Climate change is already threatening wildlife in Berks, Bucks and Oxon

Climate change is already threatening wildlife in Berks, Bucks and Oxon

A blue tit with a caterpillar. Picture: Gillian Lloyd

Plants and animals across Berkshire, Buckinghamshire and Oxfordshire are already being seriously impacted by our changing climate, BBOWT research has warned.

Numbers of dormice recorded at nature reserves in all three counties have decreased since 2010 in a change linked to warmer winters; hotter summers could see beech trees disappear from some local areas, and there is strong evidence that caterpillars are emerging at different times of year, impacting breeding birds.

The Berks, Bucks and Oxon Wildlife Trust (BBOWT), which manages more than 80 nature reserves across the three counties, has highlighted some of these troubling cases in its latest 10-year action plan to mitigate the effects of climate change at the sites it manages. It comes as the UK prepares to host the COP26 UN climate conference in Glasgow next month.

Wildmoor in storm by Roger Stace

Wildmoor in storm by Roger Stace

BBOWT’s Head of Ecology Debbie Lewis, who led the research, said:

“We all know that climate change is happening around the world and is likely to get worse in many places, but now we are starting to see it threatening plants and animals in our local area, which is deeply worrying. We are seeing compelling evidence that warmer winters are already disrupting animals’ phenology – the way their life cycles are linked to seasonal weather patterns.

“We can also predict that, if our climate continues to change in the ways that have been predicted, some of our much-loved native species will struggle to survive. BBOWT can’t stop climate change, but by building a picture of its effect on wildlife we can work out which species and habitats might be most at risk and then take steps to protect them.”

Local case studies

BBOWT is in a particularly good position to look at the effects of climate change locally: since 2002 it has been carrying out a detailed monitoring program of species and habitats across its nature reserves. This means it has already been able to record changes in species populations which may be linked to changing climate. It’s a mixed picture, and some species are losing out to climate change, but there are some winners too.

The research also identifies the habitats at BBOWT reserves which are most at risk from climate change - all of them aquatic: lowland fens, 'eutrophic standing waters' and rivers.


Climate change losers

Flooding at BBOWT's Chimney Meadows nature reserve in West Oxfordshire. Picture: Louise King

Flooding at BBOWT's Chimney Meadows nature reserve in West Oxfordshire. Picture: Louise King

2007 Floods: One of the most dramatic climatic events the Trust has recorded the effect of is the now-famous 2007 floods, the worst in the Thames Valley since 1964. At BBOWT's Chimney Meadows nature reserve in West Oxfordshire, the population of unwanted flood-tolerant species such as grasses and sedges rocketed after the floods, while populations of wildflowers such as common knapweed and meadow vetchling all plummeted.

Although it is impossible to link those floods directly to wider climate change, the Intergovernmental Panel on Climate Change (IPCC) has predicted that extreme weather events such as this are likely to increase.

A dormouse running up a tree branch. Picture: Terry Whittaker/2020Vision

A dormouse running up a tree branch. Picture: Terry Whittaker/2020Vision

Dormice: BBOWT regularly counts the numbers of dormice at nest boxes at three nature reserves - Chinnor in Oxfordshire, Bowdown Woods in Berkshire and Little Linford Wood in Buckinghamshire.

The research shows how the average dormouse count at each site steadily decreased from 2010 to 2018. This ties in with national surveying which estimates that the species' range in the UK has shrunk by around half in the last 100 years.

Although it is not possible to say exactly why populations are decreasing, hibernating animals such as dormice often use weather cues to trigger emergence from hibernation, and it is thought that, because of increasingly warm winters, dormice are waking up sooner than normal when there is not enough food around for them to eat.

Beech trees in an autumn woodland. Picture: Andy Bartlett

Beech trees in an autumn woodland. Picture: Andy Bartlett

Beech trees: Beech woodland is common across southern England and Wales, particularly in the Chilterns and the Cotswolds. However, these trees are particularly sensitive to drought, and are likely to be especially vulnerable to the changes in rainfall and temperature that are projected for the south-east of England in the coming years.

Natural England's Climate Change Adaptation Manual warns that, on some less-suitable soils on southern-facing slopes, beech is likely to decline or disappear entirely.

A blue tit with a caterpillar. Picture: Gillian Lloyd

A blue tit with a caterpillar. Picture: Gillian Lloyd

Birds and caterpillars: Many birds, including blue tits, great tits and pied flycatchers, feed their chicks largely or entirely on caterpillars, and so hatch their young at the time of year when there should be the biggest number available.

However, the research warns that numerous studies in recent years have shown that warmer winters and springs in the UK are prompting trees and shrubs to come into leaf earlier, which is prompting caterpillar numbers to peak earlier.


Climate change winners

Dartford warbler

Dartford Warbler perched on gorse by Richard Steel/2020VISION

Dartford Warbler: Not all of the impacts of climate change are detrimental to species survival, and the Dartford warbler is a good example of this. Traditionally thought of as a Mediterranean species, this small songbird is also found across southern Britain, including at BBOWT's Wildmoor Heath reserve in Berkshire.

The research shows how warbler numbers recorded at Wildmoor took a nose dive after a series of particularly cold winters around 2010, but have since recovered well. This suggests that the warbler could be one of the local climate change 'winners' if the UK continues to warm up.

A willow emerald damselfly at BBOWT's Hosehill Lake reserve. Picture: Derek McEwan

A willow emerald damselfly at BBOWT's Hosehill Lake reserve. Picture: Derek McEwan

New species: The Trust has also recorded a number of new species at its nature reserves in recent years, the arrival of which has been linked to a warming climate. Until very recently, the willow emerald damselfly's breeding range was restricted to continental Europe, but in the past few years it has been recorded at two reserves in Buckinghamshire. 

Other ‘new’ species, or those expanding their distribution within the UK, include hobby, cattle egret, little egret and little bittern. These species are predicted to shift northwards as continental Europe becomes warmer and its wetlands suffer from drought.

What next?

Despite all of the potential risks, the research concludes that BBOWT's nature reserves are 'likely to remain good for wildlife in the face of climate change', because they are managed for wildlife and conservation.

Debbie Lewis added: "The suite of species (both flora and fauna) present on reserves in the future is highly likely to be different to that found today.  The reserves will remain good for wildlife – but it may be different wildlife.

“We know that we can’t fix climate change without restoring nature – nature has many of the solutions. We need more nature everywhere and BBOWT is working hard to achieve that in our three counties for nature, people and climate.”

The research concludes with a list of recommended next steps, beginning with continued monitoring and assessment of nature reserves. It goes on to outline some of the potential management techniques which could be used to help species at risk, such as creating more habitat or relocating animals and plants to better sites. Nature-based solutions, such as restoring floodplain meadows or woodlands to help capture carbon, are central to tackling climate change.

To find out how you can help tackle climate change by making small changes in your own life visit

Editor's notes

The report begins by pointing out the evidence for changes in the British climate, for example the fact that the top 10 warmest years since 1884 have all occurred since 2002, and the highest summer temperature ever recorded in the UK was in 2019 (38.7 °C). It also highlights nationwide changes in the natural world which have been linked to climate change, such as the fact that great tits in the UK now lay their eggs on average 11 days earlier than they did in 1968.

Natural England Climate Change Adaptation Manual :


Birds, caterpillars and climate change: One study, led by Researchers from the Norwegian University of Science and Technology, working with the University of Oxford, found that, while birds can adapt to warmer winters and springs by breeding earlier, they are not adapting fast enough. The British Trust for Ornithology, in its annual Garden Birdwatch Survey last year, said it recorded a five per cent drop in the number of blue tits recorded across the country – which would equate to roughly 500,000 birds if accurate. This recording coincided with a particularly warm or early spring, which would tie in with predictions about how climate change is likely to affect many insectivorous bird species.