Scientists in New York City discover a valuable method to track rats

Date:  September 17, 2019

Source:  Oxford University Press USA

A new paper in The Journal of Urban Ecology, published by Oxford University Press, finds that rats can be baited to, or repelled from, locations using pheromones found in the scents of other rats.

Rats cost the world's economy more than $300 billion a year. In addition to causing fines and business closures, rats spread disease, start fires, and disable motor vehicles. In Manhattan alone, rodent activity has been found in 23% of all restaurants. Despite these impacts, little is known about the behavior of urban rats, whose behaviors differ from that of laboratory rats. This lack of information is due to several factors, including the difficulty of releasing pest animals back into cities after capturing and identifying them, the reluctance of property owners to provide access to researchers, and rat control programs.

Over a one year period, researchers trapped and implanted microchips in city rats in a waste recycling center in Brooklyn, New York. To overcome issues in using GPS to track movement in dense urban environments, they utilized radio-frequency identification sensors. Male and female scents were then placed on, or near, these sensors and replaced every two weeks. To determine whether risk impacted the findings, researchers positioned these devices in sheltered, safe areas that rats were familiar with and also in more risky, open environments where rats were vulnerable to predation.

Rats reacted differently to male and female scents. In general, when rats responded to sensors with male-scents, risk was unimportant. Rats briefly visited male scents equally in exposed and sheltered areas, and then stayed away. Female scents, however, were visited significantly more often than male scents (0.2 visits/day compared to 5.02 visits/day). This implies that attractants may be more useful near sheltered areas while deterrent scents may be more useful in exposed areas where animals are vulnerable to predators. These findings address a knowledge gap about rat-scent preference that could assist in urban wildlife management tools, such as the deployment of baits or immuno-contraceptives.

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Living with rats involves understanding the city as an ecosystem

JULY 11, 2019

by Chelsea Himsworth, The Conversation

Rats! They eat our food, chew through our property and spread all sorts of nasty diseases. And they are gross (right?), with those naked tails and quick, unpredictable movements. Rats invade our homes—our castles!—the one place where we should be safe and in control.

Over the millennia that we have lived with them, rats have proven themselves virtually impossible to expunge. They are so adaptable that they can exploit and infest virtually every corner of our cities. They avoid traps and poisons and reproduce at such a staggering rate that extermination attempts usually end up being a game of whack-a-mole… or, rather, whack-a-rat.

Is it any wonder that many cities seem to be plagued by rats? Or do the cities themselves bear some responsibility for their rat problems? This is what I have been exploring over the past 10 years as a wildlife and public health researcher with the Canadian Wildlife Health Cooperative and the University of British Columbia.

Challenges of managing urban rodents

For the most part, when it comes to dealing with rats, cities have it all wrong. For example, rat-related issues are addressed using a hodgepodge of unrelated policy and programming. At best, municipal leadership is highly fragmented; at worst, it's absent altogether.

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Drones Are Dropping Poison on Recently Re-invaded Rats in the Galapagos – via Herp Digest

Scientists hope that they've built a better rat trap with flying poison distribution. Eliminate major predator of tortoise eggs and juveniles and bring back ex-situ breeding on islands.

By David Grossman 1/24/19 Source - Wired

ISLAND CONSERVATION

For as long as people have been creating organized communities, rats have been there to pick off the remains. As an invasive species, they're practically unparalleled in their success, much to the chagrin of the people living with them. But when they recently re-invaded Ecuador's Galápagos National Park, a new weapon proved extremely effective in the fight: drones.

While the Galápagos islands are historic for being the site of Charles Darwin's discoveries about evolution, other visitors have been less helpful. Rats first came to the Galápagos along with pirates or whalers sometime in the 17th or 18th century. While the exact timeline is unknown, they've done their damage over the years. They've curbed the births of tortoises and have laid waste to local fauna.

The rats were beaten back from the tiny North Seymour Island in 2007, but they found their way back ten years later. Since then, the challenge has been how to attack the rats without inflicting further damage on a very delicate ecosystem.

Drones provided an ideal solution. Painted blue to make them less noticeable to birds, they dropped poison pellets wherever rats were spotted. "The use of drones is more precise," says Karl Campbell, the South American director of the nonprofit group Island Conservation, in a press statement. "It also increases feasibility, and reduces eradication costs of invasive rodents in small and midsize islands worldwide.”

Earlier this month, two six-rotor drones began lacing North Seymour and a nearby islet with rat poison. Each drone could carry 44 pounds (20 kilograms) worth of poison and fly around for 15 minutes. While one of the drones suffered a mechanical difficulty, according to Nature, they were still able to cover half the island in valuable poison. The breakdown even afforded the chance for an experiment—workers spread the rest of the poison over the island by hand, allowing for an evaluation of the drones.

Island Conservation - A pilot remotely operating a drone as it flies over North Seymour Island.

Drones can't cover every part of the land—for some remote islands, only a helicopter will do. But as Campbell tells Nature, “you have to have a helicopter for a month, sometimes shipped by boat. Your expenses very quickly add up.” Drones allow for more flexibility at a cheaper price.

Craig Morley, an invasive-species specialist at the Toi Ohomai Institute of Technology in Rotorua, New Zealand, says that the drones have a chance to change how scientists view conservation work. “You used to be able to see your opponent. Now, you just a press a button and you fire a missile,” he tells Nature, drawing a comparison between scientific and military drones. “You become a little bit detached from the reality that you have killed something or somebody over there.”

While it is important to keep that detachment in mind, it is unlikely anyone in the Galápagos will miss the rats too much.

Rats and pigeons 'replace iconic species'

By Helen Briggs BBC News

5 December 2018

The modification of land for farming and building cities is favouring the same species everywhere, according to a new study.

Animals like rats and pigeons are taking over from less common ones, which can survive only in certain habitats, say scientists.

Researchers looked at 20,000 animals and plants in 81 countries.

They found that species occupying a large area tend to increase in places where humans use the land.

However, fauna and flora that occupies a small area is lost.

"We show around the world that when humans modify habitats, these unique species are consistently lost and are replaced by species that are found everywhere, such as pigeons in cities and rats in farmland," said Dr Tim Newbold, a research fellow at University College London.

Rats, mice, sparrows and pigeons are examples of species with wide ranges that do well when natural habitats are replaced with farmland and cities, he said.

However, the "narrow-ranged losers" include animals and plants which may have great cultural value, such as rhinos and tigers.

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World's first human case of rat disease found in Hong Kong

September 28, 2018

A Hong Kong man has developed the world's first ever human case of the rat version of the hepatitis E virus, according to new research from one of the city's leading universities.

There had previously been no evidence the disease could jump from rats to humans, the University of Hong Kong said Friday, warning the discovery had "major public health significance".

"This study conclusively proves for the first time in the world that rat HEV can infect humans to cause clinical infection," the university added.

Rat hepatitis E virus is very distantly related to human hepatitis E virus variants, HKU said.

The disease was found in a 56-year-old man who persistently produced abnormal liver function tests following a liver transplant.

He could have contracted the illness through food infected by rat droppings, researchers said, according to details of the findings reported in the South China Morning Post.

The man lived in a housing estate where there were signs of rat infestation outside his home. He is now recovering after being treated for the virus, the SCMP added.

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Rats trail behind shrews, monkeys, and humans in visual problem solving

Work could have important implications for translational research

Date:  July 12, 2018

Source:  Society for Neuroscience

Summary:

Rats take a fundamentally different approach toward solving a simple visual discrimination task than tree shrews, monkeys, and humans, according to a comparative study of the four mammal species. The work could have important implications for the translation of research in animal models to humans.

Rats take a fundamentally different approach toward solving a simple visual discrimination task than tree shrews, monkeys, and humans, according to a comparative study of the four mammal species published in eNeuro. The work could have important implications for the translation of research in animal models to humans.

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Pacific rats trace 2,000 years of human impact on island ecosystems

June 4, 2018, Max Planck Society

Chemical analysis of the remains of rats from archaeological sites spanning the last 2000 years on three Polynesian island systems has shown the impact of humans on local environments. The analysis by an international team of scientists allowed the researchers to reconstruct the rats' diets—and through them, the changes made by humans to local ecosystems, including native species extinctions and changes to food webs and soil nutrients.

The Earth has entered a new geological epoch called the Anthropocene, an era in which humans are bringing about significant, lasting change to the planet. While most geologists and ecologists place the origins of this era in the last 50 to 300 years, many archaeologists have argued that far-reaching human impacts on geology, biodiversity, and climate extend back millennia into the past.

Ancient human impacts are often difficult to identify and measure compared to those happening today or in recent history. A new study published in the Proceedings of the National Academy of Sciences by researchers at the Max Planck Institute for the Science of Human History in Jena and the University of California, Berkeley advances a new method for detecting and quantifying human transformations of local ecosystems in the past. Using state of the art methods, researchers searched for clues about past human modifications of island ecosystems from an unusual source—the bones of long-dead rats recovered from archaeological sites.

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Neuroscientists find first evidence animals can mentally replay past events

Discovery of episodic memory replay in rats could lead to better treatments for Alzheimer's disease

Date:  May 10, 2018

Source:  Indiana University

Neuroscientists at Indiana University have reported the first evidence that non-human animals can mentally replay past events from memory. The discovery could help advance the development of new drugs to treat Alzheimer's disease.

The study, led by IU professor Jonathon Crystal, appears today in the journal Current Biology.

"The reason we're interested in animal memory isn't only to understand animals, but rather to develop new models of memory that match up with the types of memory impaired in human diseases such as Alzheimer's disease," said Crystal, a professor in the IU Bloomington College of Arts and Sciences' Department of Psychological and Brain Sciences and director of the IU Bloomington Program in Neuroscience.

Under the current paradigm, Crystal said most preclinical studies on potential new Alzheimer's drugs examine how these compounds affect spatial memory, one of the easiest types of memory to assess in animals. But spatial memory is not the type of memory whose loss causes the most debilitating effects of Alzheimer's disease.

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Rats sniff out TB in children

Research shows that rats can detect tuberculosis in children with higher accuracy than standard microscopy tests

Date:  April 9, 2018

Source:  Springer

Rats are able to detect whether a child has tuberculosis (TB), and are much more successful at doing this than a commonly used basic microscopy test. These are the results of research led by Georgies Mgode of the Sokoine University of Agriculture in Tanzania. The study, published by Springer Nature in Pediatric Research, shows that when trained rats were given children's sputum samples to sniff, the animals were able to pinpoint 68 percent more cases of TB infections than detected through a standard smear test. Inspiration for investigating the diagnosis of TB through smell came from anecdotal evidence that people suffering from the potentially fatal lung disease emit a specific odour. According to Mgode, current TB detection methods are far from perfect, especially in under-resourced countries in Sub-Saharan Africa and South East Asia where the disease is prevalent, and where a reasonably cheap smear test is commonly used. Problems with this type of test are that the accuracy varies depending on the quality of sputum sample used, and very young children are often unable to provide enough sputum to be analysed.

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Norway rats trade different commodities

Date:  February 1, 2018

Source:  University of Bern

Summary:

Researchers have shown for the first time in an experiment that non-human animals can also exchange different kind of favors. Humans commonly trade different commodities, which is considered a core competence of our species. However, this capacity is not exclusively human as Norway rats exchange different commodities, too. They strictly follow the principle "tit for tat" -- even when paying with different currencies, such as grooming or food provisioning.

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Black Death 'spread by humans not rats'

By Victoria GillScience correspondent, BBC News

15 January 2018

Rats were not to blame for the spread of plague during the Black Death, according to a study.

The rodents and their fleas were thought to have spread a series of outbreaks in 14th-19th Century Europe.

But a team from the universities of Oslo and Ferrara now says the first, the Black Death, can be "largely ascribed to human fleas and body lice".

The study, in the Proceedings of the National Academy of Science, uses records of its pattern and scale.

The Black Death claimed an estimated 25 million lives, more than a third of Europe's population, between 1347 and 1351.

"We have good mortality data from outbreaks in nine cities in Europe," Prof Nils Stenseth, from the University of Oslo, told BBC News.

"So we could construct models of the disease dynamics [there]."

He and his colleagues then simulated disease outbreaks in each of these cities, creating three models where the disease was spread by:

rats

airborne transmission

fleas and lice that live on humans and their clothes

In seven out of the nine cities studied, the "human parasite model" was a much better match for the pattern of the outbreak.

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Study shows genetic differences between uptown and downtown rats living in Manhattan

December 4, 2017 by Bob Yirka report

(Phys.org)—A small team of researchers from Fordham University and Providence College, both in the U.S., has found that there are small but discernible genetic differences between rats living uptown versus downtown on the island of Manhattan. In their paper published in the journal Molecular Ecology, the group describes trapping rats from one end of the island to the other, conducting genetic tests on them and outlining what they found.

New York City, like other major cities in the world, hosts a very large population of rats—in this case, mostly brown rats. Most people that live there find them to be a problem, because in addition to being destructive and carriers of disease, they are also considered to be disgusting. In this new effort, the researchers sought to learn more about the rats that live only on Manhattan Island, noting that little work has been done to understand the rats that live there.

The study consisted of trapping rats, moving north to south on the island, cutting off their tails, and using them as a source for DNA analysis—and then comparing the genomic results by geography.

The researchers report that the vast majority of the rats were descendants of rats from western Europe—brought over on ships over 200 years ago. But the analysis also revealed that the rats have been in the area long enough to have developed minor genetic differences depending on where they lived. This, the team notes, was not particularly surprising due to rat behavior—they rarely stray far from home. Nor was it surprising to see differences between the uptown and downtown rats—the two areas are separated by the commercial district, which is not particularly favorable to rats. Thus, those that live uptown have little incentive to move downtown, or vice-versa. Surprisingly, the analysis showed that there were even slight differences between neighborhoods—each had their own distinct rats. The researchers could tell, for example, by looking at an individual rat profile, if it had resided in the East or West Village.

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Study on how rats process smell may address larger issue of experiment reproducibility

May 18, 2017 by Carla Reiter 

University of Chicago psychology professor Leslie Kay and her research group set out to resolve a 15-year-old scientific dispute about how rats process odors. What they found not only settles that argument, it suggests an explanation for the much written-about "replication crisis" in some fields of science and points to better ways of designing experiments. 

Reproducible experimental results are part of the bedrock of scientific method. But a concern is that researchers, particularly in psychology and medicine, are too often unable to replicate the findings of colleagues in other labs.

This has certainly been true of understanding how rats—and by extension, possibly humans—process smell. "There was simply a disagreement in the literature," Kay said. "Different labs tried to get the same result, and they were unsuccessful."

The diverging results came from two camps, doing similar but slightly different experiments. What Kay and her group found was that while both were correct, they were asking different questions without realizing it. Their experiments were not, in fact, comparable.

Kay's group's study, published this spring in Journal of Neuroscience, shows that the disparate conclusions arise from small but crucial differences in the way the two sets of experiments were set up. By eliminating those differences, and then doing both experiments rather than only one, the group was able to tease out similarities underlying the varying results and discover a general truth about how rats smell.

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Rats and snakes beware: Arizona House OK's tiny ammo – via Herp Digest

By BOB CHRISTIE, Feb 1, 2017

           

PHOENIX (AP) — The Arizona House on Wednesday approved legislation allowing city residents to shoot rats or snakes using small-caliber guns loaded with tiny pellets.

The proposed law would allow anyone to shoot the tiny shotgun shells inside city limits, even if they aren't trying to kill a snake.

The 35-25 vote fell along party lines, with Republicans in favor and Democrats opposed to Republican Rep. Jay Lawrence's proposal. There was no discussion.

The formal vote on House Bill 2022 came a day after the House debated the bill and GOP majority lawmakers gave it initial approval over Democrats' dissent.

The proposal amends a landmark 2000 law aimed at celebratory gunfire enacted following the 1999 death of a Phoenix teen struck by a stray bullet. It adds an exception from felony charges for using the ammunition called rat- or snake shot in .22-caliber guns.

Lawrence said Tuesday that his legislation isn't about shooting reptiles or rodents, despite the definitions in his bill referring to "rat or snake shot."

"This is not a kill-animals bill, it has nothing to do with killing snakes, it has nothing to do with killing rats, cats or dogs," Lawrence said. "This is a firearms bill, strictly and totally."

Democrats worried that people would unnecessarily shoot wildlife. Even worse, they worried about unrestrained shooting within city limits.

"Generally, I think those two do not mix too well and we could see an increase of injuries to people as a result of this bill," Democratic Rep. Kirsten Engel, of Tucson, said of the proposal relaxing the ban on shooting within city limits.

The 2000 law makes it a felony to fire a gun within city limits or within one mile of an occupied structure, with exceptions for self-defense or for dispatching a nuisance animal with a permit.