John W. Wilkinson and Peter Hill, Amphibian and Reptile Conservation      Reviewed by Steve Head

 

 

In recent decades, British farming has had to become more “efficient”, and countryside and semi-natural habitats are being lost and fragmented due to infrastructure and other development. Gardens are becoming increasingly important as habitats for amphibians and other fauna with limited dispersal availability.

 

 

Amphibians are the frogs, toads and newts that use ponds for breeding in the spring. There are only seven species native to Britain and gardens provide important habitat for five of them. Amphibians have moist thin skin, and are not equipped to resist prolonged dry conditions. While they have lungs and breathe air, many can take in enough oxygen through their skins when in cold water. As cold-blooded animals, their activity and metabolic rate is governed by the ambient temperature, so all hibernate in winter.

 

The two groups of amphibia in Europe are  the Urodeles – the salamanders and newts with long swimming tails, and the Anura, the more recently evolved tail-less frogs and toads

 

Amphibians are sometimes considered “canary species” refererring to the old use of canaries in coal mines, where the birds were far more sensitive than people to firedamp and declining air quality, and so gave early warning of problems.  Amphibians have thin moist and soft skins very sensitive to pollution.  Their two-stage life cycle requires both healthy freshwater habitat nature and a sustainable terrestrial environment. If either deteriorates enough, amphibians won't survive - so giving early warning of environmental problems.

 

Globally, amphibia are in decline.  This is probably due to many factors - including their sensitivity to environmental deterioration, but also including widespread habitat loss, and a series of lethal diseases, especially Chytridiomycosis caused by the fungal pathogen Batrachochytrium dendrobatidis and Ranavirus, caused by one or more large DNA viruses in the Iridoviridae.

 

Four of the British amphibians are of sufficient concern to be listed as Biodiversity Action Plan species, and two of them, toads and great crested newts, can be found in gardens.

 

 

Left: Garden frogs mating, the smaller male clasping the female firmly behind her arms - this state is called amplexus, and can last for hours or days until they are ready to spawn.

 

Above right: Frogspawn, the black egg surrounded by an expanded protective mucus envelope.

 

Below right:  Frog and toad tadpoles.  The larger paler ones are frogs, and the smaller darker ones are toads.

Common toads Bufo bufo are frequent garden residents and most often use this habitat as summer and autumn foraging ground. They will also visit the pond for a soak but breed in gardens less frequently than do frogs, preferring larger, deeper water bodies, ideally >500m² and >0.5m deep.  Toads are more tolerant of fish than other garden amphibia. Fully grown toads can grow to 15cm and are much bigger than frogs which may reach 9cm.

 

The toad life-cycle is similar to the frog’s, but the eggs are laid in long dark ribbons attached to weed. In general they are more fully land-adapted than frogs, and more resistant to drying out.  With shorter hind legs they don’t jump in the way that frogs do, but crawl energetically if they have to.  Their skin contains distasteful toxins that make them relatively free from predators.  Toads can live for 10-12 years (much longer in protected captivity), and are mature at about 4 years old.

 

Like frogs, toads have a long sticky tongue which can be shot out suddenly to catch food. Toads feed on insects and their larvae, spiders, slugs and worms. Big toads may be able to eat small reptiles and mice.

 

Toad numbers have declined by two thirds in the last thirty years, and they are UK Biodiversity Action Plan species, and protected in law.

 

 

 

 

 

 

Newt life cycles closely resemble those of frogs and toads, but their metamorphosis is less dramatic because they retain their swimming tail as adults. They breed in the spring, and males grow breeding displays of crests.  Although adult newts are less weighty than frogs, their larvae are predators on frog tadpoles.  Quite often, as newt populations grow in garden ponds, the garden frogs seem to disappear.  Smooth newts in the wild live for about 6 years, maturing at 2-3. Great crested newts can live as long as 16 years in the wild, and much longer in captivity.

 

Breeding success can vary greatly from year to year, especially in great crested newts which have been studied more thoroughly.  Whole annual cohorts can be eliminated by ponds drying up, or by introduction of fish, while in some years survival rates can be exceptional.

 

On land, newts feed on slugs, snails, worms, spiders and insects.  In the pond they eat small crustaceans and insects, and pond snails which they wrestle from their shells.  In turn, newts are eaten by foxes, badgers, hedgehogs and several predatory bird species.

 

 

All amphibians perform a useful garden role in eating the slugs, snails and other invertebrates that are the bane of many wildlife gardeners who prefer not to use chemical pest control. If you’re planning a wildlife pond and want to encourage amphibians

 

•site your pond in a sunny spot away from overhanging trees and shrubs

•include gently-sloping sides to allow young amphibians to enter and leave the pond easily

•try to include a section at least 60cm deep in which frogs can hibernate without being frozen

•create about 30% cover of a mixture of aquatic plants, and surround the pond with marginal 

      plants.     

•avoid adding any fish.

 

The terrestrial habitat provided by the garden is also important for amphibians – they will be attracted by insects in flowery borders as well as patrolling vegetable plots for pests. A rough area with logs or boards in a quiet corner will provide hiding places where they can spend the day. Bog gardens and shaded densely vegetated areas help in dry periods, and rockeries make ideal overwintering habitat.  When newly metamorphosed frogs leave the pond in late summer, be very careful when mowing the lawn not to destroy them, and if you can, give them time to disperse to flower beds and rough ground.

 

Our pages on pond ecology and management starting here.

Our summary of amphibian preferences for pond types.

Natural England leaflet on amphibia

 

 

 

The two smaller (c 10cm) species of newt – the smooth newt Lissotriton vulgaris and palmate newt Lissotriton helveticus  are happy breeding in small garden ponds. Which species you may get depends on whereabouts you live and what the local geology is like – palmate newts do better in slightly more acidic ponds and are commonest in heathy or upland areas. Some people are lucky enough to find both species using their pond and may even have great crested newts Triturus cristatus if the pond is large enough and free of fish. Great crested newts are more selective in their breeding pond needs, preferring medium to large ponds, >0.5m deep, and without fish, but use gardens where conditions are suitable. 

 

If you do have great crested newts you should be aware that while they are very fine looking creatures, and an asset in any garden, they are highly protected under section 9 of the Wildlife and Countryside Act, and in Regulation 39 of the 1994 Habitats Regulations. This severely limits what you can do if they are breeding on your land (normal pond maintenance should be ok) and you can find a summary of what you can and can't do here.  Froglife's 2001 "Great Crested Newt Conservation Handbook" is still a very useful and complete reference to the species.

 

 

Above left: Toad showing the characteristic irregular warty skin and short hind legs that distinguish them from frogs.

 

Above right: Resentful toad captured in a garden in which it was coming to the end of hibernating.

 

Below left:  Typical long strands of toad spawn.

Male great crested newt.  Note the fine jagged dorsal crest (less obvious out of water), and particularly the bright yellow on the belly. These newts grow to 15cm long and are much chunkier than the smaller common and palmate newts

Half grown great crested newt tadpole showing the persistent external gills at the same time as the developing front legs.  Frog and toad tadpoles lose their external gills much earlier, and their hind limbs appear before their forelimbs

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Toad numbers have declined by two thirds in the last thirty years, and they are UK Biodiversity Action Plan species, and protected in law.

 

 

The common frog Rana temporaria frequently uses garden ponds for spawning, and the juveniles and adults live in and around the garden throughout the year, sometimes (particularly the males) hibernating in the pond.   They are found throughout Britain and Ireland, and are considered to be declining, along with most of the rest of our fauna. Garden ponds are extremely important for frogs, and suburban populations largely depend on them.

 

Breeding starts in late winter/early spring, with the males arriving at the pond first, to get first-pick of the females. As climate change is becoming noticeable, the first frogspawn is now seen before Christmas in the south-west of Britain.

 

Frogspawn swells after laying, becoming clear transparent globules through which you can see the black embryo inside, and follow its growth. The hatched tadpole larva is very fish-like but equipped with feathery external gills, and feeding on algae.  As they grow, tadpoles  develop first hind legs, then front legs,become carnivores,  start breathing with lungs (as well as through the skin) and finally reabsorb the tail. With metamorphosis complete, the tiny juvenile forgs emerge from the pond and start life on land. The process from egg to emergence takes about six months, but is very temperature dependent, and adult frogs are able to mate in their second or third year.

 

Adult frogs eat insects, worms snails and slugs, which they catch with their long sticky tongues. They in turn fall prey to a number of predators including grass snakes, herons, otters, mink cats and rats.

 

British frogs are under threat from Ranavirus (once called red-leg disease) an amphibian virus that weakens and kills them, and is highly infectious.  Symptoms include redness of skin with ulcers, bleeding, emaciation and lethargy.  There is no cure, but populations affected can rebuild numbers in subsequent years. This is one reason why we do not recommend transferring frogspawn from one pond to another, in case the infection is spread with the spawn.

 

 

 

 

 

In recent decades, British farming has had to become more “efficient”, and countryside and semi-natural habitats are being lost and fragmented due to infrastructure and other development. Gardens are becoming increasingly important as habitats for amphibians and other fauna with limited dispersal availability.

 

 

Amphibians are the frogs, toads and newts that use ponds for breeding in the spring. There are only seven species native to Britain and gardens provide important habitat for five of them. Amphibians have moist thin skin, and are not equipped to resist prolonged dry conditions. While they have lungs and breathe air, many can take in enough oxygen through their skins when in cold water. As cold-blooded animals, their activity and metabolic rate is governed by the ambient temperature, so all hibernate in winter.

 

The two groups of amphibia in Europe are  the Urodeles – the salamanders and newts with long swimming tails, and the Anura, the more recently evolved tail-less frogs and toads

 

Amphibians are sometimes considered “canary species” referring to the old use of canaries in coal mines, where the birds were far more sensitive than people to firedamp and declining air quality, and so gave early warning of problems.  Amphibians have thin moist and soft skins very sensitive to pollution.  Their two-stage life cycle requires both healthy freshwater habitat nature and a sustainable terrestrial environment. If either deteriorates enough, amphibians won't survive - so giving early warning of environmental problems.

 

Globally, amphibia are in decline.  This is probably due to many factors - including their sensitivity to environmental deterioration, but also including widespread habitat loss, and a series of lethal diseases, especially Chytridiomycosis caused by the fungal pathogen Batrachochytrium dendrobatidis and Ranavirus, caused by one or more large DNA viruses in the Iridoviridae.

 

Four of the British amphibians are of sufficient concern to be listed as Biodiversity Action Plan species, and two of them, toads and great crested newts, can be found in gardens.

 

 

 

 

Left:  Smooth or common newt. Above: Palmate newt.  They are very similar, but the palmate newt lacks the spots under the throat which the common newt shows clearly.

 

 

 

 

 

 

 

 

 

 

Page drafted by John W. Wilkinson and Peter Hill, Amphibian and Reptile Conservation      Reviewed and edited by Steve Head

 

 

 

 

 

 

 

 

 

 

 

 

Page drafted by John W. Wilkinson and Peter Hill, Amphibian and Reptile Conservation      Reviewed and edited by Steve Head