Tetrapod Zoology

The Natterjack, its life and times

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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].

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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].

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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…

For previous articles on hyloid anurans see…

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.

Comments

  1. #1 David Marjanović
    October 28, 2009

    by birds (how the hell is that supposed to work?)

    Same way as always: by eggs sticking to feathers of waterbirds.

    Given the distances involved, however, that ought to lead to desiccation and death, I suppose.

  2. #2 Darren Naish
    October 28, 2009

    Yeah, as you surmise, epizoochory just cannot work for toads: their eggs can survive out of water for, at most, a few hours, and even this would be exceptional.

  3. #3 Dartian
    October 28, 2009

    Outside of the UK, the species also occurs in Germany, France, Spain and Portugal

    The natterjack is a bit more wide-ranging than that, actually. It’s found as far north as southern Sweden and Estonia, respectively, and as far east as Belarus.

  4. #4 Darren Naish
    October 28, 2009

    Thanks, I’ll correct.

  5. #5 Dartian
    October 28, 2009

    It’s absent from Italy and the Balkans.

    The natterjack’s distribution is actually quite interesting. It seems* that certain mountain chains such as the Alps, and possibly the Carpathians, have been unsurmountable biogeographical barriers to its dispersal. And yet the natterjack has succeeded in bypassing the Pyrenees (in whichever direction). It would be interesting to know if there are other European anurans, or other microvertebrates, that show a similar distribution pattern.

    * ‘Seems’ being the operative word.

  6. #6 Dartian
    October 28, 2009

    unsurmountable

    insurmountable. *Sigh!*

  7. #7 retrieverman
    October 28, 2009

    I can’t wait until you get to the North American toads.

    Where I live there are two similar species–the Americantoad and the Fowler’s toads–and they are very hard to tell apart.

    They also hybridize.

    In fact, American toads, Fowler’s toads, Woodhouse’s toad, and the Southern toad have all been known to hybridize where the ranges of two species overlap.

  8. #8 Adrian Thysse, FCD
    October 28, 2009

    An interesting series of articles. I have some photos of Bufo borealis at my site – found in the Alberta Rockies, a juvenile with orange toes.

  9. #9 Blackbird
    October 28, 2009

    I used to dig for fossils in Miocene sands in SE Spain, beautiful Scutella and Clypeaster sea urchins. The area is dotted with salt lakes. Often deep down a hole, we’d come across a Natterjack. I was always surprised of how deep the dig their holes. Also, they are thought to have survived through glaciations in the Iberian Peninsula and migrated north through possible two routes E and W of the Pyrenees – coastal, most likely. Therefore their grographic distribution

  10. #10 Craig York
    October 28, 2009

    Natterjack is a wonderful name, but I’m a lttle vague on
    what it signifies-some relation to how it vocalizes?

    I was also surprised that it runs rather than hops. I’d
    never heard of this in frogs or toads before, and I gather
    its fairly uncommon.

  11. #11 Neil
    October 28, 2009

    Ah the humble little natterjack. I was dead chuffed when I finally saw one (even though it was captive) in the New Forest Reptile centre. I yet to see one in the wild.

    I read an interesting paper on their conservation where they had dug out their breeding ponds to stop them drying out but these started to be used by other amphibians which out competed the poor natterjacks. It turns out the natterjacks need pools that are to difficult for others to survive in i.e those that dry out or become inundated by sea water for many of the years, removing the competion and in the few good years the natterjack numbers would be sustained by their large numbers of young.

  12. #12 retrieverman
    October 28, 2009

    Does anyone know the etymology behind the word “Natterjack”?

    Is this a British English word? As far as I know, it doesn’t exist in American English.

  13. #13 pomposa
    October 28, 2009

    @ Craig York and retieverman;
    “A natterjack” could well be a misdivision of “An atterjack” just as “A newt” is a corruption of “An ewte”. Cf “attercop” (poison-head), the old name for spider.

  14. #14 Adrian Thysse, FCD
    October 28, 2009

    Regarding Craig York’s comment, the Boreal toad is also more inclined to walk rather than hop.

  15. #15 John Opie
    October 28, 2009

    On a birdwatching trip to Norfolk a few years ago I was amazed by the noise coming from the field behind the house where we were staying. Thinking it was from some bird we had yet to see I checked with a local naturalist. “Hell no, that’s the Natterjacks”.
    The next evening there was one on the doorstep!
    They ARE quite noisy.

  16. #16 Will Baird
    October 28, 2009

    A little video of a Natterjack running:

    http://www.youtube.com/watch?v=9DHpqYj4zDI

  17. #17 Will Baird
    October 28, 2009

    And another:

    http://www.youtube.com/watch?v=9DHpqYj4zDI

    How salt resistant are they, btw?

  18. #18 Dartian
    October 29, 2009

    Will:

    How salt resistant are they, btw?

    It varies. In Spain, natterjack salinity tolerance differs widely between different populations (the most tolerant will breed in brackish water*). And even the least tolerant Spanish natterjack populations have shown higher salinity tolerance than any British natterjack populations studied thus far (Gomez-Mestre & Tejedo, 2005).

    * ‘Brackish water’ is, of course, a relatively broad concept as it covers a pretty wide range of salinity regimes (at least from a lissamphibian’s point of view).

    Reference:

    Gomez-Mestre, I. & Tejedo, M. 2005. Adaptation or exaptation? An experimental test of hypotheses on the origin of salinity tolerance in Bufo calamita. Journal of Evolutionary Biology 18, 847-855.

  19. #19 windy
    October 29, 2009

    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?)

    It seems that they also disperse by means of salad bags.

  20. #20 Dartian
    October 29, 2009

    It seems that they also disperse by means of salad bags.

    Would that be a case of sainsburochory?

  21. #21 David Marjanović
    October 29, 2009

    Is this a British English word? As far as I know, it doesn’t exist in American English.

    Well, the species doesn’t occur in America, so…

    It seems that they also disperse by means of salad bags.

    :-D :-D :-D

    Would that be a case of sainsburochory?

    What about epiphytochory?

  22. #22 Darren Naish
    October 30, 2009

    The word ‘Natterjack’ is apparently derived from both ‘naedre’ (an Anglo-Saxon word meaning ‘nether’ or ‘lower’) and ‘jager’ meaning ‘one who runs’. Adder is also apparently a corruption of naedre: it seems that the word was used widely for creatures that crawl or run around close to the ground. The loud calls of Natterjacks have inspired various local names such as Thursley thrush and Birkdale nightingale, and they’re also called running toads and golden backs in parts of the UK. All info from Beebee & Griffiths (2000).

  23. #23 Darren Naish
    October 30, 2009

    For a better video of a running Natterjack, try this (though the toad runs out of steam about halfway through).

  24. #24 David Marjanović
    October 30, 2009

    Interesting. German Jäger = “hunter”.

    Lots of videos to watch for the weekend…

  25. #25 Sven DIMilo
    October 30, 2009

    Wow…I’ve seen Bufo boreas walk (a lot!), but when they really want to escape, they’ll hop. I’ve never seen a toad run like that! Very cool.

  26. #26 Sven DIMilo
    October 30, 2009

    the toad runs out of steam about halfway through

    damn anaerobic glycolysis..

  27. #27 Dartian
    November 30, 2009

    A bit late for this natterjack party, but here goes…

    Darren:

    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)

    and Blackbird:

    they are thought to have survived through glaciations in the Iberian Peninsula

    Not that this solves the question of the origin of the Irish natterjack population, but there is at least some direct evidence of the presence of Bufo calamita relatively far north in Europe* during the very latest Pleistocene/Holocene. According to Holman (1998), fossil B. calamita remains of probable Holocene age are known from at least two localities in England (Cow Cave, Devonshire and Whitemoor Channel, East Cheshire, respectively). And, still according to Holman, late Pleistocene, or possibly Holocene, natterjack fossils are also known from Neubrandenberg, northeastern Germany. In other words, either B. calamita was not entirely restricted to the Iberian Peninsula during the last glacial maximum, or else it spread north from there very rapidly.

    * No fossils are known from Ireland, unfortunately.

    Reference:

    Holman, J.A. 1998. Pleistocene Amphibians and Reptiles in Britain and Europe, Oxford University Press, New York and Oxford.

  28. #28 Dartian
    November 30, 2009

    Sorry, I meant to write Epidalea calamita. I got stuck in the nineties for a moment there…

  29. #29 David Marjanović
    November 30, 2009

    Neubrandenberg

    I bet that’s -burg.

  30. #30 Dartian
    November 30, 2009

    David:

    I bet that’s -burg.

    You’d have won that bet. (It was wrong in the original and I didn’t double-check…)

  31. #31 Peter Mudde
    August 27, 2010

    It might be funny to mention..
    natterjacks are considered endangered species in the Netherlands and therefor protected as well. In the last few years several building-enterprises had to be stopped because of that. there were found natterjaks on the buildingsite. It just happens to be that building sites ( al least in the Netherlands where there such a site is usually first covered with a mter of sand) are perfect breeding habitats for Natterjacks. Newly build projects are among the best sites to find them here. When I moved into my house in 1990 you could find tens of natetrjacks runnig around on a rainy night, Now the sand is overgrown, Gardens are lush and shady. Not much of a habitat for natterjacks. They are now rather rare even if there are still some (4 or 5) living in my garden.

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