Written collaboratively by participants on our Wild Memories project in Somerset
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Climbing salamanders: perspectives from great heights
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.
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.
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.
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.Click for References
1AmphibiaWeb (2024). <https://amphibiaweb.org> Aneides lugubris. University of California, Berkeley, CA, USA. Accessed 12 Dec 2024.
What our animals are doing this month
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
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.
Great crested newt activity while overwintering in ponds – Information request
Written by Andrew Smart, Head of Science and Research
Froglife are interested in gathering information about great crested newts overwintering and remaining active in ponds in the UK during the months of November to February. We would appreciate anyone who has any winter records of great crested newts active in their garden ponds or local ponds contacting us by email on: winterGCN@froglife.org (see below for details).
Following a recent article on overwintering and neoteny, Froglife has been made aware of a garden pond where great crested newts continue to show activity while overwintering in the pond. While small numbers of newts have been known to overwinter, its not something that has ever been widely recorded.
Griffiths et al (2010) found that milder wet winters are linked to low survival rates in great crested newts, with overwintering animals away from the pond being unable to feed but continuing to deplete energy reserves. Investigations of the metabolic rates of overwintering alpine newt (Kristín and Gvoždík, 2014) found that individual metabolic rate was related to body mass loss, which in turn is linked to reproductive success, immune response and future survival. Griffiths et al found the implications of any potential change in climatic conditions on a regional scale could result in the loss of metapopulations while variation in survival of individual populations may be linked to changes in summer climate.
With milder winters in the UK it may be that some newts that previously adopted a higher-risk strategy (exposure to winterkill) of overwintering in ponds may find themselves able to feed and be in better condition at the start of the breeding season. Triturus carnifex (Mori et al 2017) have been found to remain present in ponds in Italy throughout the year with low numbers recorded in December, January and February. In Norway (Dervo et al 2018) great crested newts have been found to migrate as much as 1300m to find suitable hibernation sites to escape the cold; searching for hibernacula is another energy cost, dehydration and predation risk that could make partial migration a strategy that could be beneficial in warmer winters.
Partial migration is known in other newt species including the red spotted newt (Notophalmus viridens) in the USA, where a study (Grayson et al, 2011) found that animals were able to switch overwintering strategy and that density influenced the probability of remaining in a pond overwinter. Variation in reproductive success over time resulted in the maintenance of both resident and migratory strategies.
Froglife would appreciate anyone who has any winter records of great crested newts active in their garden ponds or local ponds contacting us by email on: winterGCN@froglife.org with the following details:
- dates of activity
- one of: OS Grid reference / ‘what three words’ location code/ postcode (or address of garden pond)
- Approximate area of pond
- Approximate depth of pond
- Any information about numbers seen and activity
Please remember that great crested newts are protected from disturbance under the Wildlife and Countryside Act and a licence is needed to survey. Obviously, any animal overwintering is at risk if disturbed, so please, if you are licenced don’t undertake any extensive torchlight surveys that could disturb animals and deplete energy levels; at this stage all we are interested in is a set of records to determine the extent of activity and location.
Dervo, B.K., Museth, J. and Skurdal, J., 2018. Assessing the use of artificial hibernacula by the great crested newt (Triturus cristatus) and smooth newt (Lissotriton vulgaris) in cold climate in Southeast Norway. Diversity, 10(3), p.56. Grayson, K.L., Bailey, L.L. and Wilbur, H.M., 2011. Life history benefits of residency in a partially migrating pond‐breeding amphibian. Ecology, 92(6), pp.1236-1246. Griffiths, R.A., Sewell, D. and McCrea, R.S., 2010. Dynamics of a declining amphibian metapopulation: survival, dispersal and the impact of climate. Biological Conservation, 143(2), pp.485-491. Kristín, P. and Gvoždík, L., 2014. Individual variation in amphibian metabolic rates during overwintering: implications for a warming world. Journal of Zoology, 294(2), pp.99-103. Mori, E., Menchetti, M., Cantini, M., Bruni, G., Santini, G. and Bertolino, S., 2017. Twenty years’ monitoring of a population of Italian crested newts Triturus carnifex: strong site fidelity and shifting population structure in response to restoration. Ethology Ecology & Evolution, 29(5), pp.460-473.Click for references
Impact of basking banks on UK reptiles
A new study by The University of Reading and Froglife highlights the impact of constructing Basking Banks on four UK reptile species and the implications for reserve management.
Researchers studying reptiles as part of a long-term monitoring programme found that in the 12 months after constructing basking banks only viviparous lizards were observed near them. However, in subsequent years, barred grass snakes increased near the banks and slow worms were observed for the first time. In nearby areas (approx. 100m away) with no basking bank construction, European adder observations increased and barred grass snake observations decreased. The basking banks created in this study were north-south facing, maximising their potential for thermoregulation, and were also full of holes and crevices that may be attractive to reptiles for predator avoidance.
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In subsequent years of the basking banks being constructed, barred grass snakes increased near the banks and slow worms were observed for the first time.
“This is an interesting finding because it suggests the simple practical action of building basking banks can enhance local reptile diversity. We think reptiles probably used the banks even more extensively than was recorded, as they are good places to hide from researchers.” Dr Brian Pickles, University of Reading.
The study was conducted as a part of a long-term partnership between Froglife and The University of Reading and contributes towards Froglife’s commitment to testing one habitat management intervention per year. Froglife is an ambassador for The University of Cambridge’s “Conservation Evidence” project and this research will add to the available evidence on actions to support reptile conservation in the UK, which is currently very limited.
“It’s essential that we take action to protect reptiles in the UK; we hope that this study will inspire members of the public to get involved in reptile monitoring schemes, and also inspire site managers to set up similar surveys and manage habitats for the benefit of reptiles as well as other species.” Jenny Tse-Leon, Head of Conservation and Impact at Froglife.
The UK has six native reptile species, and all are legally protected by the Wildlife and Countryside Act (1981) and section 41 of the Natural Environment and Rural Communities Act (2006). Despite this, reptiles are the least recorded vertebrate taxon making population trends difficult to obtain for most reptile species, even the most common ones. Globally, the need for improved conservation action to tackle reptile declines is gaining wider recognition.
In Feb 2019 basking banks were created by Froglife with the goal of expanding the favourable habitat for the European adder and hopefully increasing their local population. Each bank replaced a patch of grass with a raised area of rock, brick, and bare earth with a roughly flat rectangular centre (approx. 1 x 2 m) and the longest sides facing north/south at a height of ~50 cm with ~45o downward slope. Coupled with a long-term reptile monitoring programme at the site, this enabled a 5-year before-after control-intervention study of the impact of basking bank creation on habitat use by four co-occurring UK reptile species: European adder (Vipera berus), barred grass snake (Natrix helvetica), slow worm (Anguis fragilis), and viviparous lizard (Zootoca vivipara).
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This small-scale study shows the utility and importance of performing reptile monitoring before as well as after management interventions.
Interestingly, while the intervention was targeted at European adders, the researchers found that adder numbers increased in the wider area rather than directly around the basking banks. The banks themselves became important for barred grass snakes on the site. This small-scale study shows the utility and importance of performing reptile monitoring before as well as after management interventions, and the authors suggest that similar studies would benefit from directly monitoring reptile use inside the basking banks where possible. Adding basking banks appears to be a low-cost intervention with benefits for local reptile populations that can be carried out with small teams of volunteers, so it could be a useful addition to charities and site managers operating with small budgets.
You can read the full paper here.