Photo: Great Crested Newt Larva (photo by:By Piet Spaans (Own work) [CC BY-SA 2.5], via Wikimedia Commons)
The GCN is easily distinguished from the other newts by its 17cm size as well as its bumpy and very dark skin colour. The underside of this species is yellow/orange with large (generally un-uniform) blotches leading to its dark under chin. Breeding males (March-June) have a jagged crest along its back, as well as having an iridescent strip on its tail, used for mating displays. The female’s yellow/orange belly extends through to its tail. When identifying the GCN it is also important to take into account the species at different life stages, where it may be more difficult to identify.
Due to their protection status, it can make it difficult to directly identify a GCN and to be sure they are present. A commonly used method to assess the likelihood of GCN presence is a Great Crested Newt Habitat Suitability Index (GCNHSI). This method looks at 10 factors to indicate the liklihood of having GCN present:
Each factor is assessed and converted to be between 0.01 - 1.
Once the 10 scores allocated they are then multiplied together, the tenth root of this number is then calculated: HSI = (SI1 x SI2 x SI3 x SI4 x SI5 x SI6 x SI7x SI8 x SI9 x SI10) ^(1/10). The result should be somewhere between 1-0, giving the liklihood of GCN on being present within a waterbody.
You should record the presence of protected species on a national database. This can done by contacting the local Statutory Nature Conservation Organisation (SNCO). Alternatively you can record online at the National Biodiversity Network. You should also alert the appropriate land owner, council and or management body to the presence and location of this species.