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Coyotes-Wolves-Cougars.blogspot.com

Grizzly bears, black bears, wolves, coyotes, cougars/ mountain lions,bobcats, wolverines, lynx, foxes, fishers and martens are the suite of carnivores that originally inhabited North America after the Pleistocene extinctions. This site invites research, commentary, point/counterpoint on that suite of native animals (predator and prey) that inhabited The Americas circa 1500-at the initial point of European exploration and subsequent colonization. Landscape ecology, journal accounts of explorers and frontiersmen, genetic evaluations of museum animals, peer reviewed 20th and 21st century research on various aspects of our "Wild America" as well as subjective commentary from expert and layman alike. All of the above being revealed and discussed with the underlying goal of one day seeing our Continent rewilded.....Where big enough swaths of open space exist with connective corridors to other large forest, meadow, mountain, valley, prairie, desert and chaparral wildlands.....Thereby enabling all of our historic fauna, including man, to live in a sustainable and healthy environment. - Blogger Rick

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Tuesday, August 13, 2019

"Urban Norway and black rats are the source of a number of pathogens responsible for significant human disease and death in cities around the world"............."These pathogens include zoonotic bacteria, viruses and parasites"............."City rats typically move about the space of a city block".............. "To remove rat-associated disease risks, efforts have focused on eliminating rats at a single property"............... "However, this approach has failed because 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"..............."The common thread was natural or man-made barriers that kept the groups of rats apart"............... "And that is good information because it offers city planners ammunition for controlling rat populations"............. "That is the ultimate goal, after all, in most rat studies"............"Instead of taking the whack-a-rat approach to eradication, it might make more sense to learn how humans make life easier for the rats, versus what makes it more difficult for them to survive among us and then utilize control measures across the entire geographical unit of those genetically similar rat populations"

https://phys.org/news/2019-08-rat-dna-uncover-rats-scurry.html

Rat detective uses DNA to uncover how rats scurry around cities

It's dark and I'm parked in an alley near a lopsided compost bin. I have a notepad, binoculars and a lukewarm cup of coffee—everything needed for a successful stakeout. I am waiting for them
They appear approximately one hour before dawn, skittering from dumpster to dumpster along old paths they have worn down with time. I am trying to track their movements, to understand how far they go and how often. But it's clear to me that the traditional detective approach isn't going to work. There are too many and they move in places where I can't follow. I'll have to track them a different way—I'm going to need some rat DNA.




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.
Slippery little fellas
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 , 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 trappability, 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?




An alternative to these approaches involves collecting rat DNA. Chances are you've heard of companies like 23andMe that track your global ancestry by sequencing DNA from your saliva. This approach looks at similarities and differences in the genetic codes of individuals to make inferences about how similar your DNA sequence is to that of other people in the database. This can also be applied to rats. Indeed, researchers have used genetics to track the migration of rats globally. But how can this information help us to understand and address rat-associated issues?
Staying close to home
When sampled across a city, we can trace rat movement at a finer scale. Over the past 10 years, there has been an increase in the number of rat movement studies using genetics. By looking at relatedness of individuals based on genetic similarity, we can identify groups of relatives. We've found that relatives are often in  to each other.
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  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.
Pathogens on the block
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 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.
From my vantage point in the alley, I am struck by the power of genetic sequencing to help us answer challenging questions. Instead of viewing each rat independently, I begin to see them as interconnected groups of relatives scurrying along the pavement. I wonder if any are outsiders, migrants from another block.
I check my bag and realize that something's missing. Tomorrow I'll be back with what I need for DNA collection: my Rat Detective Toolkit 2.0.

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