Frogs and toads need a Scottish Environment Act

Common toad emerging from terrestrial habitat at a site in southern Scotland. © Froglife

This blog is by Froglife, and was first published on the Froglife website.

Scotland supports six species of native amphibian and four native reptile species. These charismatic species form a valuable part of Scotland’s biodiversity and form an important role in effective ecosystem functioning. Most are secretive and often go unnoticed, but are appreciated in the many and diverse habitats where they occur.

Common frogs and common toads are perhaps the most well recorded species, being obvious in parks and gardens during spring breeding and migration. Both species have a widespread distribution along with smooth newts and palmate newts which are more secretive. Great crested newts have a more scattered distribution in Scotland while the nattterjack toad is confined to a small number of isolated saltmarshes along the Solway coast. In addition one introduced species, the alpine newt, occurs at a few sites across central Scotland. The three established native reptiles in Scotland include the adder (or northern viper), slow-worm and common lizard. Adders may be seen basking in warm sunshine in March and slow-worms often frequent garden or allotment compost heaps. In addition, the grass snake has recently been reported as occurring in the southern belt, particularly around Dumfries and Galloway (McInerny & Minting, 2016). Around the inshore waters a number of turtle species have been recorded including the leatherback turtle, loggerhead turtle and Kemp’s ridley sea turtle.

In recent decades populations of our most common amphibian and reptile species are under threat from a number of anthropogenic factors including habitat loss and fragmentation, introduced diseases, pollution and climate change (Downie et al., in press). The Fight for Scotland’s Nature campaign (www.fightforscotlandsnature.scot) aims to raise awareness of the plight of Scotland’s valuable species and protect and enhance Scotland’s natural environment. If you would like to help, please sign the petition/respond to the consultation at www.fightforscotlandsnature.scot/action/.

One of the biggest factors contributing to declines in Scotland’s native amphibian and reptile populations is habitat loss. For amphibians pond loss, coupled with a reduction in terrestrial habitat, has resulted in declines in many species. Research carried out by Froglife in 2016 showed that across the UK, common toad populations have declined by 68% over the past 30 years (Petrovan & Schmidt, 2016). In addition, filling in of garden ponds is likely to have negatively impacted common frog populations, which thrive in urban habitats and rely on garden features such as ponds for their successful breeding.

Habitat fragmentation is also a big problem, especially for migratory species with habitual breeding ponds such as common toads and great crested newts. Collisions of amphibians on roads can lead to massive mortality and is one of the factors thought to be responsible for the long-term decline in UK and continental European toad populations (Petrovan & Schmidt, 2016). Introduced diseases including Ranavirus have had negative impacts on common frog populations. Also, a rise in the pet trade and an increase in members of the public housing exotic pets, has increased the risk that emerging infectious diseases like Batrachochytrium salamandrivorans (Bsal) will become introduced into wild newt populations (Cunningham et al., 2019).

In an attempt to combat these threats, the national charity Froglife are carrying out a number of conservation programmes to help a range of amphibian and reptile species. The Come Forth for Wildlife project is in its development phase, thanks to funding from the National Lottery Heritage Fund. If the main project is funded, this will tackle habitat loss in the Forth region of southern Scotland.

Through targeted restoration and creation of amphibian and reptile habitats, along with public education programmes, we will help preserve vital habitats for these species in this highly populated region of Scotland. Once habitats have been created and restored, Froglife are committed to re-visiting each site 1, 3, 5 and 10 years post-completion to ensure that they remain viable and successful for maintaining amphibian and reptile populations.

Road mitigation schemes are increasingly using under-road tunnels or culverts to help direct movements of amphibians from terrestrial to breeding habitats and prevent the negative effects of habitat fragmentation. Little research has demonstrated the success of tunnels in providing suitable corridors for amphibians. Research by Froglife in England has suggested that in certain circumstances tunnels may be effective in mitigating the impacts of road construction by linking key habitats, especially for the protected great crested newt (Jarvis et al., 2019). However, no research has demonstrated the success of tunnels for great crested newts in Scotland, where this species may have different habitat requirements (Harper et al., 2019). Froglife is carrying out a study on six newly created amphibian mitigation road tunnels at a site in southern Scotland with nationally significant populations of great crested newts. The research will determine whether the implementation of tunnels at this site is successful and will be important for determining the success of future tunnel mitigation projects.

Amphibians and reptiles face an uncertain future in Scotland but you can help by supporting The Fight for Scotland’s Nature campaign (www.fightforscotlandsnature.scot). This will help us to work together to protect the valuable amphibian and reptile species of Scotland, enable us to set clear ambitions for Scotland’s environmental policy, conserve habitats and create a more sustainable future.