Archives for 2025

Ponds in winter

February 1, 2025 by Admin

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.

What is a wetland?

February 1, 2025 by Admin

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.

Year of the snake

February 1, 2025 by Admin

Written by Emma Byrne, Transforming Lives Trainee

2025 is the Year of the Snake according to the Chinese Zodiac. In light of this, let’s look at the three native snake species in the UK.

Adder – The UK’s Only Venomous Snake

The adder is the only venomous snake in the UK. This small, stocky species thrives in woodland, heathland, and moorland habitats. Females incubate their eggs and can give birth to as many as twenty live young! Adders hibernate starting in October and emerge in March to bask in the sun. Adders are easily recognized by their distinctive dark zig-zag pattern and red eyes. Males are more silvery-grey, while females are often lighter or reddish-brown. Although venomous, they are shy and prefer to avoid humans.

Grass Snake – Britain’s Longest Snake

Grass snakes can grow over a meter, making them the longest snake in the UK. They are typically grey or green and feature a yellow and black collar around their neck. As the only egg-laying snake in the UK, they can lay up to forty eggs in sheltered spots such as compost heaps. Grass snakes are commonly found in England and Wales, especially near garden ponds, where they feed on amphibians and fish.

Smooth Snake – A Rare Species

The smooth snake is rare, found only in a few sandy heathland areas in Dorset, Hampshire, and Surrey. This protected species is part of reintroduction programmes, aimed at preventing its extinction in Britain. Smooth snakes are ectothermic, basking in the sun and hibernating from October to April. Males compete for females, who give birth to between four and fifteen live young in September.

Throughout 2024, grass snakes have been spotted at our Boardwalks and Hampton reserves! If you visit one of our public reserves, keep an eye out this spring as they emerge from hibernation to bask in the sun!

Remember to report your sightings on our free Dragon Finder app.

What our animals are doing this month

February 1, 2025 by Admin

Written by Charles Bonnett, Transforming Lives Trainee

It’s February and we’re settling into the New Year. For our animals, February can represent a period of transition, as the first signs of spring start to stir them from their dormancy.

For some amphibians, February marks the beginning of their habitual migration to their breeding ponds. Male common frogs typically arrive first, ready to attract females. In warmer, southernly regions of the country, mating may have already occurred by late February and frogspawn may be present. Likewise, during warm, wet evenings, common toads will begin their migration to their ancestral breeding ponds; these epic journeys can sometimes span kilometres. Some of our three native newt species, smooth, palmate, and great crested newts, will similarly begin to rouse from their dormancy, though will likely remain more inconspicuous than their frog and toad counterparts.

In comparison to amphibians, our reptiles are more temperature-sensitive, and so will mostly maintain their dormant state throughout the cold February days in order conserve their energy. Though, this does not mean that reptiles will be completely inactive during this period; a warm spell may stir adders and common lizards from their inactivity, after which they may be seen basking on south-facing slopes to regulate their body temperature in preparation for spring.

Generally, there is a degree of variation in when a member of a species may exit brumation, in part influenced by regional variation in weather, where earlier activity may be observed in more southerly regions. A further notable impact on this transition is our ever-changing climate. Our winters are becoming milder and less predictable, leading to our amphibians and reptiles exiting their dormant state prematurely. This early emergence can be dangerous, as it can leave the animals exposed to unpredictable weather, such as cold snaps. Likewise, it can cause the expenditure of energy during colder periods which may be difficult to recoup as sources of food will be rarer.

Overall, then, February can be a transitionary period from dormancy to activity for our amphibians and reptiles, and will likely continue to be with greater frequency due to our changing climate.

Remember to report any sightings of our species (including eggs and young) on our free Dragon Finder app.

Climbing salamanders: perspectives from great heights

January 1, 2025 by Admin

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.

Great crested newt activity while overwintering in ponds – Information request

January 1, 2025 by Admin

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.

Click for references

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.

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