sixty percent of all seabird and reptile extinctions, with ninety percent of those occurring on islands.  That means even though the rat may be responsible, humans accidentally introduced the rat to these new areas.

Thoughts:  While once considered a modern myth, the rat flood in India occurs every fifty years as armies of bamboo rats descend on rural areas and devour everything in their path.  Rats (and their fleas) have long been considered the main source of spread for the Bubonic Plague, even though recent studies show rats alone could not account for the rapid spread of the disease through Europe in the Middle Ages.  Unsanitary conditions and refusal to bathe and wash clothes could have had something to do with a flea outbreak which carried the pathogen.  The CDC lists nearly a dozen diseases directly linked to the rat.  “Rat” in the English is often an insult or signifies someone as an unscrupulous character.  An inflatable rat, or union rat, is a giant inflatable shaped like a cartoon rat, commonly used in the US by protesting or striking trade unions as a sign of opposition against employers or nonunion contractors to call public attention to companies employing nonunion labor.  Perhaps the mockingbird was justified to drive the rat away.  Act for all.  Change is coming and it starts with you.