City Environments are Making Rats Larger

Author: Kurt Treftz, Cascade Pest Control

Giant Rats—Wild Urban Animals, including rats, mice, opossums, and others are growing larger!

Yes, those stories of huge rats in our city environments have proven to be true.  And it doesn’t stop with rats either.  The study, done by the Florida Museum of Natural History, shows that wild mammals living in urban environments are steadily growing larger. 

city rats getting larger

These shrews are part of the Florida Museum’s mammal collection. Researchers can use historical specimen data to track how animals have changed over time as humans modify the environment. FLORIDA MUSEUM PHOTO BY NATALIE VAN HOOSE

Larger Rats in the Seattle Region

So, those stories of people claiming they saw a giant rat in Seattle, Tacoma, Bellevue or Bellingham may not have been exaggerated as much as we thought.

The study’s results were a surprise because scientists expected the ‘urban heat island effect’ to result in smaller, not larger, animals.  Researchers gathered data from 80 cities in North America, taking 140,500 measurements in account.  The conclusion was that city-dwelling mammals, including Norway rats and Roof rats, were longer and heavier than those found in rural areas.  The Florida Museum’s article wasn’t clear where the phenomena stopped and may extend into suburban areas being as homes and pavement retain heat better than more natural environs such as rural and wilderness areas.

The study’s lead author, Maggie Hantak, makes the point that we can’t assume a classic theory known as Bergman’s Principle—where mammals in colder climates get larger and those in warmer climates get smaller—to be correct. 

What does this mean for rat control and mouse control?  It certainly indicates that old-world rats are doing quite well living amongst humans.  They not only continue to thrive in numbers but are also getting larger.  This probably indicates rats will consume more food and gnaw slightly larger holes when entering homes and other structures. 

Home and business owners in the Greater Seattle/Tacoma and Puget Sound region can help curb the rat and mouse population by doing a few simple things:

  • Don’t leave uneaten food in outdoor dog or cat dishes.  This is an invitation to rats and mice in the neighborhood.
  • Place bird feeders so that spilt seed is contained and is frequently cleaned up.  ANY spilt bird seed will attract rodents, not just the cute squirrels you may see during the daytime!
  • Regularly clean out the grease that is collected within barbecues.  We love our barbecues, but it takes more than just clearing the little grease trap.  Occasionally, we also need to lift the grates and—using a spatula—scrap the grease and fallen scraps down into the grease collector.  Rats love BBQ’s as they are an ample supply of fat and some protein.

These are but a few measures that can be taken to ward off our giant rats.  Optimum rodent control—whether it’s rats or mice—includes professional pest control.  Cascade Pest Control can inspect and assess your home or business for rodent control, provide you with more specific rodent-proofing recommendations, and a maintenance service that provides a perimeter defense against constant presence of rats and mice.

Call Cascade Pest Control at 888-989-8979 for professional mice or rat control services, today!

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