Froglife

Leaping forward for reptiles and amphibians

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What is a wetland?

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Written by Eve Goddard, Transforming Lives Trainee

A wetland is an area of land that is either permanently or seasonally covered by water. They are areas where water and land meet, can be as small as a puddle or as large as an ocean and can be natural or man-made. They form when water can’t drain away from an area. 

They include marshes, fens, bogs, wet grasslands, wet woodlands, rivers and ponds. 

Wetlands, when healthy, are one of the most biodiversity-rich environments in the UK and home to many species of bird, invertebrate, mammal, reptile and amphibian.

The juxtaposition of land and the water is integral to the lives of these species, and so from a conservation point of view, both elements need protecting from human disturbance and destruction. The UK has lost nine-tenths of its wetlands in the past 100 years; much of it has been drained for construction or agricultural use. 

Wetlands are also vital for humans, they play a key role in limiting the amount of carbon in our atmosphere and research is beginning to show the impact of blue spaces on our mental health and wellbeing.

What can you do to support our wetlands?

By building a pond in your garden. No matter how small, you are creating an important addition, a stepping stone in a wider wildlife corridor. Water beetles will fly from pond to pond, mammals and birds will drink and hunt, tiny mosquito larvae will eventually take flight and provide food for bats. If you are lucky enough amphibians will breed!

You can find guides on building different types of ponds here. 

Ponds in winter

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Written by Paul Arestides, Transforming Lives Trainee

At this time of year, especially January and February, our weather can turn cold with ice, frost and snow. It’s a good idea to keep an eye on our garden wildlife ponds and implement these handy tips below when needed. 

Amphibians like frogs, toads and newts tend to brumate on land during the colder weather, so its always a good idea to have spaces of the garden left untouched. Compost heaps, log piles or rocky places are good for them to settle down and help protect them from frost.

If you have a pond, or plan to build one, make it deep enough so it will not freeze completely (at least 60cm for amphibians) frogs may overwinter in the deeper areas, so this will give them the best chance to survive. Invertebrates like beetles, water boatmen and dragonfly larvae will dive to the bottom of the pond and stay dormant in deeper water.

Contrary to popular belief, melting a hole in the ice will not help the amount of oxygen diffusing into the water- although it can help amphibians like newts that need a hole to come up to the surface to breathe. Oxygen can be produced simply by having oxygenating plants growing in the pond.  If there is heavy snow, remove this from the surface ice with a brush to allow sunlight into the water- allowing the plants to continue photosynthesising and creating oxygen.

Do not break the ice as this can send out shock waves that can kill overwintering creatures. Tipping warm/boiling water into your pond isn’t a good idea either as this can trigger animals to come out of their brumation state earlier than planned. 

For further tips, take a look at our Winter Wild Gardening Campaign page. 

 

 

Climbing salamanders: perspectives from great heights

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Written by Laurence Jarvis (external contributor)

Climbing salamanders within the genus Aneides are a fascinating group with varied behaviour and ecology. There are currently 10 recognised species, found predominantly across North America and Canada, notably California and British Columbia. The genus belongs to the Plethodontidae, which is the largest salamander family, comprising approximately 518 species. Most plethodontid salamanders are endemic to North America and, unlike many European salamanders, lack lungs and instead completely rely on gaseous exchange through their skin. They have evolved to live in a large range of habitats including streams, trees, on land and underground. Most are direct developers, laying eggs on land which hatch into live juveniles which resemble miniature adults.

The arboreal salamander (Aneides lugubris) is the largest of the genus, growing up to 100 mm with a rounded, robust body. As its name suggests, it is excellent at climbing and may ascend trees up to 18 metres, using specially adapted toes with expanded tips1. Uniquely amongst salamanders, the tail is prehensile enabling it to cling to the branches of trees. Arboreal salamanders are highly aggressive, possessing rows of sharp teeth. Both males and females have been reported with scars on their bodies as a result of aggressive combat1. Despite these tendencies, arboreal salamanders perform parental care and either the male or female will guard their clutch of around 5-26 eggs whilst they develop. Like other members of the genus, the eggs are laid in damp areas of rotting wood such as under tree bark. After hatching the small juveniles remain with their parents in family groups. 

Figure 1. The Arboreal salamander (Aneides lugubris) is a highly mobile species living within Californian forests.

Wandering salamanders (A. vagrans) are as equally mobile and arboreal as A. lugubris and will climb trees very readily. They have been reported to ascent up to 87 metres in Douglas fir forests of British Colombia2. If disturbed individuals exhibit an unusual behaviour of jumping from the tree canopy and performing an aerial skydive to land safely. Unlike other species which may jump and glide from a height, such as flying squirrels or frogs, wandering salamanders do not possess obvious adaptations such as flaps of skin to slow their fall. Therefore, this behaviour seems unexpected. Recent research by Brown et al. (2022)3 examined the morphology and aerodynamics of individuals as they fell under experimental conditions in a wind tunnel. They found that, compared to other species within the genus, wandering salamanders have more flattened bodies and slightly wider toes, which they spread during their fall. In addition, individuals stretch out their limbs in a skydive posture and undulate their bodies. The researchers showed that these combined behaviours slowed their fall and prevented damage on impact with the ground.

Climbing salamanders are unusual amongst amphibians since the adults of several species are monomorphic, that is, both males and females are of equal size. The vast majority of amphibians (over 90%) show a degree of sexual dimorphism, with females often being larger than males. However, in plethodontid salamanders, males are often larger than females. It is thought this is because they are highly territorial and use their size to defend territories. Many other frog and toad species possess other dimorphic traits which may include differences in skin colour or development of secondary sex characters such as nuptial pads. The Sacramento Mountains Salamander (A. hardii) is one of the Aneides salamanders that is sexually dimorphic with males being larger and possessing wider heads than females. Other members of the Aneides genus are monomorphic, with females also having large bodies and wider heads like males.

Since many other plethodontid salamanders are sexually dimorphic it is thought that increased male size over females is the ancestral state4. Research by Staub (2021)4 examining the evolution of plethodontid salamanders suggests that the monomorphism observed in species of the Aneides genus has evolved later. These monomorphic species are therefore described as having ‘derived monomorphism’, since they have evolved from sexually dimorphic ancestors4. The exact reason for the similar size in both males and females is uncertain but Staub et al. (2024)5 postulated that higher levels of androgen hormone in females may explain their equal size to males. However, their experimental work did not confirm this. Therefore, further research is required to determine whether there are differences in steroid sensitivity or signalling within females, rather than different levels of hormone5.

Figure 2. The wandering salamander (Aneides vagrans) may jump from treetops and perform a skydive to land safely.

Climbing salamanders are a unique group and whilst several species are common and widespread, six species within the genus are listed as either Near Threatened or Vulnerable. Habitat loss is a continual problem with unsustainable logging causing the declines in several species. The Shasta Black Salamander (A. iecanus) is now classed as Vulnerable, and has suffered rapid declines due to the construction of the Shasta Reservoir in California. Like other plethodontids, climbing salamanders are also vulnerable to climate change and several species have suffered due to longer and drier summers across their range. Conserving these threatened species is a challenge and combined conservation efforts are required to protect these fascinating species.

Click for References

1AmphibiaWeb (2024). <https://amphibiaweb.org> Aneides lugubris. University of California, Berkeley, CA, USA. Accessed 12 Dec 2024.

2AmphibiaWeb (2024). <https://amphibiaweb.org> Aneides vagrans. University of California, Berkeley, CA, USA. Accessed 12 Dec 2024.

3Brown C.E., Sathe E.A., Dudley R. and Deban S.M. (2022). Gliding and parachuting by arboreal salamanders. Current Biology, 32 (10): R453-R454.

4Staub N.L. (2021). The evolution of derived monomorphism from sexual dimorphism: a case study on salamanders. Integrative Organismal Biology, 3 (1): p.obaa044.

5Staub N.L., Hayes S.G. and Mendonca M.T. (2024). Levels of Sex Steroids in Plethodontid Salamanders: A Comparative Study Within the Genus Aneides. Ecology and Evolution, 14 (11): p.e70550.

What our animals are doing this month

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Written by Paul Arestides, Transforming Lives Trainee

Happy New Year to you all. It’s January and the start of 2025, our weather doesn’t seem to be getting any more predictable and the warmer winters do have an impact on our amphibians and reptiles. These animals usually rest up over winter, either in the bottom of ponds, in rocky crevices or finding places underground to brumate, hidden away from cold or freezing conditions.

As the climate warms, however, we are noticing changes in behaviour. Our winters in the UK are now generally milder and can tempt amphibians and reptiles out of their brumation state. With reports of newts and frogs in ponds in January, even in full breeding condition, is now fairly normal in southern counties. Snakes and lizards will also make an appearance when the winter sun is strong enough, and all this would have been unheard of 15 or 20 years ago.

All the evidence is now pointing to our reptiles and amphibians emerging from their slowing-down period and breeding earlier than ever before, in response to our ever-changing climate.

It is still too early to predict the implications of these changes in behaviour, but a consequence of this has been on our reserve at Hampton with delayed pond maintenance due to the higher risk of harming our pond animals as they stay active for longer. This year we will be starting our great crested newt surveys earlier in response to breeding patterns.

With an unpredictable climate it can cause issues if newts, frogs or toads breed earlier with higher risks of frozen ponds,  spawn and eggs. Being more active over winter could also have negative impacts on our species life expectancy- using up energy reserves when they would normally be brumating. Food sources will be scarce over the winter months, so feeding becomes harder.

You can help us in our research by uploading your sightings of frogspawn or any amphibians and reptiles on our free Dragon Finder App – these records help us learn more about how our changing climate affects our species.

 

Heaths – an ancient and unique habitat

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Written by Charles Bonnett, Transforming Lives Trainee

 

What Is Heathland?

Heathland is one of our most distinctive and valuable ecosystems. Found mainly in areas with nutrient-poor, sandy soils, heathlands are most commonly associated with upland and lowland regions, creating a mosaic of habitats vital for biodiversity.  Historically, heathlands developed through human activity stemming back to the Neolithic period, particularly as a result of deforestation and grazing, which established and maintained their open, shrubby character.

In the UK, heathlands are divided into two main types: lowland and upland heath. Lowland heath occurs at altitudes below 300 meters and is primarily found in southern and eastern England, including Dorset, Surrey, and Hampshire. Upland heath, on the other hand, is found in Scotland, northern England, and Wales, often merging with moorland.

 

Ecology

Heathlands are home to a wide array of flora and fauna, many of which are rare or threatened. For example, they provide essential habitats for ground-nesting birds like the nightjar and the Dartford warbler. And, of course, our reptiles such as the sand lizard and smooth snake rely on this habitat, benefiting from the warm, open conditions. The vegetation of heathland is often characterised by low-growing shrubs such as heather, gorse, and other acid-tolerant plants.

Threats and Conservation

Despite their ecological significance, heathlands are among the most threatened habitats in the UK, with only 20% of the historic lowland heathland area remaining. Urbanisation, agricultural intensification, afforestation, and abandonment of traditional management practices have contributed to their decline.

However, fantastic conservation efforts continue, employing techniques such as controlled burning, grazing, and turf stripping to maintain the open character of heathlands and prevent succession to woodland.

Recreational Value

As well as their ecological importance, heaths hold beneficial recreational value. Often positioned close to urban areas, heathlands are popular destinations for walking, birdwatching, and other outdoor activities, connecting people with nature.

Overall, heathlands are a crucial component of the UK landscape, with significant historical, ecological, and recreational value, and so the ongoing conservation work to maintain these habitats will continue to be of significant importance, now and into the future.

Find out more about how we are working to restore heathlands for our species here.