Are Britain’s wild mammals consuming plastic?

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Logo: The Mammal Society
Wood mouse (Gary Cox)
Wood mouse (Gary Cox)

This project has now been published and you can read the full press release here (2022)

As you will have seen on programmes such as the BBC’s Blue Planet, plastic in our seas threatens marine ecosystems. However, to date, very little is known about the impacts on terrestrial species. A team from the Mammal Society are setting out to assess the exposure of wild mammals to waste plastics across the UK. By analysing the droppings of some of our most widespread species — squirrels, rabbits, mice, voles, rats, shrews and hedgehogs — they will find out the extent to which these plastics are eaten. The team will also assess the health threats posed by different types of plastic, through both ingestion and entanglement.

Waitrose & Partners’ Sustainability Team, who have helped to fund the research as part of their Golden Jubilee Trust award scheme, told us that they were interested in finding out more about the effects of plastic on the environment. The Partnership set up the Golden Jubilee Trust (GJT) in April 2000 to mark the 50th anniversary of the co-ownership business structure. Itself a registered charity, the GJT offers secondments for their staff which enable UK registered charities to achieve their goals. Emily Dempster, who works at Waitrose & Partners in Hove and is also a 3rd year Zoology student at the University of Sussex, has been awarded a secondment to work with the Mammal Society on this project. The findings will be used by the company’s sustainability team to help improve their environmental impact.

Emily Dempster
Emily Dempster

We talked to Emily (pictured) who is working on this project about the reasons behind the study and what she will be doing.

What prompted the Mammal Society to begin this study?

In the UK food packaging accounts for 67% of plastic waste, which is far higher than that of many other EU countries. This suggests that UK supermarkets use more plastic in their packaging than in most of their other EU counterparts. Reports suggest that contamination by microplastic (1) in terrestrial habitats may be as much as 30 fold larger than on marine habitats. Studies conducted so far on terrestrial ecosystems have mostly focused on worms, soils and chickens. The research suggests that microplastics are present in high quantities across the board. This has led to many researchers calling for more research to be done on terrestrial ecosystems.


How could microplastics get into terrestrial ecosystems?

Microplastics find their way into the soil via sewage sludge, plastic mulching and landfill sites. As there is such a vast quantity of supermarket plastic packaging ending up in landfill and littered on UK roads this also means that there is a high chance of our wildlife coming into contact with it at some point in their lifetime. Through a combination of time, exposure to UV light and the high likelihood of different species of wildlife chewing large pieces of plastic they often break down into microplastics. This allows for microplastics to enter both the soil to be ingested in species such as worms and it is thought that animals that chew litter will also be ingesting microplastics. Both of these situations lead to microplastics entering the terrestrial food web. Through studies in marine ecosystems we now understand that there is cumulative effect when smaller organisms that have ingested microplastic are eaten by their predators. Through existing studies looking at worms and snails, it is understood that even small quantities of microplastics can stop normal growth and reduce the chance of successful breeding in individuals. So, this could result in species that are already facing many threats to their survival being at more risk.

Pygmy shrew (John Phillips)
Pygmy shrew (John Phillips)

Why small mammals?

One in five of Britain’s mammals is facing extinction and the conservation status of many other species remains unknown. It is therefore important to identify, and address, possible threats. For example, it is not currently known whether hedgehogs are ingesting microplastics via the invertebrates they eat. As small mammals are some of the most likely species to chew litter it is thought that they could be assisting microplastics to enter soils, waterways and food webs in terrestrial ecosystems. Small mammals are very important for indicating the health of ecosystems as they are vital prey for a wide variety of species such as foxes, weasels, barn owls and kestrels. If small mammals are ingesting microplastics this would have an important impact on the health of these other species. By studying mice, rats, shrews, rabbits, hedgehogs, squirrels and voles we hope to better understand the current situation and raise awareness of the effects of microplastics on our terrestrial UK wildlife.

How can people get involved?

There are numerous ways to get involved — if you are part of a university or wildlife group you can take part in humane mammal trapping in order to gain samples of droppings. Wildlife rescue centres can take part by sending us samples of newly arrived patients, and if you are a member of the public with small mammals in their garden, shed or house, you can collect droppings and send them to us. If you are interested but cannot send samples then you can send us any photos of any wild mammal entangled in plastic or teeth marks in plastic waste you see around where you live. Finally, you can donate to our appeal for the equipment we vitally need in for the laboratory analyses.

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For more information about the Mammal Society visit our website at You’ll find details about specific volunteering positions and permanent roles here, as well as advertised on social media and on the CJS site.


1 Microplastics are defined as anything under 5mm but we are likely to find them ranging from 1mm to several micrometres.

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Posted On: 06/03/2020

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