Poison meant for city rats is killing wildlife in South Africa

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Poison meant for city rats is killing wildlife in South Africa

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20.05.2019 | ByBrooks Hays

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Postdoctoral research fellow Laurel Serieys poses with a caracal kitten in Cape Town's Table Mountain National Park. Photo by Laurel Serieys/University of Cape Town

- Rat poison intended to kill rats in Cape Town (and many other big cities), South Africa, is seeping into the surrounding environment and harming local wildlife, including caracals, mongooses, otters and owls.

Scientists at the University of Cape Town measured the levels of rat poison compounds in liver and blood samples from 41 animals in Table Mountain National Park. The tests showed 92 percent of caracals in the park have been exposed to anticoagulant rat poisons. Caracals look similar to mountain lions and are sometimes called African lynx. In total, scientists found 81 percent of tested animals had been exposed to rat poisons.

According to the new study, animals in Table Mountain National Park aren't consuming rat poisons directly. Rat poisons are designed to kill rodents slowly over a period of days. When the rats get sick, they become easy targets for hungry predators. When poisoned rats are eaten, the toxic compounds can travel up the food chain.

"We detected at least one of the four most toxic rat poison compounds, all available in over-the-counter products, in six of the seven species tested," lead researcher Jacqueline Bishop said in a news release.

Researchers found concentrations of rat poisons were highest among caracals living near vineyards.

"Vineyards in Cape Town don't use rat poisons to protect their vines, but they do host restaurants, spas and hotels and occur adjacent to dense residential areas where rat poisons are widely used. Caracals regularly hunt in vineyards and it is here that they are likely to be exposed to poisoned rats, in and around urban structures," Bishop said.

Bishop and her colleagues focused their testing on caracals, but also tested several other species they found hit by cars. Positive tests among otters suggest the toxins are making their way into local waterways.

This isn't the first time scientists have documented the movement of rat poison up the food chain. In California, researchers have measured rat poison toxins in wildlife specimens living near places where illegal marijuana farming is a growing problem. Marijuana farmers use rat poisons to protect their crops.

"There is mounting evidence globally that rat poisons are a critical threat to wildlife, including threatened and endangered species," said researcher Nikola Okes. "To really understand this problem locally has taken support from the public, from South African National Parks and the City of Cape Town in reporting the locations of animals hit by cars so they could be included in our study."

Caracals, the study's main focus, are threatened by habitat loss and poaching. Researchers hope their work, published this week in the journal Science of The Total Environment, will inspire the use of more eco-friendly rodent control methods.

"As consumers, we need more eco-friendly alternatives to rat poison and the simplest solution is well within everyone's reach -- improve the management of waste which attracts rats in the first place," Okes said.

https://www.upi.com/Science_News/2019/0 ... 558360117/


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Re: Poison meant for city rats is killing wildlife in South Africa

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And owls! :yes:


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Re: Poison meant for city rats is killing wildlife in South Africa

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\O


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Re: Poison meant for city rats is killing wildlife in South Africa

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Scientists: How we found out that rat poisons are killing wildlife in Cape Town

Laurel Serieys and Jacqueline Bishop | 30.05.2019

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Wildlife near cities face many dangers. Some are easy to detect, such as when new developments destroy natural habitat. Others are less obvious.

For example, rat poisons are a useful tool for controlling a common household problem. But many who use them don't realise that they have dangerous side effects for wildlife.

Rat poisons are designed to work slowly in their target species, rats, so that they ingest lethal doses of the poisons. The rats then become sick and increasingly toxic over a period of days or weeks. Poisoned rats then become easy, highly toxic prey for predators.

The side effects of exposure to these poison compounds are especially worrying for local wildlife in Cape Town, South Africa. The city is situated within a global biodiversity hotspot that includes the world-renowned Table Mountain National Park. Here, with thousands of plant species already threatened by habitat loss and modification, the poisoning of numerous predatory wildlife species that help retain ecosystem stability could disrupt the delicate ecological balance.

Using samples from seven species, scientists from the Institute for Communities and Wildlife in Africa at the University of Cape Town investigated just how frequently Table Mountain's wild predators are exposed to rat poisons through their prey.

We detected five different commercially available rat poisons in the livers of 81% of the predators we tested. Predators included common ones such as genets, Cape Eagle owls, and water mongooses, and rarer ones such as caracals, otters, and a honey badger. The detection of rat poison in otters is especially interesting because it suggests that poisons used on land can make their way into the city's streams, wetlands and estuaries.

Some wildlife species are already threatened by habitat loss, vehicle collisions, poaching, disease, and fire. Rat poisons make these populations even more vulnerable to local extinction. When many species are affected within a single ecosystem, the effects of the poison exposure can escalate to threaten the functioning of an entire ecosystem.

The finding of widespread toxic exposure to rat poison in Cape Town's wildlife echo those for predatory species elsewhere in Europe and North America, such as polecats, owls and raptors, coyotes, endangered kit foxes, fishers, and bobcats. For some of these species, anticoagulants are named as a leading cause of death and are even linked with at least one dramatic population decline in a species similar to caracals, the North American bobcat. Researchers fear a similar fate for wildlife near Cape Town.

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A study conducted in Cape Town found that 92% of caracals had rat poisons in their livers. (Provided by author)

Multiple species exposed to rat poisons

In vertebrates – animals that have a backbone or spinal column – the liver is the organ responsible for removing toxins from the blood. This is where we looked for evidence of rat poison exposure. One challenge was that testing the liver meant we could only sample animals that were already dead, limiting how many animals we could assess.

To better understand how Cape Town's local predators come into contact with poisoned rats, we explored the rich data set of the Urban Caracal Project, which included liver samples from 24 caracals.

Alarmingly, 92% of caracals had rat poisons in their livers. But the amount of poison in their livers varied. Caracals that frequented vineyards had the highest levels. This may be because vineyards allow caracals a safe space to hunt close to the urban edge – where rat poisons are widespread.

But rat poisons are also affecting caracals that have never even seen a rodent. Our analysis also revealed a caracal kitten as having very high levels of poisons. It appears that mothers may inadvertently poison their own young through contaminated milk.

A widespread problem

With greater economic opportunities in cities, rapid urbanisation is a reality. The challenges of managing waste and the animals it attracts, are rapidly mounting.

Using poisons is quick but dirty from a wildlife perspective: the ultimate price will be paid by those animals at the top of the peri-urban food chain, such as leopards and caracals.

Raising awareness about this is the first step. Ensuring the conservation of urban wildlife needs changes in the way that people understand their individual impact on local ecosystems.

As consumers, people need more eco-friendly alternatives to rat poison. Nevertheless, the simplest solution is well within everyone's reach: Improve the management of waste which attracts rats in the first place.

Households can make a choice about whether they use poisons in or around their homes. In other parts of the world, similar research findings have galvanised the public and spurred regulations on the use of these poisons.

We hope these research findings will stimulate a similar dialogue with home owners, businesses, and municipal authorities on how to reduce environmental contamination by rat poisons and other toxins in Cape Town and beyond.


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Re: Poison meant for city rats is killing wildlife in South Africa

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Well no poison is found in our house ..Nature sorts it all out ..but sad to say some idiots in our complex put down Rat Poison and others called in Needed to be banned pest control companies ..Result 4 x DEAD Spotted eagle Owls ...Why people like to buy houses in Leafy suburbs when in reality most of them should be on the 23rd floor in Hillbrow


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Re: Poison meant for city rats is killing wildlife in South Africa

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The report refers to Cape Eagle owls as common ...Not in Cape Town ..They obviously mean Spotted Eagle Owls ..Another discredited scientific report belching out false info


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Re: Poison meant for city rats is killing wildlife in South Africa

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Peter Betts wrote: Tue Jun 04, 2019 8:38 pm The report refers to Cape Eagle owls as common ...Not in Cape Town ..They obviously mean Spotted Eagle Owls ..Another discredited scientific report belching out false info
Scientifically the species of the owl does not make any basic difference to the result ;-)


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Re: Poison meant for city rats is killing wildlife in South Africa

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Lisbeth wrote: Tue Jun 04, 2019 8:55 pm
Peter Betts wrote: Tue Jun 04, 2019 8:38 pm The report refers to Cape Eagle owls as common ...Not in Cape Town ..They obviously mean Spotted Eagle Owls ..Another discredited scientific report belching out false info
Scientifically the species of the owl does not make any basic difference to the result ;-)
..Well they should have done a proper job and called them ostriches then ..Science is meant to be accurate ..not Nursery Rhymes in my book


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Re: Poison meant for city rats is killing wildlife in South Africa

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Cape Town’s caracals are ingesting harmful ‘forever chemicals’ through their diet

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Caracals feed mainly on native, wild species. (Photo: Jacque Smit)

By Gabriella Leighton and Jacqueline Bishop | 18 Jul 2022

Caracals hunting in Cape Town’s vineyards and on development fringes where prey is abundant are likely to be exposed to a cocktail of highly toxic anticoagulant rodenticides, as well as DDT and polychlorinated biphenyls.
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If you live near or have visited Cape Town’s urban edge — where urban and natural areas meet — you may have been lucky enough to spot a caracal. These adaptable, medium-sized wild cats with distinctive long tufted ears can be found in other parts of the African continent too, as well as the Middle East, central Asia and India.

Caracals are the largest remaining predator in Cape Town, the world’s most biologically diverse city. It is estimated that there are around 50-60 caracals left on the Cape Peninsula. Our previous research has shown that the city’s caracals feed mainly on native, wild species, such as guinea fowl and vlei rats. And they choose to hunt for their prey close to the urban edge — particularly in areas where there are vineyards and wetlands nearby.

But this choice comes with risks. It means they need to cross roads to reach fragmented habitat patches; car collisions are an obvious threat. A less obvious one is persistent organic pollutants, or “forever chemicals”.

These long-lasting, toxic chemicals are largely invisible, travelling through air and water, and ending up even in the most remote environments. They affect both human and wildlife health. Since the 1940s they have been used in pesticides, industry and construction. These activities release the chemicals into air, soil and water. There they remain intact for long periods of time and may become widespread through natural processes.

These pollutants tend to accumulate in the body tissues of animals — especially predators. Chemicals build up in predators through the prey they eat, a process called biomagnification. This means predators can act as sentinels or indicators for the presence, diversity and level of pollutants in the environment.

Until now, most research on these chemicals has taken place in Europe and North America, with little focus on the Global South. Our research in Cape Town aims to address this gap. We’re investigating how local wildlife may be affected by a particularly toxic class of pollutants, the organochlorines. This group of man-made chemicals contains carbon, chlorine and several other elements. Among them are polychlorinated biphenyls, a group of highly carcinogenic chemicals formerly used in many industrial and consumer products.

We have studied the diet, hunting behaviour and pollutant levels in Cape Town’s caracals. Our latest findings reveal extensive exposure to these chemicals across the city’s complex mosaic of habitats.

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A caracal in a suburban Cape Town garden. (Photo: Anya Adendorff)

Caracals as indicators of environmental health
Working with wildlife ecotoxicologist Rafael Mateo at Universidad Castilla in La Mancha, Spain, we looked at how the caracals were being exposed to pollutants.

Samples were collected from caracals captured in cage traps as part of our work to monitor their movements using GPS collars. Animals were sedated and blood samples were taken by a veterinarian. We also collected blood and fat samples from dead caracals picked up around Cape Town, mainly animals killed in collisions with cars.

We tested samples using gas chromatography-mass spectrometry, a method which can detect and quantify pollutant chemicals in tissue samples even at low concentrations.

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The potential pathways of exposure to persistent organic pollutants in Cape Town’s caracals and their prey. (Graphic: Gabriella Leighton)

A worrying trend emerged: caracals frequently hunt in areas where there is a higher risk of organochlorine exposure. Individuals that hunt closer to denser human populations, and in wetlands and vineyards, have higher levels of both the insecticide DDT (dichloro-diphenyl-trichloroethane) and polychlorinated biphenyls in their blood and fat tissues compared with those that hunt further away.

This link to vineyards is a trend we have picked up before when assessing exposure to another kind of pesticide, rat poisons. Caracals hunting in Cape Town’s vineyards, where prey is abundant, are also likely to be exposed to a cocktail of highly toxic anticoagulant rodenticides.

Caracals using areas with a higher density of electrical transformers had higher burdens of chemicals in the polychlorinated biphenyls group. This is likely due to polychlorinated biphenyls leaking from the coolant fluids used in electrical equipment. The chemicals were banned worldwide in the 1980s and South Africa is committed to phasing them out by 2025.

Together, our results suggest that many human-transformed landscapes can harm wildlife, through previous or ongoing use of “forever chemicals”.

What can be done
Although this study is the first of its kind for southern Africa, it adds to the growing body of evidence that predator indicator species can reveal exposure to pollutants across food webs in human-transformed areas.

The world’s cities represent a new type of ecosystem for wildlife. Many species have adapted to these landscapes. But in doing so, they are forced into contact with invisible risks, such as increased exposure to pollutants.

Where a habitat contains both risk and reward, it can be an “ecological trap”, accelerating local extinctions. Ecological traps are also a global issue requiring collective action.

To make cities around the world safer, cleaner places, the use of “forever chemicals” must be reduced in line with existing international agreements. Citizens can reduce their own pesticide use too, particularly the use of rat poison. Cleaning up urban wetlands and restoring them could go a long way to removing pollutants from the environment.

People should also take stock of existing chemical use. Safely disposing of obsolete chemicals and outdated or contaminated equipment is an essential step in reducing spillover into natural areas.

These efforts will ensure healthier cities — not only for wildlife but for people too. DM

First published by The Conversation.

Gabriella Leighton is a Post-Doctoral Fellow at Rhodes University and Jacqueline Bishop is a senior lecturer in Conservation Biology at the University of Cape Town.


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Re: Poison meant for city rats is killing wildlife in South Africa

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I am sure it is not difficult to get more organic poisons? -O-


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