Tracking Toads and Pond Histories: New Fieldwork on Heathlands in Surrey

This summer, Professor Helen Bennion, PhD student Ben Siggery and MSc student Cassandra Li carried out fieldwork on two heathland sites in Surrey.

The project, in partnership with the Amphibian and Reptile Conservation Trust and Surrey Wildlife Trust, focuses on the failed reintroductions of the Natterjack Toad, an iconic British species that has seen dramatic declines over recent decades.

Once widespread, the Natterjack is now critically endangered in the UK. Its decline has been linked to habitat degradation and water acidification, with successful breeding heavily dependent on pond chemistry. 

At pH levels below 5.5, spawn survival becomes unlikely. Several reintroduction efforts across southern England in the 1980s and 1990s failed to establish sustainable populations.

The research team is using palaeoecological techniques to understand what went wrong. 

Sediment cores collected this June at Frensham Common and Churt Common will be analysed for diatoms, macrofossils, charcoal, and chemical signals to reconstruct past pond environments. 

The aim is to compare conditions before local extinction, during previous reintroductions, and in the present day, providing practical data to guide future conservation.

“For me, obviously the fieldwork days themselves are always great fun and very memorable,” said Ben Siggery. “I enjoy getting the opportunity to work with stakeholders at the different conservation bodies and being able to genuinely provide something of value to them, as well as being able to learn from their knowledge and experiences.”

This work supports the goals of national conservation initiatives, including Natural England’s Heathland Connections project and the newly designated Wealden Heaths National Nature Reserve. 

The study sites lie within areas of strategic importance for biodiversity.

Although analysis is still underway, the fieldwork has already raised questions. For example, researchers expected to find deeper sediments based on the ponds’ known history. 

One core from Churt revealed unusually acidic water, reflected in its striking colour, both unexpected and potentially significant.

By working closely with conservation partners, the project shows how academic research can feed directly into land management decisions. 

It also highlights the value of palaeoecology in addressing contemporary ecological problems.

More information

• Visit Professor Helen Bennion’s UCL Profile
• See Ben Siggery’s University of Surrey Profile
• Read the paper in The Journal of Environmental Management