Ratastic News week “Rat Detective Academy and Crispy Snacks” Edition

David Bennett

It’s “back to school” season, and in this edition, we’ll be taking a look at DC’s Rat Academy, a detective who uses rat DNA to track where they go around cities, and in the true spirit of summer, when you fire up the grill, and slap on your big, juicy steaks, we advise not slapping on a big juicy rat because flame broiled or not, we don’t think roasted rat is good for your health!   We’ll travel to Cambodia where they don’t turn down a good flame broiled rat on the street!  Although it might be a good sideline for some extra dough and a novel way to cut down the rat population, rat on a stick won’t be featured at your local county fair!


Last week’s quiz question! What recent discovery of rat puts the sizable brown rat to shame both in size and ferocity?

Answer:  On average, the brown rat is about 16 inches long (including its tail) and weighs less than a pound. If a rat lives near a steady food source, like a dumpster, it can grow to be 20 inches long and weigh 2 pounds. But that’s tiny compared to the Bosavi woolly rat, which was discovered in 2009 by a BBC expedition to an extinct volcano in Papua New Guinea. The 32-inch-long beast weighed more than 3 pounds and showed no fear of humans. It’s thought to be one of the biggest in the world, and it’s a “true rat, the same kind you find in the city sewers,” mammalogist Kristofer Helgen told the BBC. Don’t worry about meeting it on the street, though: The rat, which is believed to belong to the genus Mallomys, lives only in the area of the volcano.   

To review images of the Bosavi Woolly rat use this link


This week’s quiz question: What species of rat is heavily influenced in activity based on the amount of moonlight it is exposed to?


DC Rat Academy Trains Students in Rat Control on the Front Lines

The DC health department has an annual 2-day Rat Academy where students come from all over the

country to learn how to do more than set traps for rats—they learn rat behavior to better control them. This year’s featured instructor was Bobby Corrigan, an urban rodentologist and renowned rat behavior expert. The students are property managers, private exterminators, and local government employees, and they don’t just sit in a classroom and learn theory.  They enter enemy territory—alleys, parks and restaurants to examine rats and rat behavior up close.   The Washington Post adds:“The annual two-day academy came as rodent complaints reach record highs in the District of Columbia.   The city received more than 6,000 rat complaints to its 311 service request number last year, which rose from about 5,000 in 2017. After experimenting with dry ice and solar trash cans, city officials are now testing sterilization as the newest weapon in their arsenal. It’s been tried elsewhere, including New York City,with some success.”    At the rat academy, besides rat behavior, students learn how to spot signs of infestation and how to get permits for applying pesticides.  The rat academy was transferred closer to the front lines near a row of restaurants, which also has lots of trash, which are great conditions for rodents.  DC is trying a pilot program of bait box placement with


birth control in 9 locations around the city, a sweet, fatty liquid that rats like.   Some rats like it so much they try to eat the container.    The city will be recording data on the results of the rat birth control; meanwhile, at the academy, students learned to identify factors that help the rats to thrive.  DC’s issue is that rat control measures aren’t streamlined—no single entity is in charge of rat abatement and businesses hire a variety of pest control companies that operate independently from the city government.    Education is an integral part of rat control programs and we applaud this program as well as the NYC Rat Academy!


The Sherlock Holmes of Rat Control Uses Rat DNA to Track Where They Go in Cities

Kaylee Byers is the regional deputy director at the British Columbia

node of Canadian Wildlife Health Cooperative and a PhD candidate in interdisciplinary studies at the University of British Columbia.  But don’t let the academic chops fool you—she’s trapped over 700 rats and tracks rats using their DNA.  In an article entitled “It’s Surprisingly Hard to Find Out How Rats Move Through Cities,”she details how she uses rat DNA to see where they go and how far they travel which could be useful in the application of rat abatement programs.   She writes, “Take a trip to a city almost anywhere in the world and odds are that you will find rats. Rats are infamous for traveling with us across the globe and yet, until recently, there was very little information on how rats move within cities. As someone who has trapped more than 700 rats, I can tell you that this lack of information is partly because rats are notoriously difficult to study. For other wildlife species, you can track movement by trapping an animal, tagging it with something like a numbered ear tag, recapturing that animal later on and then measuring the distance between traps. But rats are wary of traps, and very few rats will re-enter them more than once.

To get around issues of trapability, researchers can use GPS technologies. This approach still involves wrangling rats to affix GPS tags, but advances in GPS technologies allow for data to be transmitted to the researcher remotely without having to catch the animal again. In fact, miniaturization of tags has allowed us to attach GPS tags to rats. But we’ve learned that GPS tags are tricky to use with urban rats because they will remove them and satellite signals are obstructed in cities. Thank you, next?” 

Collecting rat DNA and sequencing it to find similarities and differences in individual rats enables researchers to track rats on a finer scale.  They can identify groups of relatives, which often live in close proximity to each other. Byers explains,  “In Vancouver, most relatives are within approximately 50 meters of each other and relatedness tends to decrease past 250 meters; on the whole, rats probably don’t move very far. However, some rats travel further afield. In Baltimore, one rat was estimated to have moved up to 11.5 kilometers. These migrant individuals can be identified because their genetic information assigns them to a group of individuals in a different location than to the one in which they were caught.  Thanks to genetics, we have come to understand that while rats typically move about the space of a city block, they move further than was estimated by observational methods. This is useful to know because it can help inform how we address rat-associated concerns.”  This enables researchers to also track rat-borne pathogens.  “Rats carry a number of disease-causing organisms that can be transmitted to people. Many of these are spread among rats and to people through close contact with affected rats and their urine or feces. In Vancouver, where rats rarely move between blocks, we would expect that the pathogens they carry would be restricted as well, due to few opportunities to spread. And that’s what we see. Some blocks have many rats carrying a particular pathogen, while a neighboring block may have few or no affected rats. This is important because it suggests that actions that disrupt the normal patterns of rat movement could affect pathogen spread. To remove rat-associated disease risks, efforts have focused on eliminating rats altogether, but this approach has been largely ineffective. This is partly because we fail to appropriately scale our control response. Most control efforts are enacted at a single property. If we look to the DNA, however, we see why that approach won’t cut it. Rats and rat colonies are often not restricted to a single property. For control efforts to be effective, they must encompass the genetic group, termed an eradication unit. The scale of the unit varies by location due in part to barriers to movement such as roadways or rivers. For example, in Vancouver a genetic cluster of related rats occupies an entire block, or spans several blocks. By comparison, researchers have found that an eradication unit might encompass an entire “valley” in Salvador, Brazil.” In our quest to be smarter than the rats we can find  out some pretty interesting things that not only pays homage to the sheer intelligence of the rats but also helps us focus our rat control methods to be most effective rather than putting traps and poison willy-nilly.    Maybe DNA is the way to go in order to most effectively control rats!


Rat on a Stick in Cambodia is a Cheap and Tasty Meal You Can Buy from a Street Vendor!

The next time you travel to Cambodia, and you want a cheap snack, visit the local rat on a stick vendor! (Maybe you shouldn’t.)   In the 1970’s, during the Khmer Rouge regime, people ate rats, frogs and insects as a way to survive. Now they’re just a crispy, tasty (?) snack.   CNA English version reportsthat vendor Ma Lis has cooked up a real hit: “Vendor Ma Lis says the snack has grown in popularity since she launched her stall more than a decade ago and sold just a few kilograms a day.

Today, she can net daily sales of around 20 kilograms, making brisk business from van-loads of travelling Cambodians and the occasional curious foreigner. The holiday season also spells bad news for the field rodents – Ma Lis can sell up to 180 large rats a day on the Cambodian New Year or water festival. Dismissing any health concerns one might have about eating her unconventional treat, Ma Lis says her rodents are caught from rice fields and are good for you. “These rats are healthier than pork and chicken… they eat lotus roots and rice grains,” she says, as she flips the barbecued bodies on the grill.”  Now the question we know you are dying to ask—what does it taste like?   Pork? Chicken? Beef?   Opinions seem to vary.   The band “Tastes Like Chicken” might have an opinion too—everything tastes like chicken. But at a quarter for the small rats and 1.25 for the larger ones, whether it tastes like chicken, beef or pork isn’t important when the price is right!


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Tags: British Columbia, Canada, Exclusion, Integrated Pest Management, IPM, Norway rats, NPMA, NWCOA, NYPMA, Pest management, Pest Management Canada 2019, Pest Proofing, PestWorld2019, Public Health, Public housing, Quality Assurance, Rodent exclusion, Rodexit

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