I smell a rat

16th July, World Snake Day

The region of southern Ontario where I was lucky enough to be able to stay for a couple of weeks in the first half of July holds an important yet threatened population of the Gray Ratsnake, Pantherophis spiloides. While participating in the memorable BIOSPHERE Youth Environmental Leadership Expedition at the Queen’s University Biological Station (QUBS) on the shores of Lake Opinicon, the enthusiastic program leader Dr. Shelley Ball interrupted our dinner one evening with a Gray Ratsnake she had just hand-caught. Perhaps one of the few things I will stop dinner for!

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Gray Ratsnake being held by Shelley

Gray Ratsnakes are one of Canada’s largest snakes. They are the largest in terms of length, with adult able to reach over six feet from head to tail, but are pipped by Bullsnakes with regard to mass.

During the expedition at QUBS, we were treated to a short presentation by Matt and Meg who are working on how to prevent the decline of this sizeable snake. One of the leading causes of fatalities in this species is road collisions. The dark colouration of the ratsnakes means that they are often mistaken for the shadows of overhead branches on roads, and are therefore not noticed by motorists. Even when they are recognised as snakes drivers have a hard time avoiding them, as due to their length they can easily stretch across the entire width of the road.

On account of this, Matt and Meg are working on avoiding these snake RTAs by reducing the incidences of snakes crossing the road. They are helping to develop snake-proof fences which aim to guide the snakes to specially-built culverts which they can use to get to the other side of the road without risking being hit. Gray Ratsnakes are semi-arboreal and spend lots of their time in trees, so are adept climbers. The fences to be implemented, therefore, need to be resistant to climbing by these agile snakes. Creating fences that not even ratsnakes can ascend also prevents a wide variety of other wildlife such as turtles from being hit and allows them to utilise the culverts as well.

Gray Ratsnakes are remarkably docile and are rarely aggressive when handheld. When threatened they do possess the abilility to release the contents of the cloaca, musking the assailant with a foul smell. However, the related Northern Water Snake behaves in this manner with far greater regularity. It, like the Gray Ratsnake, is non-venomous, so has to make itself as unappealing to predators as possible, by releasing both musk and excrement. Despite the lack of venom, the bites are still painful and the saliva of the Northern Water Snake has an anticoagulant which causes the bite to bleed more freely. However, although it might sound threatening, the water snake is another fascinating reptile.

I had the good fortune of glimpsing a Northern Water Snake on one occasion at QUBS as it swam past the boathouse. As its name suggests, it is a very strong swimmer. It will take sleeping fish at night in shallow water and during the day it will hunt other prey such as crayfish and amphibians among vegetation at the water’s edge.

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Northern Water Snake snaking through the water at the QUBS boathouse

To finish off this post for World Snake Day, I’ll mention the third species of snake we encountered on our expedition at QUBS, which was also the most numerous. The Common Garter Snake is, as its name suggests, frequent, but also fairly skittish. As a result, they are difficult reptiles to photograph. However, nearing the end of the expedition we disturbed one from a pile of dead leaves near the library. It retreated to a stone wall, from which it poked its head out to survey the scene, giving a rare opportunity to photograph this species.

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A curious Common Garter Snake.

The Common Garter Snake, like all but one snake in Ontario, is another non-venomous species. Snakes are often misrepresented as being solely dangerous creatures. However, less than a fifth of the world’s snake species are considered a threat to human health, with very few venomous snakes being found in the more populated temperature regions of the world. Instead of being feared, snakes should be more appreciated for their incredible diversity and fascinating range of habits.

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Sussex Rarities – Hairstreaks & Clubtails

This morning, having heard some exciting news on the website of the Sussex branch of Butterfly Conservation, I found myself in Ditchling Common Country Park, scanning bracken after bracken with my binoculars. I was looking for a Black Hairstreak or two. The windy and overcast conditions were not conducive to my hopes of sightings along the lines of the day-count of 98 that was made earlier in the month!

These numbers are quite extraordinary considering the fact that this species was only confirmed to be found in Sussex just over a week ago. Following a few battered individuals found at the same site last year, a survey has been undertaken to determine the presence of this colony. Its appearance here is particularly notable as this site is far from the existing distribution of this species in the UK. It is thought to be confined to a band of clay soil in the Midlands, mainly Cambs, Northants and Oxon.

The closest Black Hairstreaks have previously come to Sussex is Surrey, where they were introduced in the middle of the 20th century. However, the habitat at the introduction site was destroyed and the species disappeared there. The species is not known for their long distance movements or dispersal at all, in fact patches of identical habitat to where they are found elsewhere on the same site often go uninhabited due to the reluctance of the butterfly to travel long distances. Therefore it is thought that this colony is also an introduction similar to the Surrey one, although despite it only being discovered very recently it is likely that the species first appeared in the 1990s – this is because the expanse of the population at Ditchling Common suggests that it has been expanding for quite a while. It’s so slow that the rate of expansion, even of a healthy population, is estimated to be only about a kilometre per decade!

Now, back to this morning. The foodplant of the Black Hairstreak is Blackthorn, and it was in abundance at the country park. This was especially true at a corridor that extends from the fish pond south-west to the Folders Lane East. This was where we focused our searching, which turned out eventually to be the right idea. At 10.30 the sunshine finally made a prolonged appearance and the wind died down slightly. This appeared to trigger the daily emergence of the hairstreaks to warm up on the bracken. The first one we found was perched at quite a gradient on one of the fronds, perfectly angled towards the sun. After a few minutes of sitting very still, it switched sides rather in the fashion of a sunbather aiming for an even tan. As it had not yet gained enough thermal energy it was being quite ‘co-operative’, allowing for great views. This sighting was repeated with up to three other Black Hairstreaks, a very satisfying way to see a new butterfly species for me: not a common occurrence!

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Although the sexes are hard to differentiate on physical appearance, it is likely that those we found were females. The males will emerge earlier, in order to have established a territory prior to the emergence of the females. They will fiercely defend their territory, which is usually centred around an oak known as the ‘master oak’, and approaching the end of the flight period this activity will render them quite battered and damaged. It is likely that this species is past its peak already this year. The species’ very short flight period is one reason why this colony may have remained undiscovered for such a long period of time. Years where the population is dramatically increased compared to previous and following years are also characteristic of this species. It is likely that this year is one of these ‘boom years’ which is what may have lead to this year being the one in which this colony was finally discovered. So if you haven’t yet had a chance to visit this true Sussex rarity, I would recommend that you do so sooner rather than later. Their short adult stage will be over before the end of June, and in future years there probably won’t be as many as there have been this year.

Black Hairstreaks are not the only entomological rarity I’ve had the good luck to see in Sussex this month. At the beginning of the month I took a walk along a small stretch of the River Rother, near Fittleworth in West Sussex. Having been advised about their presence there by Amy Robjohns and Olly Frampton, I was on the lookout for Common Clubtails, a species that isn’t actually as common in the UK as its name suggests. On the British Dragonfly Society website it is described as “extremely local”, only being found on a few rivers in Wales and southern and central England.

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However, its scarcity on a national basis was certainly not evident along this tranquil, luscious river in the mid-morning sun. Along only a few hundred metres of the river we managed to find at least 10 either hunting along the river or perched on bankside vegetation and overhanging willows. The vast majority were males which were patrolling their recently acquired territories while many females would be seeking protection in the nearby woodlands away from the water. They will soon return to mate and lay a new batch of eggs, which will complete their immature stages in the silty riverbed within 3-5 years.

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