Reptiles are more difficult to detect than amphibians. They are secretive, cryptic (camouflaged), and do not congregate to breed as amphibians do, so spotting them requires a bit of skill and knowledge of where to look for them. Their behaviour, and therefore the chances of detecting them, are also strongly controlled by weather and time of day, as well as season. Targeting survey visits to suitable conditions makes all the difference between seeing lots and seeing none. Survey requires effort dissipated over a wide area of habitat, looking for good basking spots, and detection skills improve with experience and knowledge of reptile habitat requirements. There are no easy ways of making population estimates, and for the National Reptile Survey, our primary concern is simply detecting reptile presence or absence reliably.

Realistically, it is impractical to survey an entire 1 km square, so we will need to focus on the areas of habitat most likely to support reptiles. This must be done sufficiently well to be confident of presence-absence for the whole 1 km square. Surveyors will therefore need to be able to recognise reptile-friendly habitat characteristics within their survey square, in order to target survey effort there. Such reptile habitat features may include: long grass, tussocky grass, heathland, moorland, bog, scrub, bramble, dense herbs, uneven and undulating topography, sunny banks/slopes, forest rides, woodland edges and glades, habitat edges (ecotones), brash piles, manure/compost heaps, rubble/rubbish, derelict/brownfield areas, allotments, private gardens, roadside verges, railway cuttings and embankments, track and path edges, hedgerows, dry stone walls, rock/scree, habitat mosaics interspersed with moss/lichen patches and bare ground patches.

The survey visits will use visual search and refugia survey (if possible) to assess the presence or absence of each species, and gather information on habitat quality and future prospects of any reptile populations encountered.

Rather than attempting to calibrate for the complex effects of weather variation, surveyors will be trained to choose optimum conditions for survey, and to fit visits into appropriate weather windows. We considered standardising other variables such as distance walked along a fixed route, but rigid rules would be difficult to enforce, and probably off-putting to many people. Surveyors will therefore be allowed flexibility (within reason) to choose the time spent, distance walked and methods used. They will be asked to identify the percentage cover of likely reptile habitats in their square, and the proportion actually surveyed. By asking surveyors to record these variables, we can quantify the effort applied, and hope to be able to weight the reptile detection results accordingly.

Survey visits should target sunny or bright weather, on days that are warm but not hot. The middle of the day is best earlier in the spring, but mornings become better later in the spring. If all possible species were to be detected on the first visit, no more visits would be necessary (although they would be useful to help us assess how detectability varies between visits). If all species are not detected, a second and third visit will have to be made. Additional visits can be made throughout the spring, summer and autumn if the surveyor wishes, as these additional data will be useful. This is particularly so if you lay artificial refugia, as they ideally need to be in place several weeks before survey takes place.