Tin Tipping, Transects and Creep & Peep.
Many techniques can be employed for reptile surveys but the most commonly used by ecologists is the transect walk between several ‘artificial cover objects’ (ACO’s) or refugia, tiles, tins, felts or mats. Reptiles are attracted to the warm microclimates created beneath objects like these. Their food items are attracted also, making hunting easy. They can warm up without exposing themselves to the outside world and its host of predators. Early mornings will often see reptiles basking on top of these refugia. Though they can quickly disappear beneath the tin if disturbed.
The preferred ACO in herpetologist circles is the good old corrugated iron sheet. They are durable, weather in nicely, warm up quickly and retain the heat well. The disadvantage is the weight, difficulty in cutting to size and danger of injury from sharp edges. If you can find old rusty sheets lying around take a cheeky peek under them, you might just see one of our region’s four native reptiles (don’t forget to report what you see!)
The corrugated iron sheet above is well placed with plenty of dense vegetative cover surrounding it and a few inches of cut vegetation as bedding beneath. This allows reptiles to thermoregulate while remaining protected and under cover.
Onduline or Coroline is a rubberised material sold in DIY stores for shed roofing etc. It is generally black so it absorbs a lot of heat quickly and is heavy enough to stay in place most of the time. Unfortunately domestic animals will attempt to eat it and, being made of rubber, it’s quite difficult to cut to size.
This refugium has no surrounding cover in the form of dense vegetation and is lying almost on bare ground as the grass has been closely grazed by sheep. Moving over open ground to get to and from this refugium exposes reptiles to danger and the lack of bedding beneath means its usage would be limited as it would get too hot to stay under.
It is facing South however, which is good for reptiles, it’s located on a small bank angled towards the sun with the corrugations running horizontally allowing reptiles to nestle into the grooves safely if basking on top.
Roofing felt and carpet tiles can also be used as artificial cover objects, they tend to be light weight and again domesticated animals will sit on them, eat them and generally be a pest around them. They are very easy to carry onto a site and easy to cut to size. The larger the better for snakes, about a metre square (for those of you watching in black and white that’s about a square yard). Something in and around 60cm x 60cm would suffice for lizards (or 2′ x 2′ for those of you stuck in the dark ages).
The first thing to consider before laying out tins or any other refugium is landowner permission.
DO NOT go out and scatter refugium about the county without first finding out who owns the particular bit of land you’ve chosen. Some people might actually think it’s a good idea to have a reptile survey. Other might not, so please be respectful.
Place your tin sheets in clusters in suitable habitat in positions where you can see them using binoculars from a decent distance. This allows you to scan them for basking reptiles before you get too close. Once placed, leave them for several weeks to allow your scent to dissipate. Then plan out your transect route between tins and groups of tins. Creep and Peep your way along your route from tin to tin using visual surveying to spot reptiles who haven’t read the text books and don’t use tins. Carefully look under each tin once you’ve established there are no basking animals on top.
TOP TIP: Do not visit too often as disturbance will chase off any reptiles over a period of time. Professional ecologist only average about 7 visits during a survey over a season. Once a month is quite often enough.
The commonest things you encounter are ant nests, rodents and young toads, who seem to tolerate remarkable heat beneath the tins. If you are very lucky then you may even get a North East reptile. I have to say they are notorious for not using tins.
John R Grundy
Revealing Reptiles Project Officer