Red-eared Terrapin in Grantham Canal

I had something of a surprise when out walking along the Grantham Canal at the weekend. A friend posted a cracking photograph of a mink on twitter (and now on her blog which you can read here) which was seen along the stretch between Harlaxton and Denton. This is a non-native species and can cause serious damage to the ecosystem through their predation on native species of fish, birds and water vole. However, it is argued that, as these are all food sources for the native otter, the non-native mink is filling a currently vacant ecological niche for a semi-aquatic carnivorous mammal in our waterways. Whilst the grey squirrel competed with the native red in a similar way to the detriment of the reds, there is good evidence to suggest that the re-colonisation of a watercourse by otters will lead to the displacement of the smaller mink and so the native species would win out in the end. Whilst we wait, and hope, for otter to continue their spread through our native watercourses, the mink could be seen as its understudy. They can however cause serious problems in some locations, especially where they prey upon the eggs of sensitive bird species, and eradication programmes are in place in a number of locations to remove them. I have only once seen a mink along the canal, on the stretch by Woolesthorpe some years ago, and was keen to see another.

I was scanning the edge of the canal as we walked along and was taken aback to see a completely different non-native species instead – a red-eared terrapin (Trechemys scripta elegans) basking out of the water on a log! This individual was around 30-40cm which is adult sized. These reptiles, originally from the Americas, were popular pets in the 1980’s and 1990’s following the Teenage Mutant Ninja Turtles on childrens’ TV. They tended to out-grow their confinements and many of the more irresponsible owners simply released them into the wild. They can live for several decades and so this specimen could have been in the canal for a long period of time. The sale of these species does continue however so it could be a more recent arrival.

Red eared terrpin in British canal - Grantham Canal, Lincolnshire, UK

The terrapins feed on aquatic invertebrates and amphibians and so, like the mink, are a cause for concern in British waterways. Whilst the mink is quite able to breed and spread throughout the UK, there is less concern about the terrapins at present – they require around 100 days of >27 degrees or 60 days of >30 degrees for the eggs to successfully hatch and the young to develop which is rarely achieved in a British summer. This puts the terrapin into a different category to the mink – whilst they are not desirable, they are at least naturally controlled by the climate and they should not increase under their own steam. This means that there is not currently a requirement to control them in the wild; rather better controls on the sale of these species should ensure that they do not continue to be a problem once the individuals at large have died out naturally. That said, increased temperatures as a result of climate change could see this whole situation change! A juvenile was spotted Regent’s Canal in London last year and this caused concern that they might have found conditions warm enough to breed in our unusually hot summer.

The individual spotted in Grantham canal may even be the only one present – if no others were released alongside it. There is a record of an European Pond Turtle in the canal from 2006 which may be a misidentification of the same individual I saw, or it could be that this non-native species is also present along the waterway.

Next time you are walking along the canal, keep an eye and you might just spot something unexpected!

Reptiles in Grantham

One of the main aspects of my job as an ecologist is conducting reptile surveys – sadly I’ve never conducted one in or around Grantham but I would love to know what can be found in the local area. If you have seen any reptiles, I would love to know – as would ARG UK who have the Record Pool where you can record your sighting.

The standard way to survey for reptiles is to lay down sheets of refugia – often metal tins, carpet tiles or pieces of roofing felt are used – in suitable reptile habitat, then come back and check to see any reptiles which are either sheltering underneath them or using them to warm up as the sun heats the refugia. This works very well with some species but is less successful at detecting others, such as adders. An alternative way is to approach suitable basking spots, such as log piles, stones or nice south-facing ground early in the day (before it gets too warm and the reptiles move off to forage) and see if you can spot one before it spots you!

Grass snake

The one species I have encountered around Grantham is the grass snake, this is a non-venomous species which is often found associated with water where it hunts amphibians and small fish. One individual I have seen in the Grantham area was along Grantham Canal on the approach to Denton Reservoir and most recently another along a footpath which passes through Croxton Park but I would not be surprised if it were also present within the town of Grantham itself. It is quite an adaptable species and can often be found in gardens, especially if you have a pond. If you do see one, you have no reason to fear it although its main defence mechanism is to secrete an awful smelling substance which you will be able to smell on your hands for a good while after so please don’t touch! They also do a rather disturbing (and in my opinion overacted) job of playing dead, only uncoiling and moving away when they are sure the danger has passed.

The most characteristic feature of a grass snake is the yellow patches on its neck. It could be confused with the adder, but lacks the zig-zag pattern on the back as well as the red eyes. The only other species you may encounter which looks similar is the slow worm but this is a smaller creature (actually a legless lizard rather than a snake) which is a brown/gold colour. This page has some great pointers to help you identify a grass snake.

image

Common lizard

The common lizard is another species which may occur in the Grantham area although I do not know of any confirmed sightings since 1979. This is the only lizard you are likely to encounter in this part of the country and is therefore difficult to mistake for anything else! They are small and often shy creatures whose presence is most often only registered as a rustle in the undergrowth as they scurry out of sight. They are quite a common species in some parts of the country and can certainly be found in north Nottinghamshire around the Sherwood Forest area.

image

Slow worm

The slow worms is actually a legless lizard – this website on Rushcliffe Wildlife suggests they are present in small colonies only a few miles to the north of Grantham. In some parts of the country they are very common with strongholds in the west country where they are regularly encountered in gardens, most often when sheltering under rocks or logs, and are a welcome addition to the pest-control brigade, feeding on small invertebrate prey including small slugs.

image

Adder

The final species which could possibly be encountered in the vicinity of Grantham is the adder – our only poisonous snake. These have been recorded historically but not for almost 40 years now – the last record relates to Salter’s Ford Valley from 1979 according to the data search in this document which I turned up through a quick google search. The habitat typical of adders includes open heathland and moorland as well as rough countryside associated with forest edges. Due to the intensity of agriculture around Grantham, these populations are likely to be isolated and decreases in the availability of habitat in the last 40 years may well have resulted in the population dying out. There is a possibility that they may persist in some of the more isolated locations out to the south of the town towards Stamford.

They will bite if harassed (or trodden on) so do take care if you see anything which you suspect may be an adder. However they will only do so under provocation and in self defense – they will not attack people without good reason! Reports of adders along canals and waterways such as Grantham Canal are almost always a mid-identification of a harmless grass snake which has a great affinity for water where it will swim to hunt. More details on identification can be found here.

image

The other native species – smooth snake and sand lizard – are very specific in their habitat requirements and would not be found in or around Grantham.

I hope this quick guide is useful and don’t forget to record any sightings of reptiles or amphibians in the Grantham area on the Record Pool.

If you’re looking for reptile surveys in and around Grantham and the Midlands in general, check out Landscape Science Consultancy’s website here!

Autumnal Walk along Grantham Canal and Denton Reservoir

It’s been a long time since I’ve updated this blog – everything interesting I’ve seen recently has been far from Grantham, and usually in the dark as bat surveys have filled most of my time! So expect some bat related posts in the near future…

September scene

To get going again; this post is just a few photographs from a walk along Grantham Canal and around Denton Reservoir on a sunny, dew-damp September morning. A little bit of everything! It’s sad to see so many of the wildflowers going over, how can autumn be upon us while we’re still waiting for summer to begin? Still, a few flowers are still hanging on:

Black knapweed (Centaura nigra)

Black knapweed (Centaura nigra) is a favourite with the bees and butterflies and a few are still in flower.

Yarrow (Achillea millefolium)

Yarrow (Achillea millefolium) is a native which you may even have growing in your lawn, or one of the ornamental coloured varieties in the flowerbeds. Look out for the feathery fronds of leaves beneath.

Autumn hawkbit (Leontodon autumnalis)

There are several hawkbit (Leontodon spp.) species – I believe this one is the appropriately named autumn hawkbit. They are in the same family as the dandelion – the daisy or compositae family – but are a much finer, more delicate species.

Ragwort (Senecio vulgaris)

Ever-ebullient ragwort (Senecio jacobaea). There seems to be a fair bit of debate at the moment on whether it really is dangerous for livestock, but it’s another brilliant species for invertebrates. Look out for the yellow-and-black striped caterpillars of the cinnabar moth in July and August.

Creeping thistle (Cirsium vulgare)

Creeping thistle (Cirsium arvense) is another species with a long flowering season.

Rosebay willowherb (Epilobium angustifolium)

Rosebay willowherb (Epilobium angustifolium) flowers later in the season and brightens up the countryside, especially around water. This photo was taken beside Denton Reservoir.

Harebell (Campanula rotundifolia)

Harebell (Campanula rotundifolia) is a species I was not expecting to encounter – this was growing within a sheep-grazed field to the south of Denton. It is a delicate flower often found in more dry, nutrient poor grasslands and heathland, Sherwood forest is a good area to spot them. A welcome addition to the day!

The fields look as though they are on fire from a distance as clouds of dust rise like smoke from the combines. With the crops gone and the stubble remaining, it’s a good chance to look for a few arable plants. There are a number of species which are well adapted to arable conditions and are growing rather rarer these days thanks to the intensification of agriculture. Below are photographs of scentless mayweed (Tripleurospermum inodorum) and common poppy (Papaver rhoeas) – not rare but attractive, I especially love the texture of the poppy flower!

Scentless mayweed (Tripleurospermum inodorum)

Common poppy (Papaver rhoeas)

I spotted a fair few birds within the hedgerows and arable margins, it’s getting to the time of year when large numbers descend on the feast of berries which are ripening. Plenty of blackbirds along with mixed-tit flocks, yellowhammers, chaffinches and an attendant kestrel. This stretch of farmland is a great spot for fieldfares and redwings when then arrive for the winter too.

Yellowhammer

The last few butterflies were still floating and resting in patches of sunlight; red admirals, comma’s and speckled wood all in evidence. Below is a comma (Polygonia c-album) sunning itself on a bunch of ripening blackberries!

Comma butterfly on blackberries

Dragonflies and damsel-flies were spaced out along the edge of the reservoir, the dragonflies jealously guarding their patches. This was my first attempt at a dragonfly in flight, I’m quite pleased with it! I am not 100% confident on the ID but this is certainly a hawker dragonfly, probably a southern hawker (Aeshna affinis) judging by the amount of green on the thorax but please feel free to set me straight if it’s a common!

Southern hawker dragonfly

Cowslip or Oxlip?

Cowslips are a common sight in April and May – brightening up grasslands and motorway verges with their swathes of nodding yellow flower heads. When I first started out in botany, I spent a good while convincing myself that the cowslips were indeed cowslips and not oxlips – Rose’s wildflower key tells you that cowslip is like oxlip but the ‘leaves are more wrinkled and the stem is more gradually tapered to the base’ which requires a certain amount of experience to compare! Luckily the sniff test (cowslip flowers smell like apricots) saw me right!

One simple rule of thumb is location  – true oxlips are a rare ancient woodland species restricted to the part of the country where the counties of Cambridgeshire, Suffolk and Essex meet. Unless you are in a location like this, you are unlikely to be encountering oxlip. But to be on the safe side, here’s a few more pointers!

Cowslip – Primula veris

IMG_9700
Cowslip flowers at Cribbs Meadow – the bright yellow bell-shaped flowers at the top of the stems all nod in a single direction

The flowers of cowslip, like those of oxlip, form a nodding head facing in a single direction. They can be long-stemmed – up to 25cm tall, but are often shorter where the nutrient levels are lower. The flowers are deep yellow with orange flecks in the centre.

IMG_8342.JPG
Cowslip flower at Muston Meadow showing the orange flecks within the flowers – these smell of apricot if you get in close!

You can find up to 30 flowers in a flower head, or sometimes just a few. Remember to take a sniff – the apricot aroma is quite distinctive in a fresh flower!

Oxlip – Primula elatior

IMG_2917.jpg
Oxlip flowering at Hayley Wood – the flowers nod in a single direction and there can be 10-30 in an umbel

Oxlip, as mentioned above, is a rare native found in ancient woodland in a restricted area of the country. If you are encountering the species on a roadside verge or in a meadow in Nottinghamshire, it’s probably not an oxlip. However the species can be bought as a plant, or grown from seed, so it is quite possible it can spring up in unexpected places if it escaped the confines of its sowing!

The oxlip is similar in structure and stature to the cowslip, in growing to ~25cm high and having 10-30 flowers on a head. As with the cowslip, all of the flowers will be nodding on the same side of the stem.

IMG_2865
The oxlip flowers are more open and spreading, lacking the bell-shape of the cowslip. They are generally a paler yellow, and lack the orange flecks inside.

The oxlip flower is less bell-shaped than the cowslip, with more open spreading petals and a lighter, paler yellow. The centres of the flowers lack the orange spots usually found with cowslip.

False oxlip – Primula vulgaris x veris 

IMG_8353
False oxlip along the Grantham Canal – the flowers have the orange flecks of the cowslip but spread wider, reflecting the primrose part-parantage of this hybrid. The flowers face in all directions, rather than nodding in a single aspect.

Just to add to the confusion, there is another species which can be confused with both cowslip and oxlip and this is the false oxlip. The latin name is Primula vulgaris x veris reflecting the fact that a false oxlip is in fact a cross between a primrose and a cowslip, occuring where these two species are found in close proximity. If you find something which you suspect to be an oxlip outside of the correct habitat and geographical area, a false oxlip is your most likely suspect!

The flowers are more open and spreading, a little like an oxlip, but you can see the telltale orange flecks which indicate the cowslip parantage. Rather than nodding in a single direction, as a pure oxlip or cowslip would do, these flowers face in all directions. There is significant variability in the character or these hybrids, with some being closer to the primrose parent and some more strongly representing cowslip.