The main threat posed to newts in Europe is that of habitat loss. Newts require waterbodies surrounded by adequate terrestrial habitat, in order to support both phases of their life. If either of these two habitats is damaged, a population may not be able to survive. Ponds in Europe are disappearing rapidly, and few countries have strong legal protection for their ponds.
Existing ponds may also become degraded, and unable to support good populations of newts. The natural process of succession may lead to ponds being overgrown with reeds, rushes, shrubs or trees (and in parts of the UK, alien succulents of the genus Crassula).
Predation may also be a factor involved in decline in newt populations. Fish, in particular, are important predators of both adult and larval newts. Predation by introduced fish may already have led to the extinction of T. alpestris lacusnigri (Vogrin, 1996). Larvae of T. marmoratus and of the cristatus group are particularly susceptible, as they spend most of their time in the water column, rather than on the bottom. Pesticides have been successfully used to eradicate fish for newt breeding sites, although these must be used in winter, when the newts are not in the water.
Collection for the pet trade has been accused of causing declines in newt populations, but the actual magnitude of the effect is unknown. The larger, more vividly marked species (especially T. marmoratus, T. cristatus, and T. carnifex) have been common in the trade in the past, although tighter restrictions on collection and export in the European Union have now led to a decrease in the trade in wild-caught specimens. Since the collapse of the Soviet Union, there has been a sharp increase in the export of live wild-caught animals from the ex-Soviet states, and T. vittatus has been exported regularly, along with occasional imports of T. karelinii, T. montandoni, and T. alpestris.
HOW TO HELP
Existing ponds need maintenance, and local conservation bodies will advise on projects in your area.
Surveying is needed, both to locate unrecorded newt populations, and to monitor existing ones.
One of the best ways to help newts, if you have a garden, is to build a pond. Even a small garden pond may support some of the smaller species; in particular, T. vulgaris does very well in gardens. A shallow, well-planted pond is ideal for newts, so long as there are no fish in it (see above).
To avoid depletion of wild populations, anyone desiring to maintain captive newts should only buy captive-bred stock. All of the Triturus species are bred by private breeders in Europe, and the large numbers of eggs and larvae produced mean that young newts are often available relatively cheaply.
FIELDWORK WITH NEWTS
The easiest way to locate newts in the wild is to visit ponds during the breeding season. This is usually in spring, though newts may be present much earlier in the year, and the season can be very protracted, so this may well cover a period of several months. Newts are generally nocturnal, and so to see active newts, one may have to visit the pond at night. Newts can often be observed by shining a strong torch into the water; this may allow breeding behaviour to be observed, and can certainly help give an estimate of numbers present. Nets can be used to sweep weed beds to capture newts in hiding; when using this technique, one must be careful not to damage plant growth. In addition, this may infringe the law if protected species are netted.
Underwater bottle traps have been used to capture newts, but these must be used with care, and regularly checked, as the newts in the traps cannot come to the surface to breathe. Pitfall traps combined with drift fencing have also been used to monitor newts arriving at ponds at the beginning of the breeding season.
Netting may also locate larvae. This can be helpful later in the season, as larvae may be present until late summer. Identification of larvae may be problematic, so further visits in the spring may be necessary to properly identify the species present.
Eggs may also be found, by looking for the characteristic bent leaf the female has folded over an egg. Some tentative identification may be possible at this stage. In the UK, this technique has been used to confirm the presence of crested newts.
The British Herpetological Society publish a number of leaflets relating to reptile and amphibian conservation, and their conservation committee is active in conservation in the UK.
The Biological Records Centre maintain a database of location records for reptile and amphibian species in the UK, and publish maps of the distributions of these records. Record cards are available from them for contributing your own data.
Vogrin, N., 1996. An Overview of
the Herpetofauna of Slovenia. British Herpetological Society
Bulletin 58: 26-35.