The Smooth Snake. New Research: Now Venomous but still Harmless

The ‘third’ British snake, the Smooth Snake (Coronella austriaca), is one I have never seen. Of limited distribution, heathland in parts of the south of England, it also occurs widely in continental Europe. Until a few weeks ago the way in which it feeds was thought to be simple. In terms of prey though the preference or availability appears to vary. In Britain small mammals are taken more frequently than lizards; in Italy lizards are the main prey. Young smooth snakes seem to rely heavily on small lizards although they have even been known to eat bluebottles and spiders.

All observers have agreed that once caught in the jaws, the prey is manipulated in to a position where it can be more easily swallowed. During this process coils of the body may help to subdue but not constrict the animal that has been caught. The unfortunate mouse, shrew or lizard is then swallowed alive. Thus the smooth snake was considered to neither venomous nor a constrictor. That is the standard story but in their New Naturalist series book Trevor Beebee and Richard Griffiths raised the point, ‘…so how the snake escapes severe bites from these mammals is not at all clear’. The recent research suggests how that how is achieved.

The authors of the new study, Alessandro Paterna and Grégoire Meier, rely, first, on their own evidence from an anatomical study of the teeth and jaws and, second, on experiments on the closely related species, Coronella girondica, the Southern Smooth Snake, the results of which were published in 1922 in France. In both species they found fangs on the posterior maxilla, the bases of which are enclosed by a sheath. The sheath enables secretion Duvernoy’s gland to be delivered into a wound caused by the fangs. In other words there is every reason to suspect that whole arrangement acts for the conveyance of a noxious secretion into the wound, especially in circumstances where the bite is prolonged and there is time for such a low-pressure system aided by chewing motion of the jaws to work.

There has been endless discussion of whether secretions from Duvernoy’s gland should be called venom and I will not prolong that agony. However, using the term venom for any combination of chemicals used by a predator to the detriment of its prey the question is: does Duvernoy’s gland in this species produce venom? Here one the authors provided useful anecdotal evidence:

…in a field study in the Laga Mountains in the province of Teramo (Abruzzo), one of us (AP) was bitten by an adult male Coronella austriaca while handling the specimen. The bite was prolonged, allowing time to take a photograph while the “mastication” action was still in progress…Following the bite, itching and redness quickly appeared in the affected area. A second photograph, taken 11 minutes after the photo showing the bite, shows redness corresponding to the maxillary arch’s shape, where the holes caused by some anterior maxillary teeth and the pair of posterior fangs

are visible. Over time, in addition to the redness, swelling developed at the site of the small lacerations caused by the teeth, which was also accompanied by itching. The most evident symptoms lasted a few minutes, then gradually subsided in less than an hour. As researchers in both field and controlled environments, we both frequently receive snake bites in different contexts. Nevertheless, this case, although extremely mild, represents the only one to date in which we have personally observed a reaction other than bleeding following a bite of a colubrine snake.

If the bite resulted in irritation to human skin, what about potential prey? Here Marie Félicie Phisalix (née Picot)(1861-1946), who worked in Paris and was one of the leading experts on snake venoms in the first half of the 20th century, provided experimental evidence which I am surprised nobody gathering information on smooth snakes seems to have taken on board earlier.

Marie Physalix
in 1929
Autochrome by
George Chevalier

Marie Phisalix prepared material for injection from whole, dried Duvernoy’s glands. The gland is tiny. She noted in the largest snakes it only weighed 1 mg when dried (equivalent to around 4 mg wet weight). Since it is not known how much secretion would reach a bitten animal, the results show the sort of maximum effect that could be achieved. The findings though were pretty spectacular. An extract from two glands given intravenously to a rabbit put it into a state of torpor for 10 minutes. It then died after 15-20 minutes of respiratory arrest. Six glands-worth killed an adult guinea pig. A green lizard showed transient narcosis after a two-gland dose.

These experiments do suggest the presence of powerful agents in Duvernoy’s gland of smooth snakes. However, I can hear my former and late colleague sitting on my shoulder warning that some of the effects could be due to the presence of extraneous substances like bacterial toxins from the mouth and I do hope that the recent work is being followed up to see what biologically active substances are present in the Dubernoy’s gland of smooth snakes. Secretions from the gland of other rear-fanged species have been studied, for example by Robert Hill and Stephen Mackessy in 2000, and a comparison with such findings is now essential.

Smooth Snake
The colour plate from Malcolm Smith's The British Amphibians and Reptiles published in 1951
in the Collins New Naturalist Series
Photograph by Walter Sydney Pitt (1900-1983)

It would seem though that the evidence is highly suggestive of a rear-fanged, low pressure venom delivery system. Observations on C. austriaca collected by Malcolm Smith for his New Naturalist series book published in 1951 indicate that some items of prey, small lizards for example are caught and swallowed quickly. However, larger prey like small mammals with the capacity to bite back may be held onto for longer, allowing noxious agents from Duvernoy’s gland to seep into the wound, enter the bloodstream and render the mouse, vole or shrew quiescent.

Thus it seems we should now consider the Smooth Snake to be Britain’s second venomous snake with the proviso that the venom is so weak that even if a human being were to be bitten the only effect would be slight and temporary inflammation in the area surrounding the puncture marks. Perhaps we should just say Britain still has two snakes that are entirely harmless to the human population.

Paterna A, Meier G. 2026. Reclassification of the smooth snake. Analysis of the rear fangs, venom system, and the cephalic anatomy of Coronella austriaca (Serpentes: Colubridae). Zootaxa 5873 (1): 145–160. https://doi.org/10.11646/zootaxa.5873.1.8

Phisalix M. 1922 .Animaux Venimeux et Venins. Vol. 2. Paris: Masson et Cie,

Beebee TJC, Griffiths RA. 2000. Amphibians and Reptiles. A Natural History of the British Herpetofauna. London: HarperCollins.

Smith M. 1951. The British Amphibians and Reptiles. London: Collins.

Hill RE, Mackessy SP, 2000. Characterization of venom (Duvernoy’s secretion) from twelve species of colubrid snakes and partial sequence of four venom proteins. Toxicon 38,1663-1687 https://doi.org/10.1016/S0041-0101(00)00091-X

Purple-throated Woodstar. Colombia - November 2025

This female Purple-throated Woodstar (Philodice mitchellii) was gathering nectar from the flowers in the garden of the Hotel Kumanday on the edge of the village of La Florida, a popular place for those visiting the Otún Quimbaya reserve on the western side of the Cordillera Central of Colombia. The village is at 1,670 metres (5,480 ft).

The bird occurs from 700-2,200 metres along the chain of the Andrews from Colombia into Ecuador. There is what appears to be an isolated population in southern Panama. 

Barely 3 inches long with their flight resembling a bee, this one spent a great deal of time keeping its energy supply up - for all that flying and hovering. Their demand for sugar and they way their body bodies handle that sugar to keep up with demand can really be appreciated by seeing and watching hummingbirds in the wild.

Western Bluebird: a colour plate from 1937

In the days when colour printing was extremely expensive, the Avicultural Society had special appeals for funds to support the appearance in Avicultural Magazine of the occasional colour plate. A well-known bird artist was then commissioned. Although the whole run of the Society’s magazines can be found online, the plates rarely see the light of day. Therefore I decided to show one, now and again, on this site. This is the 24th in the series.

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The plate is by Roland Green (1890-1972) a well-known bird and mammal artist who lived in Norfolk. He was the son of a taxidermist. He illustrated a number of books, including one of his own.

The author of the accompanying text was the well-known aviculturist and very wealthy, Alfred Ezra (1872-1955). He understood that the bird had never been imported into Britain before those brought by Jean Delacour. A pair bred in one of Ezra’s aviaries.

The Western Bluebird (Sialia mexicana) is from western North America and Mexico.

Avicultural Magazine September 1937

A Comma in the garden

Alloway, Ayrshire, Scotland. 1 August 2026

It is difficult to imagine the look on a 1950s lepidopterist’s face had she or he been told a Comma butterfly had been spotted in Ayrshire. Even in England the butterfly then had a limited distribution in the south, although it was spreading back to earlier haunts as the 1951 edition of that classic The Observer’s Book of British Butterflies explained:

Up to about 1924 this butterfly had been gradually disappearing from all its old localities, and was more or less confined to Herefordshire, Worcestershire, and Monmouthshire. Since then there has been a remarkable increase in its numbers, and it has been reported from the southern, western, and midland counties and even the London district*.

The Butterfly Conservation website takes up the story:

…the most remarkable feature of the Comma has been its severe decline in the twentieth century and subsequent comeback. It has spread northwards through England and is now widespread in south-east and central Scotland and its range is expanding.

Over the past years there have been a number of reports of Commas in Ayrshire and this one is the second we have seen in the garden.

The Comma, Polygonia c-album, has an unusual specific name in that it it hyphenated. However, that was the one given to it by Linnaeus himself and the Comma was a species with which he would have been familiar since it occurs throughout Europe and into western Asia.

Informative studies have been made on the genetics of the food preferences of the Comma caterpillar. At present in Britain the preferred food plant is common nettle with hops, elms, currants and willows following on behind. The great decline in the 19th and early 20th centuries was thought to have been caused by a major reduction in the cultivation of hops. If that decline was responsible then the shift to nettles and subsequent recovery could have been an event as significant as industrial melanism and its reversal in the Peppered Moth.

The underside shows how well the butterfly is camouflaged when its wings are closed
The white marking is in the shape of a comma; hence the name

*The Oxford comma (no pun intended) was alive and well in this Observer’s Book. Described as the compiler of the book William John Stokoe had drawn the information from The Butterflies of the British Isles by Richard South (also published by Frederick Warne). The first edition of The Observer's Book of British Butterflies book appeared in 1938 when Stokoe was 74; it ran for many editions, some long after the compiler’s death. William John Stokoe was born on 30 July 1864, the son of a railway signalman. In the 1921 Census and the 1939 Register he was living in Finchley with his wife. In 1921 he was art manager for Frederck Warne and in 1939 ‘Book Publisher’s Editor’. Stokoe died on 16 March 1947. His name continued to be associated the the various Observer’s Books he had compiled.

John Anderson’s Newt on the Road from Mandalay

The first of what are now known as crocodile newts to be described in the scientific literature was Tylotriton verrucosus from Yunnan Province in China. A welter of new species of Tylotriton has been described in the past few decades—38 at the latest count—but how many would pass as proper ‘biological species’ is open to question. Newts from south-western China have been studied because tectonic shifts during the Pleistocene have resulted in mountain ranges and deep river gorges within a relatively small area, leaving plenty of opportunities for the isolation or partial isolation of breeding populations and the emergence of new geographical variants and new species.

A considerable amount of knowledge has accumulated on the natural history of T. verrucosus which at present goes under the common names in English of Western Himalayan Crocodile Newt or Longchuan Crocodile Newt. Indeed some studies have been made at or near the sites of its discovery. However, little attention has been paid to the circumstances under which John Anderson saw, collected, described and named the species. Anderson found the newt while medical officer and naturalist to the British mission into Yunnan from Burma in 1868. The party led by Captain Sladen travelled by steamboat from Mandalay to Bhamo and then by land. Anderson published his account of the new species in Proceedings of the Zoological Society of London in 1871. The bland description by Anderson does not cover the tribulations of the mission which have been described recently by David Leffman in his book A Murder in Yunnan and in the account by Anderson himself in 1876.

from Anderson 1871

Particularly noticeable in these newts are the large skin tubercles which form a line each side of the body. Underlying each glandular tubercle is a blunt rib and it is presumed that the ribs help press toxic secretion from the glands if the newt is compressed by the grasp or bite of a predator

Anderson wrote of his newt:

Hab[itiat]. Nantin, Momien, and Hotha valleys, Western Yunan, China. 

I first met with this remarkable Newt in the flooded rice-fields about the little Chinese town of Nantin, where, however, it was not very common. In the more elevated and subtemperate valley of Momien, at about a height of nearly 5000 feet above the sea, and in the high sequestered valley of Hotha (5000 feet) it was far from uncommon.

I have marked these places on a map from Anderson’s book. They are all along the Taping or Daying River or one of its tributaries. The Taping flows from the east to join the Irrawaddy near Bhamo in Burma (Myanmar). Later reports also show T. verrucosus occurs in that part of northern Burma. 

A map from Anderson's 1876 account of the two missions to Yunnan
Th red dots show the sites Tylotriton verrucosus was seen
Yunnan-Fu is now Kunming. Momien is Tengchong. 

The 1868 Mission was fraught with uncertainty and danger. Anderson described the following incident in one of the areas the newt was found. The background to this particular episode is that a Muslim Revolt was in full swing in Yunnan against the Qing Dynasty and the Panthay rebels held towns and villages along the route the mission was taking. Near one of the places the newt was found the party rested a for a while at hot springs:

After enjoying our halt, which had been made with the full approval of the Panthay officers and the Hotha chief, we started to overtake the cavalcade, which had marched forward. Just as we rejoined the rear-guard, four shots were fired in front, but as the road only admitted of single file, and lay along a thickly wooded hillside, marked by the ruins of many villages, no one could advance to reconnoitre. Word was presently passed down that the mules had been attacked and two Panthay officers wounded but on proceeding onwards, we discovered that the affair was more serious, and that the two officers and another man had been killed. We soon came up to the bodies of the officers wrapped in their large turbans and tied to bamboos, ready to be carried back to Nantin. The poor fellows bad both been great favourites with their comrades and the governor of Momien; and a sad group surrounded the bodies, including their female relatives, who had ridden out from Nantin only to lament their murder, for so it was. As they were riding at the head of the mules, at a corner in the narrow path, a lurking body of Chinese rushed out from the trees, shot down the first, and the second, hurrying to the rescue, was shot through the leg and cut down with a dah. Eight mules had their loads thrown off and looted, and were then driven up the hills. A little further on, the scene of the disaster was marked by the ransacked packages lying on the roadside, and among them two boxes containing my clothes and note-books. One of these had escaped unopened, and was left in charge of a Panthay officer who promised to see it brought on. At the head of the valley a halt was called, to enable all the Panthays to come up, as a second ambuscade was suspected in a thickly wooded hollow in the steep hillside above.

Newts and other specimens of the local fauna were not the only things Anderson brought back from Yunnan. The British Museum has a Shan dao, a knife made of metal, wood and string, from Hotha presented by Anderson. It is I think of the same type used in the above account to kill the Panthay officer.

The dao presented by John Anderson to the British Museum

Newting in Yunnan in 1868 was not a gentle pursuit for a spring afternoon.

from Hernandez 2016

Anderson J. 1871. Description of a new genus of newts from Western Yunnan. Proceedings of the Zoological Society of London 1871, 423-425.

Hernandez A. 2016. Crocodile Newts : The primitive Salamandridae of Asia (Genera Echinotriton and Tylototriton). Frankfurt: Edition Chimaira.

Lord Derby’s Woolly Opossum. Colombia, November 2025

I find the marsupials of the Americas fascinating. The opossums with their long rat-like tails cannot compete in the cuteness stakes with the possums of Australia. Although I have been to the USA many times (to sit for hours in a darkened lecture theatre) and the countries in Central and South America, until Colombia in November last year I had never seen an American marsupial. Then along came three species.

A delight of a mammal-watching trip* as opposed to a birding one is the greater emphasis on night spotting. Birds, reptiles, amphibians and invertebrates are seen as well of course. On our first night walking along the road through the Otún Quimbaya Sanctuary on the western slope of the Cordillera Central we saw this Derby’s Woolly Opossum (Caluromys derbianus) by the light of the spotlamp. It is a terrible photograph since I had the camera set for a bird before darkness fell and pressed the shutter release anyway in the hope of getting something on the camera’s sensor.

Derby’s Woolly Opossum occurs from Mexico through the countries of Central America and then as far south as Ecuador. The alternative name of Central American Woolly Opossum as used in the IUCN Red List therefore seems misleading. In Colombia we were seeing the animal at the eastern edge of its range since it is confined by the Cordillera Central to the Cauca Valley. The river Otún flows westward into the Cauca.

The species was named for the well-known politician and zoologist the13th Earl of Derby (1775 – 1851) who had a large menagerie and museum at Knowsley Hall near Liverpool. Seeing his eponymous opossum in South America or his Derbyan Parakeet in the wilds of Sichuan in China does feel incongruous—and very unLiverpool.

On the other side of the Cordillera in the Magdalena Valley we saw a Brown-eared Woolly Opossum (Caluromys lanatus) briefly before it disappeared behind a tree trunk. 

Another species at Otún Quimbaya was the Common Opossum (Didelphis marsupialis). It was around the lodge and restaurant at the end of the road. We saw the same species on the rafters of our accommodation at Hato La Aurora in the Llanos, the wetlands of north-eastern Colombia. 

Opossums often produce more offspring than mammary glands. Therefore any that do not find a teat in the female’s pouch die. As in marsupials generally the young remain attached to the teat for virtually their entire development.

I did not know opossums were popular items in the human diets of the Americas, from the USA southwards. I cannot say I fancy the idea.

*Naturetrek’s Colombia’s Endemic Mammals

Edward Bosc Sladen’s eponymous animals from the 1868 mission from Burma to Yunnan

Sir Edward Bosc Sladen spent much of his career as a soldier/colonial administrator/diplomat in Burma. He was the natural choice to lead the mission to Yunnan in 1868 which was sent to explore the possibility of establishing a trade route between British India, Burma and China and on which John Anderson was the medical officer and naturalist. At the time of the mission to Yunnan Sladen was a Captain in the (British) Indian Army and In 1866 he had been appointed agent of the chief commissioner in Mandalay. In that year he narrowly escaped insurgents who had murdered three of the royal princes. During the subsequent disturbances Sladen gathered nearly all the Europeans and ‘other christians’ on board a steamboat and and evacuated them safely to Rangoon. After his return to Mandalay he persuaded the King of Burma, by then only in control of ‘upper’ Burma, not to execute three young princes. Only two survived, the third having been beheaded before news of the reprieve. After that he obtained the King’s assent to a new treaty covering commercial activity and extradition. It was against this background of hard and soft power that Sladen was chosen to lead the mission to China in 1868 described in David Leffman’s A Murder in Yunnan.

Sladen was born in Madras in 1827* to Dr Ramsey Sladen, Physician General of Madras in the East India Company, and his second wife, Emma Bosc. After Oswestry School he became a cadet of the East India Company in 1849 and on returning to India was appointed subaltern in the 1st Madras Fusiliers, a European regiment in the Company’s army. He served in the 2nd Burmese War. In 1853 he was appointed an assistant commissioner in Tenasserim. He was severely wounded during operations against insurgents in 1856-1857. In 1858 it was back to regimental duties. His regiment was heavily involved in the relief of Lucknow and further operations against the ‘mutineers’ in Oudh. Once back in Madras, Sladen reverted to the work of a district officer in Burma. The Staff Corps formed in the three Indian armies in 1861 enabled eligible officers to take up civil and political placements. When the 1st Madras Fusiliers became a royal regiment (i.e. a British Army regiment in India) Sladen became a member of the Indian Staff Corps but in 1878 still appeared in the Army List as in the Madras Staff Corps.

Captain Sladen of the Yunnan mission was promoted to major in 1869 and lieutenant colonel (without the hyphen in the modern style) in 1875. From 1876 until 1885 he was commissioner for the Arakan division. Then he was chief political officer to the force sent to depose Hing Thibaw in ‘upper’ Burma—the third Burma War. On 28 December Sladen arrived with the British troops sent to Mandalay. He entered the royal palace and took Thibaw’s surrender. The whole of Burma then became part of the Raj. Sladen was greatly praised by the viceroy for his courage and knowledge of the people of Burma. In 1886 Sladen was knighted and retired to England in 1887.

Sladen married Sophia Catherine Harrison in 1861; she died in 1865; they had a son and a daughter). Fifteen years later he married Kate Carew of Carpenders Park, Hertfordshire, in London; they had a son.

Sladen died in London on 4 January 1890, aged 63. He was living at 30 Lowndes Square, Chelsea. Newspaper reports provided the level of detail required by Victorian readers. 

We also have to announce the death of Colonel Sir Edward Bosc Sladen, which took place of pneumonia, after a very short illness, in Lowndes square, on Saturday night. He and Lady Sladen were present at the Marchioness of Salisbury's ball on the 20th ult., but on returning to town next day he found himself attacked with the influenza epidemic which is now so prevalent, and which culminated in the disease to which he succumbed so quickly.

The press, following the money, also reported:

…The late Sir Edward was in receipt of a good service pension for distinguished and meritorious services; had the Indian Mutiny medal with clasp for Lucknow, and the Burmah medal with clasp for Pegu…

John Anderson who served as both medical officer and naturalist to the 1868 mission clearly thought highly of Sladen. H e named a number of species for Sladen as well as suggesting his name to those who he asked to work on the insects and fish collected during the trip. Those names have of course been subject to many later revisions of taxonomy and have either been entirely subsumed as synonyms into other species or retained as subspecies.

THE RAT

Anderson’s Mus sladeni, latter Rattus sladeni is a species I have written about previously. The original—but not necessarily those rats from other parts of Asia that came to be known as Sladen’s Rats—is now lumped in Rattus tanezumi, the Asian House Rat.

THE SQUIRREL

A Sladen eponym missing from the Eponym Dictionary of Mammals is Sciurus sladeni. This beautiful squirrel is now lumped into Pallas's squirrel (Callosciurus erythraeus) which has major geographical differences in coloration. Some schemes retain the subspecies C. e. sladeni.

THE PHEASANT

Also missing from the books on avian eponyms is the pheasant Phasianus sladeni, now regsrded as a subspecies from northern Burma of the Common Pheasant: Phasianus colchicus sladeni.

THE FISH

Anderson appears to have handed over fish collected during the mission to Francis Talbot Day (1829-1889) a fellow medical man who became Inspector General for Fisheries in India. He named a freshwater fish for Sladen but got the name wrong: Salmostoma sladoni. Interpretation of hand-written labels after immersion in spirit is not easy.

THE TIGER MOTH

Frederic Moore (1830–1907) who worked at the East India Company’s museum in London sorted the insects. He named a tiger moth for Sladen: Syntomis sladeni. It survives as a full species, Amata sladeni.

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I thought that is all I had to write about Sladen and his eponymous animals. However, I now find that his son had a major role in a great public health problem of the 19th and 20th centuries. Edward Sydney St Barbe Sladen was medical scientist, soldier and zoologist, I can argue that I would not be sitting where I am today had he and his colleagues not tackled a zoonosis that still costs the UK millions of pounds every year to combat.

The colour plates are from: Anderson J. 1878. Comprising an Account of the Zoological Results of the Two Expeditions to Western Yunnan in 1868 and 1975 and a Monograph of the Two Cetacean Genera, Platanista and Orcella. Second Volume - Plates. London: Bernard Quaritch.