Written by Andrew Smart, Head of Science and Research
Emma Gardner et al (2024). A family of process-based models to simulate landscape use by multiple taxa. Landscape Ecology, 39(5), 1-26.
Over seventy toad patrols, together with Jenny Tse-leon, Froglife Conservation & Science Manager and Ashlea Mawby, Toads on Roads co-ordinator, have helped researchers build a computer model that simulates toad populations. The paper presenting the model has just been published and can be found here: s10980-024-01866-4.pdf (springer.com).
The project, led by Dr Emma Gardner at the UK Centre for Ecology and Hydrology, UK Centre for Ecology & Hydrology (ceh.ac.uk), aimed to build models for a whole range of different species with different life histories, including birds, bats, common lizard and common toad. The models consider species’ habitat preferences for reproduction and foraging, as well as their expected annual survival rates and movement ranges. For a given landscape, the models predict the relative abundance of species and where those species are likely to be spending their time.
The aim is that the models can help people discuss and understand how species might be affected by land use changes.
The new models belong to a special class of models called ‘process-based models’. This is because the computer attempts to simulate the foraging and population processes of the species. A big advantage of these kinds of models is that they can incorporate different types of information – for instance, they can combine measurements of how far species travel, calculated from long-term scientific studies, with expert opinion on what habitats species like to use collected via questionnaires.
Some extra tweaks were made to the models to help them simulate reptiles and amphibians. In the reptile model, the computer calculates the ‘solar illumination’ of habitats to identify good basking places. For the common toad model, road mortality was included, since – as our Toad Patrols know all too well – this can be a big danger for amphibian populations.
The project team worked with conservation volunteers to check how well the model’s predictions matched up to real observations of species abundance and habitat use. Surrey Amphibian and Reptile Group shared their detailed common lizard monitoring data, enabling the team to show that the models correctly predicted more common lizards in places where the surveyors recorded more lizards in real life.
When it came to checking how good the toad model was, Froglife’s Toad Patrols came to the rescue. Over seventy Toad Patrols supported by Froglife’s ‘Toads on roads’ project filled out questionnaires reporting which habitats their toads appeared to migrate from. The project team were able to show that the model’s predictions for where the toads were expected to be foraging matched up to the habitat types the toad patrols observed their toads to be coming from.
We have already begun using the models to assess the likely impact of habitat restoration plans, as well as estimating the impact of developments. Going forward, we hope these models can help decision-makers better assess the biodiversity consequences of landscape changes at both local and national level.
An example of how the model predicts where toads would be spending their time when foraging around their breeding pond. This particular breeding population is assisted by Bagley Wood Toad Patrol.