This method is based on the Reptile pilot surveys carried out by the National Amphibian and Reptile Recording Scheme NARRS in 2006 (see references for NARRS website).
Please read this safety information before carrying out a survey.
Reptiles are active during warmer weather in the spring and summer months and therefore it is important that monitoring activity is carried out during this time. The best time to carry out survey work is during warm days in the spring when reptiles start to emerge from hibernation (from February to May).
To maximise the chances of locating any reptile species that are present, it is recommended that more than one visit is made to the survey site each year. It is recommended that 3-5 visits should be made during the key survey period in the spring. If desired, further monthly visits could be carried out in summer and autumn to monitor reptile activity at the site during this time.
When deciding on the frequency, you should bear in mind that the same number of visits will be required in future years to analyse trends. When repeating the survey in future years, the survey dates should be chosen so that they match as closely as possible with the previous year, but it is more important to ensure that the weather conditions are suitable for reptile surveying than to ensure that surveys are carried out on exactly the same dates annually.
• Route map/survey forms/refugia
Two methods are described. The first requires the laying of refugia on site to attract reptiles to shelter underneath them. This is the recommended method where it is possible to safely lay refugia in areas of good habitat on the site, as it greatly increases detection. If it is not possible to lay refugia at the site (e.g. due to security, safety or cost concerns), then a visual search can be carried out using a set route.
Both methods could also be combined (undertaking a visual search on a set route whilst checking the refugia).
Method 1 – Laying and checking refugia
What are refugia?
Refugia are simply sheets of corrugated iron sheets (‘tins’), corrugated roofing sheets (trade name: Onduline), or roofing felt that are laid out at a site to attract reptiles that shelter underneath them where it will be warmer than the surrounding area.
Roofing felt is the cheapest and simplest option and can be more easily transported. However, it is the least effective material for attracting reptiles (other than slow-worms). Snakes and lizards do use roofing felt, but less so than Ondulin, with metal being most effective.
Most people use sheets or tins that are roughly 1 × 1 m in size, although smaller sheets (e.g. 50 × 50 cm) or larger sheets can also be used.
When should I use this method?
This method is best used for private sites where the owner has given permission to lay refugia and where there are no safety or security issues. Careful consideration would be needed before using the method on more open sites where the refugia could be disturbed, moved or even removed completely.
In order to use this method, it is important that the refugia can be evenly distributed in all areas of good habitat (or a representative selection where habitat is extensive). Normally, most surveyors should be able to transport, lay and check around 20-30 refugia (assuming metal tins), although more could be used if necessary to fully cover suitable habitat.
How do I identify suitable habitat?
Undertake initial visit to identify and map habitat. Available habitat data from GiGL can form a preliminary desk study.
Refugia should be evenly distributed in all areas of good habitat, such that they can be checked on a fixed survey route (bearing this in mind when laying them). The location of each refugia should be mapped with a grid reference (GIS could be used to give an exact location), and given a unique identifying number used for all future recording.
Checks should be carried out during warm (not hot) weather. These are carried out very simply by following the predetermined route and carefully lifting up the refugia to count any reptiles found underneath them.
The refugia number and the numbers of each species seen (if any) should be immediately entered onto the survey form that is carried into the field. The refugia should then be replaced in exactly the same position.
Method 2 – Visual searches
As a result of their behaviour, reptiles can be very difficult to observe in the field and therefore visual searches may result in very low counts or zero counts even when they are present at a site. The skill levels and experience of different surveyors is likely to vary considerably and counts will reflect this. If visual searches are to be carried out, there is a need for good training and guidance, including ecological notes and photo-guides on habitat preferences, and tips for spotting reptiles and improving fieldcraft. It is advisable that all surveyors receive such guidance from an acknowledged expert before using this method (see references and links)
Selecting a route
The route chosen should take in as many areas of good habitat as is it can. Where the habitat is widespread and accessible then a straight line transect can be followed. The most important consideration is that the route can be easily followed again on future visits and in future years so it should make use of features such as footpaths and obvious landmarks.
The route should be recorded on a map as precisely as possible so it can be recalled the following year or if the surveyor changes. The length of the route will vary depending on the time available and the number and location of suitable habitat pockets.
When selecting a route, you should bear in mind that walking whilst surveying for reptiles will be considerably slower than a normal walking pace.
Carrying out the walks
Walks should be carried out during warm weather (details as above). The method is simply to follow the route looking for reptiles and counting the numbers of each species seen.
The route could be divided into sections to give an idea of where the reptiles are found on the site. If this is done then the number of sections should be limited and the boundaries should be clear. The sections should be marked on the map and the numbers of each species recorded for each section separately.
Where the route passes across wider habitat strips and areas of open habitat, visual searches can be carried out within a ‘buffer’ of 20 m either side of the route to aid detection, with all reptiles counted if seen within the ‘buffer’.