Nigel Hand, a professional herpetologist, has been at the forefront of UK reptile and adder conservation and research for over twenty years, developing a methodology of external radio transmitter attachment to track this relatively small snake. His monitoring reptiles and radio tracking adders has provided valuable insights into their secret habits and the issues they face in the 21st century.
Growing up in Stourbridge, in the heart of the West Midlands, adders were scarce in the industrial landscape, but grass snakes and smooth newts were always plentiful along the banks of the canal or the cut as locally known. In my Wollaston Secondary School I was fascinated to come across two freshly sloughed male adders in the woodland edge above the school playground, which rather shows how undisturbed and wild the edges of my school grounds were in the 1970s. I even dragged my teacher and class mates out to see them. More recently I checked out this area and although the woodland is still there the understory is well worn with paths, little undergrowth and could not be called wild – the adders are probably long gone.
Herefordshire has been my home for the last 30 years living a much more rural life and both my work and my passion is adder conservation. I want to see the adder thrive on the quieter hillsides and commons where it has lived for centuries. A shy and beautiful creature, living in the most undisturbed habitat, and Britain’s only venomous snake making support for it occasionally problematic, I fear I’m fighting a losing battle as their numbers continue to dwindle and their habitat issues become greater. One of these impacts is the cultivation and shooting of large numbers of the non-native ring neck pheasants on herptile species.
Many shooting estates have raised pheasants for over a hundred years and adders have been persecuted for longer still. An extract, from one of the earliest books on the adder, referenced gamekeepers killing adders on a Herefordshire hillside at the end of the 19th century, illustrating the extent of time these birds have been released into the countryside and the levels of prejudice and unwarranted fear.
‘The game keepers kill a considerable number of adders every spring (the woods on both Garway Hill and the Graig are heavily preserved with pheasants), but apart from that the adder population is very secure in the Monnow Valley’
Extract from the book ‘The Life History of British Serpents and their local Distribution in the British Isles’ by Gerald R. Leighton 1901 (Chapter 14 the Ophidia (Snakes) in the Monnow Valley page 203.)
Thankfully the adder is now protected by the Countryside and Wildlife Act 1981 schedule 9 from intentional persecution and injury but unfortunately not protected from steady decline and Leighton’s comment that ‘the adder population is very secure in the Monnow Valley’ is not the case any more.
A single shooting estate, near one of my long term SSSI monitored adder sites, releases 60,000 birds annually, along with many smaller local shooting syndicates also putting out birds, resulting in unnaturally high number of pheasants foraging across sensitive habitats.
The annual release of approximately 38 million (likely an underestimate) industry reared non-native pheasants is believed to be worth £350 million to the UK economy alone (Slade 2005; Aldous and Alexander 2008; DEFRA 2008).
The Game & Wildlife Conservation Trust (GWCT) recommends release densities not to exceed 1000 pheasants per hectare; however this is not enforced and is sometimes greatly exceeded with up to 5000 pheasants per hectare of release pen recorded’ (Sage, Ludolf and Robertson 2005).
‘The Midlands is a region of particular concern as the adder is in greater decline here than elsewhere and, to a lesser extent, slow-worm population declines are also evident. Many of the populations reported on were relatively small. A third of adder and almost a quarter of slow-worm populations were reported to consist of fewer than 10 adults.’
(English Nature Research report no 546 Baker et al 2004), (Gardner et al, Make the Adder Count population trends 2019)
Across Herefordshire and the vast majority of lowland Britain adders have become restricted and localised. They are now considered extinct in Nottinghamshire, Oxfordshire, Warwickshire and Hertfordshire. Many populations exist on islands of habitat, surrounded by intensive agriculture, urbanisation and busy roads preventing mixing of populations and making them extremely vulnerable to catastrophic events, but also suffering a slow decline in genetic variability.
In Herefordshire, Worcestershire and Gloucestershire the species exists in low numbers at a handful of sites. There is current work looking into the feasibility of reintroducing adders back to former habitats but if issues such as predation cannot be addressed this is going to be a wasted opportunity.
This ‘islanding’ of adders can also be due to non focused management, excessive site grazing and the removal of scrub and mature heath, which provides security, thermal gradients and linkage corridors for wider dispersal. Mature commercial conifer, with its lack of understory, open glades and ground cover has extremely limited value to adders and other reptiles. Adders prefer track and ride edges, favouring open fringe areas with nearby taller, structural habitat which they can retreat into on disturbance.
Adder sites have ‘hotspots’, usually hibernacula or thermoregulation areas, in early spring there may be a concentration of newly emergent snakes in these foci areas. This reliability and faithfulness to an area is particularly seen in female adders who may move only a few metres between the same bramble or gorse blocks over the course of a year. Adders favour gorse (Ulex sps), bramble (Rubus fruticosus), rough grassland, bracken (Pteridium aquilinum) and mixtures of these habitats and preferring sandy, acidic well drained soils rather than wet clays..
It is argued that managing woodland rides for gamebirds will result in favourable habitat management for a range of species, including reptiles, but if thousands of birds are annually released on or near vulnerable reptile populations this will not be beneficial.
Between 2008 and 2010 adders were monitored (Hand 2008-2010 report to Forestry Commission unpublished ). One of the best reptile areas was in a young private larch and conifer plantation and had a peak count (over a single day) of 52 adders. This was an exceptional site for the West Midlands with grass snake, viviparous lizard and slow-worm numbers also high.
After 2010 the woodland began to shade out and the landowner placed pheasant feed hoppers along remaining ride edges. As a consequence of both shading impacts and grain feeders attracting and holding pheasants the reptile sightings plummeted, so much so that only 4 adders were recorded in the 2019 survey year (S.Sheldon et al 1990-2019). It must be pointed out that the landowner did remove the feed hoppers when asked and attempted to cut back some of the larch and conifer, but so far it has not been enough and there has been no noticeable recovery to the originally high numbers here.
Surveying on the Warburg Nature Reserve SSSI adder site in Oxfordshire in 2011, to assess the feasibility of restoring and improving habitat for reptiles revealed that only one large female adder remained. No other adders were ever detected and the species is now considered locally extinct on this site. Warburg borders a shooting estate and although the actual demise of adders on this site cannot conclusively be put down to the impacts of a long term pheasant shoot, it is highly likely this does play a part. Any plans to return lost reptile species must consider the proximity of shoots that operate nearby with1000s of annual bird releases.
The decline and loss of a native species and even the complete loss of the Oxfordshire adder should carry a greater conservation importance. Adders can be long lived. Females only breed every two to four years and on average give birth 1.3 times per lifetime. The short reproductive life is a consequence not only of mortality directly related to the reproductive activities, but also of mortality associated with recovering from the weakened post-parturient body condition during the long intervals (1–2 years) between reproductive bouts. (Bauwens et al 2019)
Pheasants impact reptiles in a number of ways. Pheasants’ natural foraging behaviour has been seen to unsettle basking adders. I witnessed an adult male adder noticeably agitated by the close presence of pheasants, exhibiting deep rapid breathing and hissing behaviour. This was on bracken and grassland hillside during long term monitoring of a small and vulnerable population of 13 photo identified snakes. Pheasants, like many birds, are attracted to the reptile’s wriggling, sinuous movement and attack either as a predatory or as an inquisitive response. Snakes may even be perceived as a threat to broods by hen birds.
A recent article in the Scottish Courier newspaper (2017) showed this exact behaviour, although the paper described it a little differently “Remarkable moment Scots gamebird fought off venomous snake!”. The native adder is in reality attempting to flee from the predatory game bird. Video link
Reptiles are ectotherms meaning they must bask in the sun to warm their bodies for activity. The presence of game birds will reduce the length of time reptiles spend openly basking and vulnerable to disturbance and attack. This in turn could lead to health complications, reduced vigour and impacts to breeding with possible low recruitment into populations.
There are photos of pheasants eating wild reptiles, a juvenile grass snake was photographed being predated by a hen pheasant and the birds have also been recorded taking small rodents such as voles and mice and also invertebrates; all prey items of UK herptiles species. Many may believe that as the adder is venomous it can therefore defend itself, but this does not appear to dissuade these large birds who will attack and easily immobilise a full grown adder and seem able to avoid a venomous bite.
I have witnessed an attack on a 40 cm female adder by an adult cock pheasant on the Malvern Hills. The adder was left with serious damage to both eyes and head from its beak (see above) probably leading to a lingering death or predation. The question is how often is this happening across UK reptile sites. The pheasant was unlikely to eat such a large snake but the attack still immobilised and damaged the animal beyond recovery. My identification photos show adders and grass snakes with body and head scars, blinding, and also slow-worm and viviparous lizards with regenerating tails and scarring. This will not be solely down to pheasants but due to the sheer numbers of annual releases they are a serious concern.
Research into the impacts of pheasants on reptiles is difficult to assess because of the secretive nature of reptiles and typically low site carrying capacities. Recent DNA analysis of pheasant faecal samples failed to identify reptile DNA, even when DOR dead reptiles have been fed to captive birds on a research project. A pheasants diet in the wild is known to include reptiles, invertebrates, small mammals and amphibians. When feeding young captive pheasant poults reptile casualties, including roadkills, of grass snake (Natrix helvetica) and slow-worm (Anguis fragilis) (Westbury et al., University of Worcester, unpublished data) it was noted that the birds readily consumed the these and appeared to recognise it as a valued prey source. Group feeding behaviours changed with birds becoming competitive and attempting to chase those with the reptile morsel.
Each July and August pheasants are released from their pens and disperse away from the shooting fields and woods, often taking up residence on important wildlife areas even SSSI NNR. There are even pheasants being released on a few NNR and SSSI sites! The timing of pheasant releases coincides with the birth of native reptile species and on my study sites where the pheasants gather after release on the warmer south facing slopes no viviparous lizards or neonate adders are seen.
Pheasants appear to inhabit the same favoured ecotones or micro climates that reptiles occupy, south facing glades amongst early successional vegetation such as bracken, gorse and wooded fringe. Evidence of pheasant occupation on reptile sites is seen in dust baths, piles of droppings, nesting hens and lying up areas and are all frequently found on adder hibernacula and thermoregulation areas. Pheasants are even released on National Nature Reserves e.g. Whixall Moss in Shropshire, a sensitive bog heath habitat for wading birds, invertebrates and reptiles. Such rare sensitive habitats with declining species should be kept free of gamebirds and associated shooting impacts. To safeguard fragile species and habitats pheasants should be trapped and removed off wildlife reserves. Efforts should be made to prevent the birds from straying off shooting grounds.
The glut of gamebirds will potentially result in greater local concentrations of native predators including the common buzzard, carrion crow, magpie, fox and brown rat who will all predate adders. Corvids and rats are attracted to grain feeding areas in maize cover crops. Buzzards are a well known adder predator and the regular abundance of local pheasants, including plenty of roadkill, and climatic shift to milder winters influences predator survivorship, putting further pressure on already vulnerable reptile populations.
There needs to be much tighter regulation on pheasant release numbers. Landowners should have stock books to account for gamebird numbers, ideally having leg rings identifying a shoot to track roaming dispersal behaviours.
Remove and dissuade birds from nature reserves and important reptile landscapes and there needs to be greater research into pheasant impacts on herptiles.
The earnings from this industry are high,
but the actual importance of this game meat biomass in the UK food economy is
low. We are now much more conscious of ethical food production and carbon
footprints, but is this industry doing the same? Pheasants move between being under farming
regulations then switch to being wild birds with no regulations and no
monitoring of their affects.
I have been a rough shooter in the past, living off the land and growing my own vegetables, providing food for my family and only taking what I really needed, never a yearning to go on an organised pheasant shoot. This has now become a massive industry and far removed from the necessity of food for the table. Thousand bird shoots are there for those willing to pay.
The UK’s adders are slipping away, site carrying capacities low, optimal habitat limited and pressured. This once common snake is an indicator species to the health and quality of our wilder countryside. Surely preserving species and habitats should be a priority. Conservation bodies try to halt species declines but we need far reaching working associations, linking and improving the robustness of habitats and species where possible, not just for the adder but for our own continued future.
Landowners must prove they are real custodians of our wildlife and countryside heritage.[registration_form]