How Did Non-Native Rats Become Abundant In Upstate New York? And Why Are They Unusually Aggressive Pests?

How Did Non-Native Rats Become Abundant In Upstate New York? And Why Are They Unusually Aggressive Pests?

While the Big Apple is well known for its thriving rat population, little attention is paid to the alarmingly high rate of rat infestations in upstate New York. Perhaps it is not surprising to non-residents to learn that rat infestations are by no means uncommon in cities like Rochester, Buffalo and Albany. But what may catch most outsiders by surprise is that all three of these cities made the top 40 list of the most rat-infested cities in the United States. Although rats are abundant in upstate New York, the common Norway rat is not a native species within North America. Despite their common name, Norway rats are not native to Norway; instead, the species hails from the other side of the world in northern China and southern Russia, and their alien status in the US may explain why so many American are disgusted by the critters.

According to researchers, the now commonly spotted Norway rat in New York began to spread around the world only three centuries ago. Once these rats arrived in new territoires, such as Europe and Siberia, human populations fled their homeland due to the disgust that the rats incited in natives. However, researchers believe that this harsh response to the rat’s presence in foreign regions was ultimately motivated by an instinct to avoid disease, as Norway rats carry disease causing pathogens that they acquire from filthy environments that are rich in human and animal waste.

During the 1700s, Norway rats arrived in New York and other New England states via early seafaring vessels that departed from Russia. These first arrivals quickly proliferated and claimed New York as their own, as they violently fought off later Norway rat immigrants that arrived in the state from European ships. In other words, the current Norway rats of New York are of purebred Asian stock, and to this day, they do not take kindly to foreign visitors that spent a long period of time in Europe.

This theory is well supported by comparing genetic data collected from Norway rats in New York with all other Norway rats around the world, and it also explains why rats in all areas of New York are relatively aggressive and quick to fight. Researchers have found that the Norway rats of New York bear scars, lost teeth and lacerated flesh, indicating frequent fights with other animals. Although New York rats may also be aggressive toward humans, they at least help to prevent new rat-borne diseases from being introduced into the state due to their habit of not accepting foreigners.

Have you ever had an encounter with an aggressive rat?

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