New Research Shows Alarming Decline in Small Mammals in the UK

• Novel research finds alarming declines of some mammal species in the UK.

• Five of seven species of small mammals assessed found to have declined in occupancy (areas where present) by an average of 1.2-2.8% each year between 1970 and 2016.

• Some species previously thought not to be at risk, including weasels, stoats, and several species of vole and shrew, now of high concern requiring immediate conservation action.

UK, 02.11.21: In the first study of its kind in the UK, researchers have demonstrated a worrying decline in small mammals in Britain. The species found to be the worst affected are the harvest mouse and weasel, which were found to be shrinking in occupancy (area of land where they are present) by an average of 2.8% and 4.2% each year, respectively. The scale of decline found for the weasel, which primarily feeds on voles and mice, is enough to justify it being classified as ‘Vulnerable to extinction’ under IUCN Regional Red List Criteria.

The paper, published in Biological Conservation and authored by a team of researchers from the Mammal Society, University of Sussex, and the UK Centre for Ecology & Hydrology, assesses trends of two thirds of the UK’s land mammals from 1970 to 2016. The results are based on estimating each species  “occupancy”, which refers to the proportion of sampled areas in which a species is recorded as present.

Dr Frazer Coomber, Science Officer at the Mammal Society said: “By grouping mammal species into survey assemblages and creating detection histories from species presence records, occupancy-detection models were used to calculate the probability that a particular site was occupied and the species observed given that it was present. The proportion of all sampled sites that were estimated to be occupied could then be summed to get annual occupancy estimates.". 

One quarter of native British mammals were found to be at risk of extinction in the 2020 Red List for Britain’s Mammals, however this new study shows even further loss. While some species groups appear to be increasing (e.g. bats and deer) these new analyses highlight for the first time the declines in bank voles, field voles, water shrews, common shrews, stoats and weasels. All of these species were historically abundant, being found particularly in hedgerows, scrub and long grass.

Fiona Mathews, Professor of Environmental Biology at the University of Sussex, said:

“Small mammals are critical, and usually abundant, parts of natural ecosystems. They are tiny ecosystem engineers that improve the water holding capacity of our landscapes, and are vital prey for many other species including barn owls, kestrels, stoats and weasels. The disappearance of the long grass and overgrown areas they need has taken its toll.”

The study was undertaken to reveal previously unknown species trends, which are vital to provide suitable conservation management – something that is of paramount importance to retain biodiversity.

Dr Stephanie Wray, Chair of the Mammal Society, said: “This is the ‘canary in the coal mine’ that tells us we need to act now to stop ecosystem collapse”.

 

- Ends -

For further information, please contact:

• Mammal Society Press Officer, Sophie Webb: 02380 010983 pr@themammalsociety.org
• University of Sussex Press Officer, Stephanie Allen, 01273 873659 l.allen@sussex.ac.uk
• Centre for Ecology & Hydrology UK Press Office, Simon Williams, 07920 295384

Notes to editors

• Interviews/ photographs available upon request.
• The full paper “Using biological records to infer long-term occupancy trends of mammals in the UK, Coomber et al., 2021)”, published in Biological Conservation, and associated figures can be found online at:
  https://www.sciencedirect.com/science/article/pii/S0006320721004146
• The Mammal Society app to visually see the data can be found online at - https://mammalsociety.shinyapps.io/OccupanyTrends/

About the Mammal Society

One in four of our native mammals is threatened with extinction, and many others are in decline. With Britain now recognised as one of the most nature-depleted countries in the world, urgent action is needed. The Mammal Society is working to give our wildlife a better future by:

1. Keeping a constant watch on the conservation status of our mammals and making this information freely available
2. Making conservation more effective by providing guidance on what to do and where to do it
3. Educating the public and professionals about wild mammals, training people to survey them, and sharing the latest research
4. Working in partnership to restore native mammal populations and re-establish functional ecosystems

The Mammal Society is the only charity with an interest in all British mammals.

The Mammal Society’s conservation work is supported through the generosity of our supporters. A list of our current and past projects can be found here - https://www.mammal.org.uk/science-research/surveys/ To join the Mammal Society visit www.mammal.org.uk.

Recent Mammal Society publications include The State of Mammals in Wales and the Atlas of the Mammals of Great Britain and Northern Ireland. 

Visit www.mammal.org.uk for more information or follow the Mammal Society on Facebook @MammalSociety

About the University of Sussex

The University of Sussex has challenged convention since its foundation in 1961. From the campus’ modernist architecture on the edge of a rural national park, to our progressive academics and creative professional services staff, to the inspiring students who choose to learn and live here, to the very tone of the institution and the nature of its conversations, through to the expressions of radicalism, critical thinking and, at times, dissent.

Our research creates new agendas, contributes new knowledge and provides new ideas and solutions that are helping to shape the world. We challenge conventional thinking and discourses, offering inspiring and creative ways to understand and solve global issues.

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The UK Centre for Ecology & Hydrology is a centre for excellence in environmental science across water, land and air. Our 500 scientists work to understand the environment, how it sustains life and the human impact on it – so that together, people and nature can prosper. We have a long history of investigating, monitoring and modelling environmental change, and our science makes a positive difference in the world. The UK Centre for Ecology & Hydrology is a strategic delivery partner for the Natural Environment Research Council, part of UK Research and Innovation.

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