It’s very nearly Halloween – what better time to introduce you to the bats which haunt Grantham Canal when darkness falls…
I spent several nights this September cycling along Grantham Canal with an EM3 bat detector connected to a GPS unit, recording the bats in flight between the A1 to the east and Hickling Basin to the west. Bats use echolocation to navigate and hunt and the bat detector converts this ultrasonic sound into something we can hear. The sound emitted by the detector tells you when a bat is there, often which species it is and sometimes even what it is doing.
You might imagine that this is quite a sinister place to be, surrounded by bats on a moonlit night, but there really is nothing to be afraid of! As the detector tapped and pattered away to announce their, I could see bats flying before me in the darkness. But even though I was cycling towards them, they elegantly avoided me every time, never making contact and certainly never tangling in my hair. This is one of the most enduring myths about bats but their fantastic echolocation abilities mean that they can ‘see’ and avoid obstacles on even the darkest of nights.
I recorded at least five species in September, some calls with ‘buzzes’ indicating foraging and some with ‘song flight’ where male soprano pipistrelles emit lower frequency social calls to attract mates. These are just on the edge of human hearing and can be heard without a detector – you may have heard the very high frequency chirrups if you walk outside at dusk in the autumn.
Common Pipistrelle
The Common Pipistrelle is the smallest and the commonest UK species
The common pipistrelle is our most abundant species in the UK, and was encountered throughout the route of the canal, particularly where there are more trees as this species specialises in hunting along ‘edge’ habitat which is typically along hedges, tree lines and other landscape features.
The orange bat symbols in this map indicate the locations where common pipistrelle bats were identified. The A1 which dissects the canal is at the far eastern end with Hickling Basin marking the western extent
Soprano Pipistrelle
The soprano pipistrelle is physically similar to the common pipistrelle but has differences in morphology such as wing veination and face colouring with the much darker face of the common pipistrelle earning it’s other name of bandit pipistrelle
The soprano pipistrelle is very similar morphologically and was not even identified as a separate species until 1992. Now they can be told apart confidently in their hand, and with fair reliability acoustically as the soprano pipistrelle calls at 55 kHz compared with the common pipipstrelle at 45 kHz. In England, the soprano pipistrelle is often found associated with water and so it was no surprise to find them along the canal. An interesting observation however is that there appears to be much more activity to the east, near to larger water bodies. Denton Reservoir lies just beside the canal towards the eastern end and is likely to be an important foraging resource for this species.
The blue bat symbols in this map indicate the locations where soprano pipistrelle bats were identified. The A1 which dissects the canal is at the far eastern end with Hickling Basin marking the western extent
The vast majority of the recordings related to these two pipistrelle species – the other bat species were found at much lower frequencies.
The yellow bat symbols in this map indicate the locations where Natterer’s bats were identified; black represents whiskered/Brandts; purple represents brown long-eared; and green represents noctule. The A1 which dissects the canal is at the far eastern end with Hickling Basin marking the western extent
Noctule
The noctule bat is our largest species and tends to fly high and early, often the first bat to appear around sunset and can be seen in the skies as the swifts are still on the wing. Only one noctule was heard during the transects, between Denton and Woolesthorpe and picked up again near Muston. This bat is large and the sky was light meaning I could watch it flying my way, foraging as it flew to the west. This is a widespread species which favours roosting in trees, but numbers are generally lower than the pipistrelles.
Noctule bat – the largest UK species
Brown long-eared bat
Brown long-eared bat is one of our quietest but most charismatic bats. Their large ears make them quite charming to behold, and they are frequently found roosting in barns and other buildings. I only picked up a single instance of this bat, but their very quiet echolocation means they are generally under-recorded.
The brown long-eared bat is named for quite obvious reasons!
Myotis bats
The myotis bats are considered to be some of the most difficult to identify from sound alone. Daubenton’s bats are the myotis species most frequently associated with water as they specialise in flying low over still waters and taking insects on the wing or from the water’s surface. Natterer’s bat is another myotis species and some of the calls recorded along the canal in September are characteristic of this species. Whiskered and Brandt’s bats are the other two myotis species which are likely to be present in this part of the country. These two bats are very similar to one another and are difficult to separate even in the hand. Some of the calls have the characteristics of one (or both) of these two species. Whilst these species are not commonly associated with aquatic habitats, the canal also boasts hedgerows, copses and grass bank margins which provide great terrestrial habitat as well.
A Daubenton’s bat – the myotis species most frequently associated with water. The myotis bats are larger than the pipistrelles but not as big as the noctule.
I encountered a whole host of other species whilst cycling along in the afterglow of sunset including barn owls, tawny owls, hares fleeing down the towpath and badgers snuffling in the hedgerows. The canal is stunning in the daytime but at night it comes alive with a whole host of new species – a walk around sunset might reveal creatures which you would not normally be privileged enough to watch.
If you are looking to commission bat surveys in the Midlands area, check out Landscape Science Consultancy’s website here!
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.
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!
For something a little bit different, I thought I would share a walk which is one of my favourites in the area. It starts from the village of Harlaxton to the west of Grantham and takes you out across farmland, through woods, around Denton Reservoir, follows the canal for a while as well as a taking in stretch of the ancient track – the Viking Way. Best of all, the mid-way point of the walk has a choice of two different pubs where you can stop for lunch!
The walk is 9.3 miles in total and can be shortened in a few places if you consult an OS map. This includes cutting up the Viking Way to avoid the village of Woolesthorpe (and both of its pubs!) and starting in Denton rather than Harlaxton.
The numbers on the instructions relate to the map. I have also put in italics a few points of interest along the way.
Harlaxton to Woolesthorpe Walk Map
I hope you enjoy this walk and that all the instructions are clear – let me know if you try the route out and anything interesting you see along the way!
Point 1
Start the walk in Harlaxton village – there is a layby where you can park opposite the medieval monument and phone box which are just beside the village shop. To reach the starting point from the A607, turn left into the main village (if you are coming from Grantham) and follow the road round until you find this location.
To begin the walk, head back up towards the A607 on the High Street.
As you pass the shop, you can see a field on the left-hand side which is an old orchard often grazed by a diminutive pony. There are often interesting wildflowers such as greater celendine to be seen along this edge in the summer months, as well as spring flowers such as forget-me-not earlier in the year.
Point 2
When you reach the A607, turn left and walk west for a few minutes until you reach the see a wide layby on the opposite side of the road. At the nearest end of this, you will see a metal gate and a footpath sign pointing you north along a track signed Peashill Lane. Take this track, being careful to close the gate properly behind you, continue past a farmstead and follow a rough track down a gentle slope.
There are a number of old ash trees lining this track as well as interesting wildflowers with the purple flowers of common vetch and black knapweed on the verge mingling with more arable weeds such as pineapple mayweed and field poppies on the edge of the crops.
When the footpath forks to the left or the right, take the right to do a slight kink but continue down towards the canal in the same direction as previously.
Point 3
On reaching the canal, turn left through a gate and head diagonally across to the opposite corner of the field where you will find a gate allowing you onto a wooden footbridge over a ditch.
This field is a great spot to see fieldfares and redwings which migrate into the country in the winter time and can be seen from around October onwards. They forage in the open countryside and will quickly strip the remaining red and purple berries from hawthorn and blackthorn.
Point 4
Having passed over the ditch, continue straight ahead to the right of the hedgerow before you until you pass over a stream and up a set of steps to reach Denton Reservoir.
Denton Reservoir is one of the best spots for waterfowl in the area – many species such as mallards, great crested grebes, coots and moorhens can be seen all year round but are joined by large numbers of tufted ducks and pochard during the winter. You might also spot cormorants and herons on this waterbody.
The reservoir is favoured by anglers and you might be lucky enough to spot species including pike and perch if you keep an eye on the water as you walk around.
At night, this is a great spot for bats with Daubenton’s and soprano pipistrelle foraging across the water. They can be best seen during a visit around half an hour after sunset on any warm evening between May and September. The much larger noctule bat flies high over the hedgerows and field edges which run around the perimeter of the reservoir, hunting insects on high rather than taking those which arise from the water.
Walk to the right around the edge of the reservoir, taking care as there are no rails or fences, until you reach a path which drops down to your right in a gentle slope to bring you to a little brook which leaves the reservoir here.
Point 5
Take this path down and then follow the brook away from the reservoir until you reach a point where the path turns left or right. Take the path to the left. Quite quickly, when the woods end on your right hand side, turn right along the boundary between the trees and the field.
Walk along the woodland edge for the length of a field, then pass into the next. Here, cross the field diagonally along a well trodden path until you reach a small carpark area and a bridge which passes over Grantham Canal.
Point 6
Cross over this bridge and then turn left to follow the tow-path of Grantham Canal as it winds through the landscape.
Grantham Canal
The canal is an excellent way to ‘reveal’ the landscape it passes through. It was built to be as flat as possible, to minimise the need for locks, cuttings or embankments. With this in mind, the meandering route and wide loops which the canal takes reveal quite subtle undulations in the landscape, as well as more prominent landforms. As you leave the bridge, you will notice a wide loop which the canal takes around a field and, looking back, you notice the way that this farmland rises up.
You will pass under 3 more bridges as you proceed. The first is the road bridge for Casthorpe Road which links Denton and Sedgebrook. The second is an old canal bridge similar to the first which you can take left to follow the Viking Way up Brewers Grave – this route will take you all the way to Oakham to the left or Hull to the right. The third is a small footbridge which takes a footpath up to the road between Denton and Woolesthorpe.
The hedgerows which flank the towpath to the right provide a feast of blackberries and sloes in the autumn. There are also hawthorn berries which are also edible although not entirely pleasant in my experience!
If you look to the water, you can often spot shoals of juvenile fish including roach and dace as well as their larger parents further out into the channel.
Dragonflies and damselflies are to be found in abundance along here in the summer right through to September. The dragonflies are usually much more substantial, and hold their wings out flat when at rest, as though they were soaking up the sun. Damselflies, often an iridescent blue, hold their wings together, as though they were making themselves as unobtrusive as possible.
Walk along the canal until you pass the locks and reach another bridge, just before the pub.
Point 7
Cross the bridge just before the Rutland Arms (or the Dirty Duck depending on your preference).
The pub does good standard pub food and offers a range of ales and other drinks for refreshment – a stop on one of their canal-side picnic benches is often a welcome rest at this point. This pub can get very busy, especially on nice days, so bear in mind that there is also another pub at Point 8.
Then follow the track away from the canal up to the road where you will turn left towards the main village of Woolesthorpe. There is a pavement along this section. Cross and continue in the same direction when you reach a crossroads and turn left when you reach Worthington Lane.
Point 8
Walk up Worthington Lane until you come to a second pub called The Chequers.
The Chequers offers a slightly more refined fare than the Rutland Arms – think ciabatta rather than sandwich! They also do a good range of drinks and there is a large beer garden at the back which is always a pleasant place to sit for an hour or two.
If you walk past the frontage of the pub, you will see a very optimistic cricket pitch ahead of you – walk down the right-hand side of this until you reach a stile. Cross the stile and head up the hill, keeping the woodland on your left hand side.
This is a steep section but offers fantastic views back across Woolesthorpe and out across the Vale of Belvoir. You can see just how flat the land is all the way out to the Trent to the east. Straight ahead, you can see Belvoir Castle on the top of the hill.
View from the top of Woolesthorpe Hill
Point 9
When you reach a stile on your left hand side, go through it and follow the footpath past an area of recently cleared woodland. When you reach the road, turn right and follow it to a bend. This section does not have a pavement and cars can travel quite fast along it so walking on the wide grass verge is recommended! Luckily the walk only takes a minute or two.
Point 10
When you reach an s-bend in the road, you will see a house on your right and ornamental gates which lead into the Belvoir Estate. On your left is a track which takes you down to the canal – this is where the bridge we encountered along the canal would bring you to. Instead, we want to take the track to the right which takes you away from the canal and through an area of young woodland. This is the Viking Way.
The track winds along between arable fields, bordered by hedgerows with sweet chestnut trees as standards all along. If you like chestnuts, it is well worth bringing a bag along to fill if you are planning a walk along here in late September or early October.
The ease of walking along here does vary, depending largely on whether the various 4×4’s or trail bikes have been obeying the signs and keeping off. The restrictions on them vary but they are often permitted to use the route at certain times of the year when the disturbance and damage they cause can be enough to make it tough going for much of the rest of the year.
Point 11
The track will soon reach a railway bridge and a row of houses will appear just afterwards on the right hand side. Cross over the bridge and turn immediately left to drop down the bank and follow the path of the old railway to the left.
You will pass a damp pine plantation to the left where woodpeckers can often be heard drumming on the trees or cackling their cry. On the right hand side soon after, you will pass a lake where you might be lucky enough to spot a heron stalking the shallows.
On the approach to a second bridge, where we leave this section, you will see a lot of young ash trees lining the sides of the old railway line and forming a light canopy over the track. Ash is a relatively quick growing species and often colonises abandoned locations such as this. Walking along this section, take a moment to consider how different the landscape would be if ash were to go the way of English Elm as a result of Ash Dieback disease.
View across the fields to Denton Church
Point 12
When you reach another bridge, take the track which brings you up to the right of it, just before the bridge itself, and come back out onto the road. Turn right and follow the road down and into the village of Denton. Again, we are on a stretch of road with no pavement and potentially fast cars so do be careful for a few hundred metres until you reach the pavements which carry you safely through the village.
As you enter the village, just beside the Denton sign, there is a patch of butterbur on the left hand side. The great wide leaves and tall flower spikes look rather prehistoric and are very noticeable in May when they are in flower. This is a species often associated with wet habitats and the stream which passes just beside these plants explains their position here.
As you pass through the village, you will see the village hall on the right hand side. This is one of the buildings from the WWI encampment at Belton Estate during the war when a machine gun training ground was located there.
The road will bend left, then shortly right to head uphill towards the A607. Walk along until you see a footpath sign indicating you to turn off to the left.
Point 13
Follow the footpath down a narrow jitty between two hedgerows and out into a field. Walk ahead and slightly right to cross a stream at the bottom of the field where there is a bridge to the right of dense willow. There are often cows in this field so be sure to keep dogs on leads.
As you enter the field, take a look to the left where you can see an impressive old oak in a private field behind the houses as well as a beech on the field boundary.
After crossing the stream, head back uphill to a stile which opens onto a track.
Point 14
Turn right along the track for about 20m, then leave it again over a stile to your left. Follow the path diagonally across the field to reach a gap in the hedgerow at the far corner.
If you look to your left as you walk, you can see the canal which you just walked and another nice view out across the Vale of Belvoir.
View from the A607 – the ladybird balloon is a familar sight on nice summer’s evening across the Vale of Belvoir
Go through the gap, (carefully!) cross the A607 and go straight over the stile into the field opposite. Then take the track diagonally to your left to cut off the corner of the field and reach a gate which will bring you back into the village of Harlaxton. Walk through the two gates and then continue along the road which the footpath becomes.
Point 15
When you meet another road at a T-junction, instead cross over and go through a gate into the field. Cross this field along the footpath and go through two more gates to bring you out into the churchyard of Harlaxton Church.
Walk across the front of the 13th Centuary church (look out for the gargoyles as you go) towards a large copper beech.
This is recorded in the Woodland Trust register of coronation trees which were planted to mark the coronation of the queen in 1963.
To the left of the beech is a small carpark and, just to the left of this, a track which leads you down the side and brings you back out opposite the monument at the start of your walk.
Cold and snowy weather can be the perfect time to go and visit larger waterbodies where all the water fowl are often far away – as the ice closes in, they are generally pushed closer together where they manage to keep a small area of clear water where they all then congregate. Whilst I’m sure they aren’t too pleased with the weather, this does often make them easier to see! And if you’re lucky, you might even enjoy the sight of one trying to land one the ice as in the case of the mute swan – this year’s judging by the greyish tinge to the plumage!
Mute swan landing on ice at Denton Reservoir (click for a larger quality picture)
Denton reservoir is located in the village of Denton, just outside of Grantham. It can be accessed by footpath from the village and is well worth a visit at any time of year. Lincolnshire County Council have produced a walking route which takes in the reservoir as well as the villages of Denton and Harlaxton – you can download a copy here or pick one up from Grantham Library.
I spotted a total of nine species at the weekend which are illustrated below.
Mute swan
Tufted duck and Pochard
These two species are quite similar at first glance and you might be forgiven for thinking one was the male and one was the female! The black and white diving ducks, with the little tuft extending back from the head, are tufted ducks whilst the brown-headed pochard is the chap with his head tucked under his wing in the bottom left of the photo. Don’t be distracted by the white-nosed coot’s, they’re featured further down.
Cormerant
Often thought of as a sea bird but often seen inland. Similar to a shag but shags are very rarely seen away from the coast.
Cormerant at Denton ReservoirCormerant in flight at Denton Reservoir
Great crested grebe
Often one of the shyer species, this is a good chance to get a good view of them. There are two on the ice and one braving it out on the cold waters with his head under his wing.
Mallard
A species which will be very familiar to most – the males are the brightly coloured chaps whilst the drabber females are dressed in brown. They’re all taking care over their appearance in this photo!
Coot
These are often quite territoral little creatures for much of the year, even chasing swans away from their patch. Perhaps it’s the sheer futility of being territorial in such a small space which calms them down at this time of year – they all looked to be getting on well.
Canada goose
Whilst none of these photographs are award winners, this is the worst of them all – it wasn’t until I got back that I realised the camera had focussed a little behind the geese! There are often large flocks of these geese, along with the greylags, but these were the only two when I visited.
I spent several nights this September cycling along Grantham Canal with an EM3 bat detector connected to a GPS unit, recording the bats in flight between the A1 to the east and Hickling Basin to the west. Bats use echolocation to navigate and hunt and the bat detector converts this ultrasonic sound into something we can hear. The sound emitted by the detector tells you when a bat is there, often which species it is and sometimes even what it is doing.
Grantham Ecology 