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Introduction to reptiles

Adder © Dave Jarema

There are four native reptile species in the region: two snakes, Adder Vipera berus and Grass Snake Natrix natrix, and two lizards, Slow Worm Anguis fragilis and Common Lizard Zootoca vivipara. None are widespread and all are restricted to particular habitats, predominantly upland. Adders, Slow Worms and Common Lizards are often found in the same locations. The Common Lizard is the most frequent and well distributed; the Grass Snake, which is at its northern limit here, is much the rarest and the most local. All four species are declining in the region. Preferred habitats and regional distributions for Common Lizard, Adder and Slow Worm have many similarities and these are described in the Common Lizard account, whilst the differences are discussed in the Adder and Slow Worm accounts.

Sea turtles very occasionally occur when unusual sea conditions bring them from the Atlantic into the much less suitable North Sea. Most of the turtles reported along our coasts have been caught in fishing nets or washed up on the beach sick, injured or underweight. A Hawk’s Bill Turtle Eretmochelys imbricate was caught in fishing nets off the mouth of the Coquet in 1852, exhibited at Berwick-upon-Tweed and later sent to London. A male Leathery Turtle Dermochelys coriacea was caught in the nets of the fishing boat Avail off Berwickshire, Scotland, in October 1980, and landed at Eyemouth. It was taken by lorry to Oban aquarium and later released (Den Hertog, 1984). Another Leathery Turtle was caught on 30 August 1999 a mile off Roker, Sunderland, but died shortly afterwards (British Marine Life Study Society, 2012). Changes in North Atlantic currents may bring more of these turtles into the North Sea in future.

Like amphibians, the small, fragile bones of reptiles are rarely retained in the fossil record. All four of our native species have probably been present since post-glacial times. Grass Snakes may have had several regional extinctions and re-colonisations as the climate has changed. There is the possibility that the European Pond Terrapin Emys orbicularis may once have been present in our region and then become extinct. Its sub-fossil remains from 6,000 years ago have been found in Norfolk (www.cgoecology.com, 2012).

Sand Lizards Lacerta agilis are native to Britain but not to our region. They may have been unofficially released at various points on Northumberland’s sand dunes and on both sides of the river at Teesmouth at several times, but appear not to have survived for very long. The North East coast probably has summers that are too short for this species to breed successfully. Inland records of Sand Lizards, of which there are several, are almost certainly mistakes for Common Lizard. Common Lizards photographed by Derek Hornsby at Annstead Dunes in 2007 showed remarkably large, green specimens that could easily be confused with Sand Lizards.

Non-native species of snakes are often reported, sometimes misidentified as Grass Snakes. Corn Snake Elaphe guttata guttata, King Snake Lampropeltis getula and Garter Snake Thamnophis spp. seem to be able to survive in the wild, at least in the warmer months, though they are unlikely to over-winter. A Garter Snake has survived from May to September, at Ryton, but was not seen the following year. None have become established in the region. These escaped pet animals are often much more easily seen and approached than wild native reptiles.

Red-eared Terrapin Trachemys scripta elegans is our most frequent alien reptile species. Released as unwanted pets, a total of up to 100 of these North American terrapins have been recorded at a number of easily accessible, urban ponds across the region. They survive well, growing quite large, hibernating successfully and living for many years. A female was found laying eggs at Shibdon Pond near Blaydon in 1992 (Bowie and Durkin, 1995). They are known to breed successfully at similar latitudes in Denmark and in the Netherlands, but not in Britain. They have declined in popularity as pets and it is now illegal to import this species, though other similar species can still be imported. Fewer are now being released but there are still a small number of long-term survivors in the wild. There may occasionally be other similar terrapin species released as well as Red-eared.

Since 1998 regional maps of the distribution of the records of our reptiles have been periodically published (Durkin, 2010B). All of the native reptiles have legal protection under the Wildlife and Countryside Act, and Sand Lizard and Smooth Snake have fuller protection under the European Species and Habitats Directives (English Nature, 2004).

by John Durkin