Being able to identify reptiles, guess their ages, tell the sexes apart, know what they feed on and give the life history of an animal is all well and good. But all those splendid abilities don’t count for much if you cant find them in the first place.
When asked to survey for reptiles and you are confronted with a vast open moor, miles of coastline or acres of wetland it can be a little overwhelming. Understanding the habitat will help narrow down where to look within a specific landscape.
Knowledge of what makes a habitat suitable for reptiles helps us to judge whether or not it’s worth looking at in the first place. What features does it have? Is it connected to other suitable habitats by features helpful to exploratory reptiles? Can populations expand easily throughout the landscape without running the risk of being predated or being flattened by vehicles? So much to think about.
Topography, Altitude and Aspect.
Our Northern reptiles are a hardy bunch and will occur at altitudes well above anything the Durham dales can throw at them. Common lizards and adders occur across Europe at higher altitudes than 3000m. Undulating land with a variety of contours offer micro-climates that provide shelter from wind. East, South and West facing banks and slopes of hills offer more basking opportunities. Further afield across Europe, where you may also encounter the same species as are found in the UK, you would look at similar situations. As mentioned above your search could take you higher into the mountains than Tow Law.
Climate & Weather
Reptiles love the sun! That’s a well known fun fact. Typically most people associate reptile sightings with holidays abroad. But our Northern herpetofauna will tolerate a mixed bag of conditions. Snow on the ground, mist and fog. Drizzle and even passing blizzard conditions on a sunny February morning wont put off a determined adder or common lizard from grabbing the rays. Or at least some reflected UV. Even the arctic circle has populations of adder and common lizard. I cancel planned surveys on days when it is snowing, raining or thick fog. Not because the chances of seeing anything are reduced (They are, of course, but not completely out of the question). But because it’s unpleasant for volunteers to be dragged round in these conditions.
All sorts and plenty of it. Vegetation mosaics are what you’re after. Mono-crops are less likely to support reptile populations than scrub land or other environments with a good mix of plant types. Conifer plantations and potato fields wouldn’t be my first choice of places to check but perhaps the forest edge or field margin would offer more opportunities. Reptiles will mosaic bask. This is their way of hiding from predators while soaking up the sun. They hide themselves in dense vegetation such as heather, tussock grasses, mounds of bracken or dense mosses etc. Often woven through the plants with only a cheeky hint of a coil or their face visible to the careful observer. Vegetation of different heights offers more shelter and basking choice as well as foraging.
As well as the undulating contours mentioned above and a good cover of plant life, there are things a good herpetologist can not walk past without checking over for little scaly baskers. Piles of logs, stone or rubble. Brash piles and heaps of cut grass or straw. Old stone walls and ruined buildings. Tree stumps or raised root plates from a partly collapsed tree. Wooden board walks, bridges and fences. The bottom rail of a post and rail fence and angled support struts are favourite common lizard basking spots. Compost, silage and manure heaps. Fly tipped rubbish especially doors, road signs or metal sheets, rubber car mats and black plastic bags. All these things catch the eye and provide basking and shelter for reptiles. This is why artificial cover objects such as roofing felt and corrugated tin sheets are used by herpetologists doing official surveys. They attract reptiles by providing shelter and warmth and make life easier for the surveyor.
Reptiles occupy a vital central link in a food chain. They eat many things smaller than themselves and are in turn eaten by a list of predators larger than they are. In order for a landscape to sustain reptiles it must also have a stable supply of predator and prey. They are regarded as indicator species by which ecologist and conservationists will determine the health of a given ecosystem due to the presence of or lack of a reptile population. Amphibians are also regarded in the same light. So if you expect to see snakes look out for signs of rodents or small ground nesting birds. For lizards you should notice the insects and spiders in the grass. Plenty of slugs might suggest slow worms are present.
Location & Connectivity
So take all the above into account and add them into a landscape and you could have the perfect place to observe numerous reptiles. However, is this place linked to other suitable habitats? How is it linked and what distances are we looking at? The more rural and remote you are the more likely hood of one place being in close proximity to another, with good corridors provided by water ways, hedges, walls or old paths and tracks. Ditches, rail lines and planted shelter belts and woodland blocks can all provide reptiles with the chance to migrate from one place to the next. This helps with breeding among populations as well as maintaining balance within an ecosystem by dispersal. Too many individuals of one species will possibly struggle to find enough shelter and food within a limited area.
It’s always worth looking into the history of a place to establish whether or not it has ever supported a reptile population. Old records may date back decades which can indicate once healthy populations. This could mean animals are still present but have gone unrecorded for many years, or that a population has declined. It is always worth visiting a site and looking at habitat and land use change. This could indicate why a species might no longer exist in an area. Old records and maps are always fascinating to look at anyway.