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Great Crested Newt

Great Crested Newt by Terry Coult

The Great Crested Newt Triturus cristatus is the largest of the three native newt species, often up to 12 cm and occasionally up to 17 cm long. Females are larger than males. Newts of 17 cm have been recorded at Hett in County Durham and at the former Choppington clay pits in Northumberland. In keeping with its alternative name of Warty Newt, the skin has a warty texture, distasteful to predators. The upper surface is black or very dark brown with darker spots while the newts are in the water, blacker and unspotted in terrestrial animals. The underside is usually “number plate yellow” with dark spots, sometimes merging into stripes or blotches. These are very variable between individuals and so photographs can be used to distinguish animals for “mark and recapture” population studies. Rarely, in the North East, the background colour can be a creamy yellow, lemon, orange or orange-red. There are usually many fine white spots along the flanks of mature animals.

In the aquatic phase males have a jagged crest along the body with a distinct notch before the less jagged tail crest begins. The tail crest is usually symmetrical above and below the tail. There is a pale central tail stripe that may have silvery and/or blue tones. Aquatic phase females lack the dorsal crest, tail crests and the pale central tail stripe but have a distinct yellow stripe along the lower edge of the tail (Jehle, 2011). Variations are rarely found in the region but include neotony, red underside, milk-chocolate brown dorsal side, exaggerated crests starting at the tip of the nose, and dwarf mature animals.

The British newt species breed continuously through the spring and summer, so that while there is a peak period in April and May, there are usually always some breeding adults present from March to September. This contrasts with the one-off, intensive spawning of frogs and toads. Great Crested Newt eggs are laid singly in a folded leaf and are about four to five mm across, compared with Smooth Newt Lissotriton vulgaris and Palmate Newt Lissotriton helveticus eggs, which are about three mm. The size and stiffness of leaf used is related to how readily the female newt can fold the leaf between her back legs, so larger, stiffer leaves with eggs enfolded are more likely to be from Great Crested Newts. The aquatic efts, or larvae, have a striped tail and have a tail filament like an adult male Palmate Newt: this is absent in Smooth and Palmate larvae (Green, 2001). Efts hatching late in the year have over-wintered in the aquatic phase in recent mild winters, apparently more often than is the case with the smaller species.

Great Crested Newt ©

Terrestrial efts are similar to terrestrial adults but smaller and with fewer black spots on the underside. The word “eft” is related to the old word for newt, with the “n” of “an eft” moving to the second word, “a neft” and later “a newt”. Curiously, this has happened the other way round with “an adder”, originally “a nadder”. The word “nadder” is related to the scientific name of the Grass Snake, “Natrix”.

Great Crested Newts have a lowland distribution in all of the counties of northeast England, corresponding roughly to the cereal farming zone, with the main populations between the A1 and the coast. Numbers and densities decline northwards. Local distribution is quite patchy, with several strong concentrations associated with areas of high density and high quality of ponds. Less attractive ponds that would not be occupied if they were isolated may be occupied if there are good ponds nearby and/or the ponds form a cluster with linking terrestrial habitats between them. Lowest population densities are in urban areas, upland areas and areas of low pond density. The first major study of Great Crested Newt sites in our region was carried out by Dave Green in 1984 but since then Great Crested Newts have often been surveyed for as part of planning applications or for nature conservation. Probably more than 75% of Great Crested Newt sites in the region are now on record because of this.

West of the A1 their range is very patchy. They are generally absent from moorland and upland areas but there are two interesting exceptions to this. In north Northumberland there is an important population at Quarryhouse Moor, where an isolated population is found in a cluster of ponds in a disused limestone quarry at an altitude of 210 metres. In County Durham there is an upland population in long disused stone quarries on Knitsley Fell, at around 310 metres. This population seems to be spreading into a number of small ponds in Hamsterley Forest (Durkin, 2010A).

MARS Great Crested Newt

Trends over the last 20 years have been for a reduction in the number of ponds occupied by Great Crested Newts, with losses in our region of the order of 1% per year (calculated from the baseline of Dave Green’s 1984 surveys). The main adverse factor has been the stocking of ponds with fish for angling. This has particularly affected the larger ponds. Fish have also been introduced to Great Crested Newt ponds casually or accidently, particularly after nearby ponds have been stocked deliberately. Much less frequently fish may arrive naturally, for example during flooding. The second main factor has been natural vegetation succession, where a pond ceases to carry water for long enough in the summer to enable successful breeding to take place. The dry springs of the first decade of the 21st century have accelerated this loss. The third main factor has been the complete loss of Great Crested Newt ponds by drainage and/or infilling, often on agricultural land.

However some new sites for Great Crested Newts have also arisen with the creation of larger than average garden ponds, often with deliberate introduction of newts and exclusion of fish. This has restored the species to some urban areas from which it had been lost. There have also been many attempts at providing new ponds for Great Crested Newt, some as compensation for the loss of existing ponds due to developments. These have had very mixed results, usually fairly poor but with some notable successes, such as at New Hartley near Blyth and Daisy Hill, adjacent to Waldridge Fell. Climate change may be aiding Great Crested Newts, with a possible expansion of range at the northern and upland edges of their distribution.

Surveys for Great Crested Newts use a number of techniques; in ponds these include netting, torch survey after dark and looking for eggs, in ponds and for terrestrial newts looking under logs and rocks. The best method is by “bottle trapping”: placing plastic bottles with inverted funnels into a pond overnight so that they act like lobster pots. This technique needs training and a licence as it is easy to harm the captured animals (Gent and Gibson, 1998; Langton, 2001).

The Natural England Site of Special Scientific Interest (SSSI) assessment criteria for this species are for animals counted by torchlight. Fewer than 10 is “Low”, 10 to 100 is “Good”, and over 100 is “Exceptional”. For counts in daylight, or netting, these numbers are halved (Nature Conservancy Council, 1998). Daylight counts are rarely used as pond conditions can make these unreliable. The criteria have been in operation since the 1980s and so do not take account of the more modern technique of bottle trapping, which is now usually accepted as the most reliable method of population assessment. There are particularly large Great Crested Newt populations at New Hartley, Coxhoe Ponds, Pity Me Carr, Ramside Golf Course, Cowpen Bewley, Elementis (Stockton) and Carlin Howe.

In 80% of ponds where Great Crested Newts are present Common Frogs Rana temporaria and Smooth Newts are also present. Smooth and Palmate Newts are present in most of the other 20% of Great Crested Newt ponds. Common Toads Bufo bufo may also be present in the larger ponds.

Very few ponds have Great Crested Newt as the only newt species, or have Great Crested Newts with Palmate Newts but not Smooth Newts.

In ponds with a mixture of newt species the proportions vary quite considerably. Great Crested Newt are only rarely the most common species, and often the least common, but they can occasionally account for 80% of all newts present.

by John Durkin