Exploring the long history of rats – Worcester Telegram


Recommended by Dikshit Aryal, Published on June 17th, 2020

While we have several native species of mice in Massachusetts, we surprisingly have no native rats. Deer mice, white-footed mice, woodland jumping mice, meadow jumping mice, red-backed voles, meadow voles, woodland voles and bog lemmings scurry across the state. But we have to drive to the rocky cliffs of western Connecticut to find the closest native rat species, the eastern woodrat.

Nevertheless, somewhere within walking distance of our homes are Old World brown rats. Although theyre sometimes called Norwegian rats, they really originated in Asia. They, along with the also-alien house mouse, which invades the interiors of our homes, are now a scourge within every community. The explanation for their proliferation is simple: people throw out enormous quantities of garbage, and rats thrive on our nutritious trash.

Just a few thousand years ago, these harmful rodents had a natural, positive role in their wild, native Asia. They fed many raptors and other predators. But their ability to live and thrive among expanding, habitat-altering human populations a rather amazing species strength, if were honest has come to plague civilization.

Two species, the black and the brown rats, have, in particular, caused more human deaths than all other vertebrates combined. Just touching them can prove infectious as they are regular hosts to fleas, mites, ticks, cestodes, nematodes and trematodes.

Reproductive machines, female rats can mate with multiple males in a single day and produce up to 12 litters a year, averaging about eight babies in each one. One single pair and their mating young, which reach sexual maturity at four or five weeks, could collectively produce over a thousand rats during their first year. Living up to three years of age, that single original pair and all its breeding progeny could, without massive mortality, produce hundreds of thousands of rats.

Fortunately, local hawks, owls, foxes, mink, skunks, weasels and snakes kill huge numbers of them for dinner. And even more rats are killed by diseases like salmonellosis, tularemia, leptospiral jaundice, Haverhill fever and murine typhus fever, whenever their populations get too dense.

Surprisingly, our states first introduced rat from the Old World spread widely and was eventually eradicated but not by us or our natural controls. The black rat, Rattus rattus notorious for spreading the Black Plague came aboard ships to America, infesting Virginia by 1609 and New England by the end of the 17th Century. It would continue to jump ships from Europe and become the uncontested king of human garbage deposits, in all our Atlantic seaports. They would thankfully disappear, but not courtesy of our poisons, cats or dogs.

Around 1775, flourishing with expanding world trade, the bigger, more aggressively intolerant brown or Norway rat arrived here, established itself, and in a rodent war of historical proportions, savaged all the black rat populations throughout New England. This was the rodents version of Shermans march through Georgia.

Retired MassWildlife biologist Jim Cardoza shared that black rats were mostly gone by 1900 and fully extirpated from Massachusetts by the 1930s, though a few show up periodically and for a very short time as business continues to inadvertently reintroduce them, either from abroad or from our southern states, where they remain abundant. Just recently, some were trapped in Chelsea. Tufts infectious disease authority, Dr. Sam Telford, told me that the closest black rat populations are now in Washington, D.C. From there, south, they thrive, especially in warm seaports.

For most people, a rat is a rat, but these two warring, misplaced malefactors are very different. Black rats are smaller, more streamlined, with pointed snouts, and tails longer than their bodies. Their hair is scraggly and glossy black down their spine. Brown rats have tails shorter than their bodies and more monochromatic gray or brown hair.

Natural tree climbers in their native Asia, black rats acrobatically live mostly within the vertical aspects of our homes and buildings. Wherever theyre both encountered, brown rats drive black rats up to the highest parts of buildings. Black rats have consequently been also called roof rats.

The dominating brown rats victoriously settle into lower, flatter habitats, closer to garbage, where typically they burrow in the ground around sewers, stream banks, jetties, walls and riversides. Theres hardly a veteran Canal fisherman that hasnt encountered brown rats scurrying out from the rocks at dawn or sunset or a Blackstone carp fisherman that hasnt observed them, too, lurking along the banks. Southerners who hear a rat in their wall can bet its a black rat. Those of us here who see one come out of a hole in our yard can bet the bank that its a brown rat.

Rattus rattus cohabitation with humans goes back over 4,000 years ago especially in India, where the species has long been considered sacred. Today, the black rat is surprisingly worshipped and daily fed there with much ritual at the Karni Mata Temple of Deshnoke.

Business facilitated its transport. As far back as 3,000 years ago, the black rat began arriving in Europe via trade routes, especially for spices and silk. By the 1300s, the well-established black rat and its fleas would infest the filthy squalor of European settlements and spread the flu-like Black Plague. The bacteria, Yersinia pestis, would kill 50 million people a third of the population.

Like Covid-19, its economic impact was staggering and counter-intuitively positive in a way that no one ever envisioned. The loss and shortage of so many workers unexpectedly resulted in a subsequent increased demand for labor that significantly raised wages and elevated the status and compensation of the European worker from that time on.

The most recent catastrophic rat plague known as the Third Pandemic began in 1855 and troublesomely didnt end entirely until 1959. It originated in Chinas Yunnan province, and spread through India and Mongolia. Of the 12 million people who died, 10 million were in India. But it had intermittent pulses of massive deaths in Hong Kong in 1894, Bombay in 1896, Honolulu in 1899, Sydney in 1900, Cape Town in 1901, Shenyang in 1911, and Los Angeles in 1924. Deaths were recorded in England, where a great outbreak never emerged.

Shenyang, China, though, stood out for what would prove historically lethal. With 60,000 people dying, its fatality rate among those infected was a staggering 100%.

The brown rats, Rattus norvegicus, that infest Massachusetts now came here from China. Growing up in the three-decker neighborhood just above Water Street, I saw many brown rats attracted to the discarded trash from the neighborhoods bakeries, restaurants and produce stores. Their population expanded dramatically up the hill towards Providence Street once the explosives started, breaking through the ledge to build Route 290 during the late 1950s. But today, you can find brown rats in our fashionable West Side neighborhoods, too. Getting rid of them isnt easy.

Theyre hyper-cautious and overly-sensitive to light. Late afternoons, they begin to emerge. Their eyesight is keen but only exceptional out to about three feet. Beyond that, they rely on their amazing ability to detect the slightest motion. They can reflexively react to any sudden movement up to about 30 feet away. To shoot them with a pellet gun, youve got to be quiet and still.

Most homeowners who dont call in an exterminator will try rat poison pellets. But rats are notoriously bait-shy, typically avoiding anything new placed in their path. Successful trappers learn to first cover un-set traps for several days with bait to accustom them to feed comfortably. Once the rats feed at ease, exterminators will set out many baited traps ready to spring, hoping in one or two nights before they get wary to kill the majority of them.

Unexpectedly, these same rats have been bred in captivity for our benefit. Albino mutants of the brown rat and house mouse have both helped save millions of human lives via their role in scientific experiments for medicine. Theyve also been bred as pets, surprisingly demonstrating both their intelligence and capacity for docile affection.

Dr. Tom French and Cardoza are currently co-writing Mammals of Massachusetts. In a recent conversation on the black rats extirpation in our state, all Dr. French had to say was Good riddance!! For most people, a good rat will always be a dead rat.

Contact Mark Blazis at markblazissafaris@gmail.com.

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Exploring the long history of rats - Worcester Telegram

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