In the past, several methods of surveying have been used for great crested newts such as visually looking for eggs, searching for individuals at night, using torches or even temporarily trapping individuals to identify them. All of these methods have various benefits and draw backs but can be fairly time-consuming and often need to be repeated several times under specific conditions to obtain reliable results.
eDNA sampling is a fairly recent method approved by Natural England and currently being used for great crested newt surveying. It is much more efficient in terms of the time taken to carry it out and can provide very clear results when enquiring into the potential presence of newts. eDNA or environmental DNA is nuclear or mitochondrial DNA that is shed from an organism into their environment. Although this may sound complex, it is fairly easy to find and can be released into the environment through several ways such as the shedding of skin cells, saliva or even faeces. Detecting this eDNA can allow you to see what species has been present in an area without having to physically find the animal yourself. In an aquatic area such as a pond, eDNA can become heavily diluted and spread out so it is recommended to take 20 samples of water from different areas of the pond to increase your chances of collecting it successfully. eDNA is often heavier than water and can sink towards the bottom of a water body so it is a good idea to collect water close to the bottom to increase your chances of finding it even more. eDNA can persist in water for up to 21 days so even if newts have not visited the pond for several weeks, you will still be able to determine that they have been there recently.