Getting to Know the Natterjacks

Today was the Wildlife Recorders’ Conference at Tullie House Museum in Carlisle, which was a fantastic event that I learnt a lot from. The day consisted of a series of talks from experienced recorders across a range of topics from beetles to upland lakes.

I often believe that I know quite a bit about our British wildlife, but when I attend an event organised by the Cumbria Biodiversity Data Centre I’m reminded that, compared to the wildlife veterans, I know absolutely nothing. It’s a sobering but also inspiring thought, to think that there is so much still to learn about the natural world.

One talk that particularly stuck with me was from Ruth Popely from the Amphibian and Reptile Conservation Trust, who told us all about natterjack toads (Epidalea calamita). This was especially interesting because the natterjack toad is a species I know absolutely nothing about, so everything I found out today was fascinating new information.

Natterjacks are typically greeny brown in colour with a distinctive cream stripe down their back, along with knobbly ‘warts’. They are poor swimmers and much prefer to run across even ground. For this reason, their favoured habitat is a barren one, with little protection from the elements. This may seem like a hostile environment that couldn’t possibly be resourceful, but in fact the natterjacks have pulled a clever move. Not only does flat, short ground vegetation provide the perfect runway for efficient mobility, but by living in a habitat that most would turn down, there is much less competition from other amphibians such as common toads.

The natterjacks have a few nifty tricks up their sleeves that help them survive their unforgiving habitat. They don’t drink water, but instead use drink patches on the undersides of their bodies as sponges to soak up water and stay hydrated.

The toads’ ability to burrow allows them to stay sheltered in the colder winter months. When the time to breed arrives in April, the males begin producing rasping noises using their blue vocal sacs, a feature absent in females. Once the collective din reaches the females – sometimes from as far away as a kilometre – they join the party at the water.

Natterjacks breed in shallow, temporary bodies of water, another feature that separates them from common toads who choose deeper, permanent aquatic areas. Therefore, as the tadpoles only have limited water availability, they need to grow rapidly into toadlets. The natterjack has often been regarded as a boom or bust species due to its risky breeding technique. Some years, if the rainfall is infrequent, the tadpoles run the risk of becoming beached or isolated in too small a body of water. However, if conditions are good, they are very successful breeders. To reduce the impact of a bad season, females can spawn more than once in a breeding season, so in a single pond strings of spawn, tadpoles and fully metamorphosed toadlets can all be found on the same day.

Naturally, there are threats to the natterjacks’ welfare. Land management has reduced both their aquatic and terrestrial habitats. This in turn leads to a loss of connectivity and increased isolation. Additional detrimental impacts include disease, predation and competition from other amphibians.

Natterjacks are rare in Britain, with a stronger hold in parts of Western Europe. Hopefully, if more people like me find out just how fascinating these little amphibians are they’ll get some well deserved attention and be around long into the future.

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