It’s not all dinosaurs, killer eagles, blue whales, vampires and giant feral cats you know… as planned, I did spend Wednesday evening out in the field looking for newts (for the purposes of this discussion, newt = any member of the amphibian clade Salamandridae that is aquatic during the breeding season). Admittedly ‘the field’ may not quite be the appropriate term, as the newts we were searching for were a rumoured population reported to inhabit an ornamental pond in the middle of Southampton city centre. It’s great, the way people look at you, as you march through an urban area with your torch, fishing net and boots….
However, we did find the newts and, despite my high hopes that we might discover a wayward population of introduced Bosca’s newt Lissotriton boscai or Italian newt L. italicus, they turned out to be one of our commonest species, the Smooth or Common newt L. vulgaris. It’s an attractive little beast and always fun to watch, especially at this time of year (when they’re breeding and in their aquatic phase). The ‘we’, by the way, is myself, Phil Budd and John Poland [see image below]: we all represent the Southampton Natural History Society (Phil is chairman), but John is also chairman of the Hampshire Amphibian & Reptile Group.
It wasn’t exactly surprising to find that the colony consisted of Smooth newts. As I’ve now said several times (see Britain’s lost tree frogs and Hunting green lizards in Dorset), Britain is crap for reptiles and amphibians. We have just three newts, though one additional species is present here as an introduction (Banks 1989, Wisniewski 1989, Beebee & Griffiths 2000). Our biggest newt is the Great crested newt Triturus cristatus, sometimes termed the Northern crested newt by those outside of Britain, and referred to in shorthand as the GCN by those in the British herpetological community. Reaching 16 cm, it may be twice as big as a Smooth newt, and its dark brown colour, silvery tail flash, warty skin texture and enormous serrated dorsal frill make it unmistakable (females lack the tail flash and frill of course).
Occurring throughout northern Europe (but not Ireland or northern Scandinavia), it is most numerous in Britain where we not only have the highest number of breeding ponds (about 18,000 according to a 1989 estimate), but the biggest populations (a colony near Peterborough in Leicestershire apparently includes over 30,000 adults). Sadly however, it is clearly declining across its range and is thought to be the fastest-declining British amphibian or reptile. The 1981 Wildlife and Countryside Act (WCA) makes it illegal to harm, kill or trade in Great crested newts, to disturb, handle, possess or collect them, and to intentionally disturb the places where they occur. You need to hold a license to catch or handle them therefore. In practise however this doesn’t mean much, as not only do breeding pools get filled in by developers who are – allegedly – unaware of a newt colony’s presence, there are also loopholes (such as pre-existing planning applications) that allow the destruction of newt habitat (Griffiths 1996, Beebee & Griffiths 2000).
Europe’s newts are well known for their elaborate breeding appearance and complicated courtship rituals. Males may grow special fringes or webs on their toes, filaments at the tail tip, and elaborate dorsal crests, and they combine these features with brightly colored undersides. They only grow these secondary sexual characters after entering the water and resorb them when the breeding season ends. The sexual dimorphism present in European newts is among the most pronounced of all amphibians [adjacent GCN image from here].
Newt courtship is well known, well studied, and oft-recounted in herpetology books, so you may feel like you’ve heard the following all too many times before. During the breeding season, a male initiates courtship by pursuing or getting in front of a female; assuming she doesn’t swim away, he then begins displaying to her. He fans his crested tail in her direction, apparently in an effort to waft pheromones all over her, and as the display proceeds he may perform whipping, flicking, wiggling, rocking, and head-bobbing actions. Some of the postures adopted by the males of some species are known as ‘flamenco’, ‘cat-buckle’, ‘flurry’ and ‘whiplash’ (Arntzen & Sparreboom 1989: for more information on these display details go here). Some species perform hand-stands and present their bodies and crests in full lateral view to the female. The smaller newt species tend to use delicate, dextrous tail movements, while the big species use violent lashing of the tail: in the ‘whiplash’ action the male’s tail is repeatedly lashed across the female’s head and body. If the female remains interested, the male ends the display by turning away from the female and slowly moving off. She follows, her nose touching his tail, and he then releases a spermatophore – a sperm-filled gelatinous packet – on the substrate. The male then has to manipulate the female so that she continues moving forward, but doesn’t move so far forward that the spermatophore fails to contact her cloaca. All going well, contact is made and the spermatophore adheres.
All of this highly visual displaying requires an uncluttered, open display area, and newts may therefore not be able to breed in ponds that become choked with vegetation. Having said that, the smaller species seem relatively well able to attract and display to females in well-vegetated ponds, and this probably explains why their crests are smaller and less flamboyant that those of the big species. Furthermore, some of the smaller species (including the Palmate, Italian and Bosca’s newt) seem to rely more on pheromones in courtship than the large species, and are equipped with longitudinal ridges on their bodies that seem to help direct the wafted pheromones. There is also no evidence that males among the smaller species make, or stick to, a special display stand: they apparently wander about the chosen pool, and may even move from pond to pond in quest of females [adjacent photo shows - I think - a female Palmate newt from a Southampton garden pond].
For the big flamboyant species things are different: they do require special display stands, and they may stick to, and defend, special open areas on the pond floor. The males not only display to females, but to each other, and in fact male vs male displays are more common than male-female displays in some species (Hedlund & Robertson 1989). Males may tussle with and bite one another over dispute for a display area. This territorial aggression and choice of open display areas means that newts might be classified as lek breeders: a lek is an aggregation of breeding males, attending by females primarily for the purposes of mating. Leks are well known for birds (such as grouse, manakins, hummingbirds and snipe) and are also formed by a few mammals, including Fallow deer Dama dama, some antelopes, Hammer-headed bat Hypsignathus monstrosus and Walrus Odobenus rosmarus (Hoglund & Alatalo 1995). They aren’t the preserve of mammals and birds, as various frogs, crabs, flies and assorted other animals lek too.
Not all male vs male interaction in newts is aggressive however: some of it is covert. In several species, including Smooth and Great crested newt, some males mimic females. They pretend to be interested in a displaying male and, like a sexually receptive female, wait transfixed by his display, and then follow him and snout-nudge his tail when he begins to move off for the spermatophore transfer. A female that was genuinely watching the displaying male may then be led away by the mimic, who then gets the female to absorb his spermatophore (Verrell 1984).
After discovering the Smooth newt colony, we pressed on to another location to check the newt population there. For several reasons I will opt not to reveal the location’s name. Searching by torchlight around the edge of a large barren lake, we discovered that both Smooth and Palmate newts L. helveticus were present at the site. The Palmate newt is Britain’s smallest species (reaching 9.5 cm), though it’s not the smallest of all European newts, being exceeded by the 8-cm Italian newt L. italicus. Endemic to western Europe (though Ireland lucks out again, as does central and southern Portugal and Spain), breeding male Palmate newts possess only a very low, unserrated crest and possess black webbing on the hind feet and a filament at the tail-tip. Palmate newts also possess an unspotted pinkish throat and shallow grooves on the top of the head.
In the adjacent photo, we aren’t deliberately humiliating the Palmate newt that’s being handled, at least not intentionally, but examining its feet for signs of the metatarsal tubercle that is also diagnostic for this species.
Whether Britain’s herpetofauna is crap or not, I will maintain, as usual, that what little we have is still worth getting to know. I mean – come on – frill-crested amphibious salamanders that perform hand-stands and cat-buckle displays, waft pheromones over their breeding females, form leks, and indulge in ‘sexual interference’ (Verrell 1984). I’m sorry, but that’s amazing.
Refs – –
Arntzen, J. W. & Sparreboom, M. 1989. A phylogeny for the Old World newts, genus Triturus: biochemical behavioural data. Journal of Zoology 219, 645-664.
Banks, B. 1989. Alpine newts in north east England. British Herpetological Society Bulletin 30, 4-5.
Beebee, T. & Griffiths, R. 2000. Amphibians and Reptiles. HarperCollins, London.
Griffiths, R. A. 1996. Newts and Salamanders of Europe. T & A D Poyser, London.
Hedlund, L. & Robertson, J. G. M. 1989. Lekking behaviour in crested newts, Triturus cristatus. Ethology 80, 111-119.
Hoglund, J. & Alatalo, R. V. 1995. Leks. Princeton University Press, Princeton.
Verrell, P. A. 1984. Sexual interference and sexual defense in the smooth newt, Triturus vulgaris (Amphibia, Urodela, Salamandridae). Zeitschrift Fur Tierpsychologie 66, 242-254.
Wisniewski, P. J. 1989. Newts of the British Isles. Shire, Aylesbury.