The Natterjack Epidalea calamita (introduced in the previous article) is a remarkable animal, well adapted for the dry, relatively saline environments it inhabits (there are places where Natterjacks inhabit saltmarshes, moors, and disused industrial areas). A proficient burrower, it starts digging a burrow with its forelimbs but does most of the work with its hindlimbs (hindlimb burrowing is typical for anurans, whereas forelimb burrowing is highly unusual). The burrows help the toads to gain access to moisture in dry habitats because they typically extend down to damp sediments; a particularly absorbent patch of granular skin on the animal’s belly enables it to make the most of damp sediments when they’re encountered [adjacent photo by kind courtesy of Neil Phillips].
The Natterjack runs rather than hops, and runs around at night in rapid pursuit of ants, moths and other arthropods. During this nocturnal foraging, some individuals range far and wide (for their size), but others are far more sedentary: foraging ranges might be as small as 50 square metres, or might be 20 or more times this size. Some individuals are highly site-specific and show remarkable homing instincts. Beebee & Griffiths (2000) report that individuals transported 500 metres away from their home burrow ‘into areas they have never seen before have been found back in their original burrow within a fortnight’ (p. 106). It’s still not known exactly how the toads are able to navigate so successfully [adjacent image shows Natterjack pair in amplexus, from wikipedia].
In Britain, the Natterjack is most common on the Irish Sea coast between Merseyside and the Solway Firth, and in the coastal areas of Norfolk and Lincolnshire. The species has declined catastrophically across the country and is now locally extinct across most of its range, mostly due to habitat loss. Its isolated presence in southwest Ireland has resulted in a lot of speculation – it’s even been suggested that it might have been introduced, either by humans or by birds (how the hell is that supposed to work?) – but the commonest idea has been that it’s a member of a relict Lusitanian fauna that evidences former links with Portugal. Rowe et al. (2006) showed that there was no genetic evidence specifically linking Irish natterjacks from those of the Iberian Peninsula, and that the Irish population had not persisted through times of Pleistocene glacial maxima: instead, it must represent an expansion from a north European clade that occurred more recently than 10,000 years ago (more recent than the coldest phases of the Late Pleistocene, but pre-dating the formation of the English Channel). The surprising discovery of a large Irish Natterjack population in the late 1960s (on the north side of the Dingle Peninsula) raised new suspicions of human translocation efforts, but recent work on genetic variation in Irish Natterjacks supports the view that this is actually a native, in-situ population (May & Beebee 2009) [adjacent picture of German Natterjack by Christian Fischer, from wikipedia].
Outside of the UK, the species occurs widely across Europe, being found in 21 countries across western, northern and east-central Europe. The Iberian Peninsula might be regarded as its stronghold; it is rarer and more sparsely distributed around the fringes of its range (the British Isles, Sweden and the Baltic states). It’s absent from Italy and the Balkans. There are no recognised subspecies.
With the European common toad and Natterjack out of the way, I’m going to stick with the theme of looking at ‘familiar’ Northern Hemisphere species in the next article. After that, things get increasingly obscure…
- Toadtastic – the invasion begins!
- Bidder’s organ and the holy quest for synapomorphies
- Our sex lives in words and pictures (or, On the reproductive biology of the Bufonidae)
- Skulls, crests, snouts and giant poison glands: the heads of toads
- Toads of the world: first, (some) toads of the north
For previous articles on hyloid anurans see…
- Britain’s lost tree frogs: sigh, not another ‘neglected native’
- Ghost frogs, hyloids, arcifery.. what more could you want?
- Green-boned glass frogs, monkey frogs, toothless toads
- It’s the Helmeted water toad!
- Horn-headed biting frogs and pouches and false teeth
- More wide-mouthed South American horned frogs
- We need MORE FROGS
Refs – -
Beebee, T. & Griffiths, R. 2000. Amphibians and Reptiles. HarperCollins, London.
May, S. & Beebee, T. J. C. 2009. Recent introduction or ancient ancestry? Use of genetic evidence to investigate the origins of range edge populations in natterjack toads (Bufo calamita). Conservation Genetics doi: 10.1007/s10592-009-9805-4.
Rowe, G., Harris, D. J. & Beebee, T. J. C. 2006. Lusitania revisited: a phylogeographic analysis of the natterjack toad Bufo calamita across its entire biogeographic range. Molecular Phylogenetics and Evolution 39, 335-346.