#96 Slow Worm by John Pemberton
Meet John Pemberton, Sustainable Environment Manager at East Riding of Yorkshire Council!
John works for East Riding of Yorkshire Council as Sustainable Environment Manager overseeing natural environment policy and nature recovery. In his spare time John is a volunteer reptile surveyor for the Amphibian and Reptile Conservation Trust and Yorkshire Amphibian and Reptile Group with a particular interest in the remnant slow worms of the Wolds and the Grass Snake population of the River Hull Headwaters. Following a career focussed on overseas conservation and reptiles of the shelled variety, his return to the UK resulted in a chance encounter with the Kent Reptile and Amphibian Group and from there the passion for British reptiles grew. Now as a resident of the East Riding I’m very concerned about the challenge reptiles face in the county.
John can be reached via email at sustainable.development@eastriding.gov.uk, on Bluesky @teuchternature.bsky.social and on LinkedIn https://www.linkedin.com/in/john-p-b2a9a91b4/. To find out more about the Local Nature Partnership in Hull and East Yorkshire, visit their website: www.heylnp.co.uk.
Slow Worm, James Mortimer
The English vernacular of many species’ names are wonderfully misleading and none demonstrate this better than common Slow Worm Anguis fragilis, as most reading this will know it is certainly not a worm, and, as John could tell you from first-hand experience on a warm day, they are not particularly slow! The species component of its Latin name however is more accurate, ‘fragilis’ arising from the readiness which it will drop its tail when restrained, a physiological process common within lizards called autotomy. Slow Worms are a legless lizard, one of 5 extant species of its genus globally. By British standards, adults can get relatively large, up 50cm in length although 30cm is more usual for a mature individual. At first glance they appear fairly monochrome grey, but colour variations can and do occur as does sexual dimorphism. Males are generally monochrome grey all over, whereas females show countershading with a dark underside and often striped ventrally. Males however can exhibit startling blue flecks which appear to be more common in specific populations and there have been very occasional records of males which are almost cobalt blue in colour. Juveniles however, affectionately known as “noodles” are stark in their countershading, showing no sexual dimorphism and resembling females in their sub-adult phase.
Little is known about longevity in the wild, but they are long lived animals. To get to adult size takes a number of years, so 10-20 years plus is likely common and an individual in Copenhagen Zoo is known to have lived to the grand age of 54. Older animals of both sexes, but particularly females, tend to exhibit scarring, particularly around the head and neck as mementos of the particularly rough mating process shown by the species.
You can find out more about the Slow Worm on the NBN Atlas: https://species.nbnatlas.org/species/NBNSYS0000005072.
Slow Worms are probably the most adaptable of Britain’s reptile species in terms of habitat selection and across most of the country is the reptile most likely to be seen by the public due to their propensity to exist in parks and gardens where they should be welcomed as a voracious predator of many soft-bodied invertebrate “pests”. In Yorkshire they are generally associated with heathland habitat and as a rule of thumb if Adders find the habitat suitable then Slow Worms do too, but it is likely that they are under recorded in other habitat types. They are equally comfortable in well managed woodland, grassland, road verges, allotments and gardens - anywhere where there is some vegetation structure and opportunity to bask. They are a species which requires the tangle of untidy vegetation and loose soil as a fossorial reptile. For John, his specific interest in the species has partly developed through seeing the species almost at will in his own garden for 8 months of the year, allowing him a real sense of how they behave, even to the point of recognising individuals.
Slow Worm being held (supervised!), Vaughan Grantham
In East Yorkshire, however, the species is largely thought to be absent. Records from the 1990’s show that they were still present in a number of market towns and in the 1970’s records exist from Hull and the Spurn peninsula. However, the species have likely suffered from the loss and fragmentation of habitat through development and intensive agriculture. That said there are still a couple of known populations in the East Riding and likely others unknown to recorders. A short hop over the border into North Yorkshire however and they are far more readily found both in towns and the rural landscape, although the recent wildfires around Scarborough may have had serious impacts at a local level. Within Yorkshire it is likely that they are a largely overlooked species, particularly in the wider rural landscape. In some parts of the UK they have some relevance to local culture but to a far lesser degree than species such as Adder. Slow Worms were mistakenly considered to be venomous, thought to stem from the “snap” sensation experienced when they drop the tail in a person’s hand which led to local names such as blind snake and blind adder (the species is certainly not blind!). Shakespeare’s inclusion of the “blind worms sting” as an ingredient in the cauldron of Macbeths witches is likely a reference to the tail of a Slow Worm.
Although a prey species for almost any mammalian or avian predator which can fit them in their mouth, Slow Worms appear to readily co-exist with Adders and it is not uncommon to find them residing under the same artificial refugia or amongst Grass Snakes in a compost bin. There also appears to be some association with ants, at least under refugia. This relationship with ants has long been considered it to be a benign one, possibly as simple as both exploiting warm refugia, but it has recently been suggested that the ants may act as a deterrent to Slow Worm predators as well as the more obvious suggestion of the Slow Worm exploiting locations where ants are present as a food source. The understanding of relationships with ants and other species under refugia is one area which the National Reptile Survey run by Amphibian and Reptile Conservation Trust, aims to better inform.
Nationally the Slow Worm is considered to be widespread and common and like the Adder and Viviparous Lizard gives birth to live young, an adaptation which allows it to extend into the north of Scotland. Unfortunately, the national picture also appears to be one of decline. In southern areas increasingly and hot and dry summers appear to be impacting Slow Worm distribution and survival as well as the more usual issues of habitat loss and the impact of non-native species such as Pheasant and domestic cats. Slow Worms and their soft bodied prey are also vulnerable to desiccation during prolonged periods of hot weather. Another impact of climate change appears to impact their reproductive behaviour. Many viviparous reptiles, the Slow Worm included, often give birth on alternate years due to the physiological stress of the process. It appears that the added stress of hot dry summers may be resulting in fewer offspring or less frequent birthing years. As such, northern populations could become more important from a national perspective and understanding the distribution of Slow Worms in Yorkshire, particularly those persisting alongside development and agriculture is important. The species is slow to move across the landscape but will do so readily when suitable habitat is present. For the Slow Worm success really is dependent upon two simple things - connectivity and tangled vegetation. Everything else is a bonus.
For John, part of the allure of the Slow Worm, and reptiles more generally, is the excitement of catching a glimpse of them in the wild: ‘Given the relative paucity of reptile species in the United Kingdom there is always a degree of excitement and a touch of the exotic when one is seen. I’m often struck at how blissfully unaware the public are when I’ve been watching a Slow Worm, Adder or Grass Snake and people walk by without having any idea that they have just brushed past a reptile. For me, this all adds to the sense of excitement and privilege when one is spotted. There is also something of the sense of unknown about them. Almost all interactions are in one of a small number of scenarios; individuals basking, individuals bolting after being disturbed or individuals under refugia. Outside of these moments very little of their life, and particularly Slow Worms, are well understood or easily observed. All of this just adds to the sense of mystery which keeps me coming back for more.’
Slow Worm, image from Pixabay
Recording and monitoring
If you spot a Slow Worm, you can record your sighting via The Record Pool, which is an online recording tool set up jointly by Amphibian and Reptile Conservation (ARC) and Amphibian and Reptile Groups of the UK (ARG UK): https://www.recordpool.org.uk/index.php
If you are interested in volunteering to monitor Yorkshires reptiles the Amphibian and Reptile Conservation Trust run the National Reptile Survey and Yorkshire Amphibian and Reptile Group can provide support.
Further information and acknowledgements
NEYEDC would like to thank John for his time and expertise in helping to create this blog.