Sunday 23 February 2020

Natterjack Toads are very rare in the UK but breed in pools at the side of the road in Portugal

Natterjacks like temporary pools and puddles
Natterjack Toad (Photo by Bernard DUPONT)

The Natterjack Toad (Epidalea calamita) is one of the rarest amphibians in the UK and only found in several scattered colonies in coastal areas in England, Scotland and one in Wales where it has been reintroduced. It is the only native species of toad in Ireland where it lives in a few locations. In many parts of Europe, however, it is far more widely distributed, and in Portugal it even breeds in temporary pools and puddles at the side of the road near where I live.
Roadside pool (Photo by Steve Andrews)
Pool with tadpoles (Photo by Steve Andrews)
Unlike the Common Toad (Bufo bufo), which likes large ponds and lakes, the Natterjack uses pools that are likely to dry up later in the year. This is a great danger for its tadpoles because the water may all evaporate before they have grown big enough to become toadlets and to leave. Many tadpoles perish when the pools become no more than cracked mud. Lucky ones will be in pools with deeper water that takes longer before it has all gone. There is an advantage to this seemingly reckless breeding behaviour though, because the pools the Natterjack chooses have no predators, such as newts and dragonfly nymphs in them. The Natterjack actually favours pools that do not even have any vegetation, and are just a few inches of water covering sand or mud. Somehow they manage to find enough to eat in these conditions.
Natterjack Toad Tadpoles (Photo by Steve Andrews)
The tadpoles are much smaller than Common Toad tadpoles too and they can complete their metamorphosis in as short a time as six weeks. It is a race against time when warm weather dries up the water they depend on. Last year, where I live, this species was unlucky because drought set in with hot sunny weather and all the pools dried up totally. I had moved some of the tadpoles to pools with more water but even my effort to help them was in vain because none of tadpoles had even developed their back legs when all the water was evaporated in the heat. This year, I am hoping that some, at least, will survive. We have had a lot or rain earlier on and the temporary pools where I find tadpoles of this species currently still have plenty of water, although it is starting to go down. In the UK, the Natterjack is mainly found in coastal locations where temporary ponds form in dunes and sandy areas by the sea, on the continent and Portugal, however, it is also found inland. The male Natterjack attracts others of his kind to a suitable stretch of water with a loud and rasping call but only does this at night. By day, these toads hide in burrows in the sand, and they favour sandy locations, such as dunes and heathland.
The Natterjack can be recognised because it has a yellow stripe down the middle of its back. It cannot jump well and tends to walk fast, which has led to it also being known as the “Running Toad.” When I was a boy I always dreamed of finding a Natterjack Toad but never did. It was very rare all those years ago too. I am amazed to find this very rare amphibian breeding in muddy pools by a main road near where I live.

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