Easegill Caves Hibernation Surveys

The Cumbria Bat Group kindly let me come along on a hibernation survey at Easegill Caves in January 2017. We hiked up to Upper and Lower Kirk Caves to see what we could find, then descended using ropes and caving ladders into Link Pot to explore an underground cave network some 15m down.

We found good numbers of myotis species including Daubenton’s, Natterer’s and whiskered/Brandt’s/Alcathoe – these last three are grouped as it’s very difficult to distinguish these three without disturbing the bats. We also found a small number of brown long-eared bats hibernating too.

It’s important to note that disturbing hibernating bats is illegal without a licence from Natural England – this survey was led and supervised by licenced bat workers who ensured that disturbance was kept to a minimum whilst allowing the bats to be identified and counted. If you find a bat in roosting you should take great care not to disturb it especially during the winter as they may rouse from torpor at an inappropriate time and be unable to then survive the winter. If you do find a roosting bat – let your local Bat Group know! More details at the bottom…

The video below shows a summary of the seven hours we spent out in the hills, in just under three minutes!

The following photographs show a few of the hibernating bats we identified on the surveys.

It’s not only bats we found in the caves – plenty of cave spiders and hibernating moths too including herald and tissue moths.

If you would like to get more involved with your local bat group and help out on hibernation surveys such as these, you can find your nearest here. Many thanks to the South Cumbria Bat Group, and Rich Flight in particular, for a great opportunity to explore the caves and see plenty of roosting bats!

32099982730_6610676755_o.jpg

 

Advertisements

2016 in Butterflies

I thought I had probably seen my last butterfly of 2016 when I started to put together this collection for 2016 – only to see a peacock flitting around on my lunchtime walk yesterday. Sunny weather or disturbance can bring out some of our hibernating species during the winter so the ‘season’ never truly ends!

img_7409_26426271114_o
This green-veined white butterfly was feeding on the greater stitchwort flowers in the Nottinghamshire Wildlife Trust reserve Treswell Woods earlier this year. A closer view reveals the yellow pollen from the anthers on the legs of this butterfly which will likely be transferred to the next stitchwort flower on which the butterfly alights. This act of pollination is the reward which the flowers get in return for their nectar they provide.
26533702073_c07f16361b_o
This is a close-up photo of a orange-tip butterfly – I love the chequer-board green eyes. This individual was resting with folded wings on a white flower and their camouflage really is superb in this pose – until their open their wings and reveal those gaudy orange wing-tips from which they derive their name.
26861968030_8bab48a1c5_o
This year was a good one for dingy skippers – I was lucky enough to see them at a number of different sites.This was at a Warwickshire Wildlife Site – Harbury Spoilbank – where grizzled skippers and green hairstreaks are also to be found. This is a male and a female pre-mating in the low vegetation.
img_9666_26530235404_o
Another skipper from another Warwickshire Wildlife Site – this time at Ufton Fields. This is the grizzled skipper, a tiny little butterfly which could easily be mistaken for a moth at first glance as it zips past. This one is feeding on a speedwell flower.
img_1235_26613081363_o
This is one of the UK’s rarest species – the wood white taken at Ryton Woods in Warwickshire. I took a walk around the rides hoping to spot this species and was just about to give up hope when this one appeared, bouncing along the edge of the rides. Their flight is slow and delicate and the males spend much of their time patrolling in search of females on the vegetation. I followed this one a while and got just one or two photos before he fluttered on over some dense scrub away from the path and out of sight.
img_3597_27367381901_o
This is a common blue butterfly perched on one of their favourite food plants – the bird’s foot trefoil. I like this photo as you can see the curled tongue protruding. This long tongue straightens when they feed, allowing them to reach nectar from deep within the flowers and to access resources that many insects cannot.
27401028642_f93b30c64b_o
This photograph of a common blue was taken at sunset at Muston Meadows NNR in Leicestershire. The butterflies settle on vegetation such as this, always seemingly adopting this downwards-facing pose, at the end of the day. This one tried several locations before finding a position it was happy with. The butterflies spend the night roosting like this, ready to awaken when the temperatures rise again in the morning.
img_4888_27521459425_o
This orange tip was displaying the colouration which gives the species its name, although it is only in fact the male butterflies which have orange tips – the female butterflies have black tips. Orange tip butterflies favour flowers of the cabbage family and this individual alighted and then departed several non-cabbage flowers before settling and drinking deep from these dame’s violets growing along The Drift SSSI.
img_6292_27609463746_o
I think it’s only fair to include a raggedy painted lady butterfly in this collection, considering the journey these butterflies make to get here. This was taken feeding on hogweed along the Grantham Canal – many miles inland from the sea across which this butterfly had flown to get here. This species does not breed in the UK which means that every individual you see will have migrated from the continent.
28539415506_66cb688356_o
I rather liked the angularity of this photograph of a marbled white in a slightly unusual pose. I do not know of a site local to me where these butterflies are found, but they occur in good numbers in many grassland sites in Warwickshire where I have spent some time this summer. These butterflies seem to favour thistles – newly emerged individuals will alight temporarily on all sorts of purple flowers – from ragged robin to orchids – until they get their eye in for the thistle flowers they are seeking.
img_5740_29617085931_o
2016 wasn’t a good year for the small tortoiseshell with low numbers recorded through much of the summer. I saw a few more in the later months, such as this one feeding with several others on a patch of thistles in a pasture field. Nettle and thistle often come to dominate patches of higher nutrient ground within pasture fields. The imago – adult butterflies – love the thistle flowers, and their caterpillars feed on nettle, so this combination of species is ideal habitat for small tortoiseshells.
img_7338_30234219751_o
A red admiral to finish – these are one of our few species which hibernate along with small tortoiseshell, comma, peacock, speckled wood, clouded yellow and brimstone butterflies. This individual had found the patch of naturalised Michaelmas daisy in the grassland above Grantham in October, along with a range of bees and hoverflies – and was taking advantage of the nectar source and autumnal sunshine before finding somewhere dark and stable to fold its wings and await the spring.

 

 

 

Brimstone butterflies – the perfect harbinger of spring

Brimstone butterflies are the perfect harbinger of spring. They are typically the first butterfly seen in most years – excepting the occasional tatty small tortoiseshell or peacocks – and they always look pristine. Perhaps the connection with spring is so strong because they confirm our own perception of the first spring day – they need the warmth and clemency of sun and still blue-skies in February or March to take to the wing.

Brimstone  (Gonepteryx rhamni)
Brimstone (Gonepteryx rhamni)

I saw my first brimstone of 2014 a couple of week ago but they were out in abundance last Sunday – settling on the south-facing hedge in the garden to warm up and bask in the sunshine. A short drive across the Vale of Belvoir saw almost every hedge graced with at least one which bobbed and bounced around the periphery of the foliage.

The brimstone is one of five or six species of butterfly which hibernate in the UK. You may see much tattier and battered small tortoiseshell, comma and peacock butterflies at this time of year along with the occasional clouded yellow and, increasingly, the red admiral. All of these, excepting the brimstone and the clouded yellow, are in the Nymphalidae family – a group which includes many other familiar UK butterflies including the fritillaries and the browns. The brimstone is in the Pieridae family which also includes the whites.

Hibernating peacock butterflies which find dark places such as sheds, roof spaces, tunnels and tree cavities to close up their wings and wait for spring to return.
Hibernating peacock butterflies which find dark places such as sheds, roof spaces, tunnels and tree cavities to close up their wings and wait for spring to return.

Brimstone butterflies are a single brood species – the adult butterflies emerge in August and are on the wing, feeding and building up fat reserves, until they go into hibernation at the end of autumn. The butterflies, also called imago, re-emerge early in the spring to mate and begin their life cycle once more.

The comma and small tortoiseshell butterflies, in the Nymphalidae family, tend to have two broods in a year – that is the first batch of imago will mate and lay eggs which hatch and give rise to a second batch of imago in the same year. The red admiral has a single brood but the prevalence of imago is affected by migrating butterflies from the continent. The peacock has rather a similar life cycle to the brimstone.

It is always noticeable that the brimstone butterflies look pristine in spring, whereas the commas and small tortoiseshells often look much more battered and tatty. I was hoping this might be explained simply by the Nymphalidae butterflies being older – that is they had been on the wing longer in the previous season before hibernation, but the phenology doesn’t seem to bear this out for all. It could explain the particularly tatty comma and small tortoiseshell butterflies, if some of these are surviving stragglers from the first brood of the previous year.

Comma butterfly (Polygonia c-album)
Comma butterfly (Polygonia c-album)

 There is still a difference in family between the brimstone and all of the other hibernating butterflies and I wonder whether the brimstone is simply a more structurally sound butterfly, with stronger wings which are less likely to deteriorate than the other species. The species is the longest living of the UK species, at a year, so the imago would need to be hard-wearing! I would be fascinated to know an answer to this if anybody can advise.

Small tortoiseshell (Aglais urticae)
Small tortoiseshell (Aglais urticae)

The brimstone butterflies feed on a range of nectar sources – as they are so early to emerge they rely initially upon long-flowering species such as dandelion, or early flowering species such as bluebell, cowslip and primrose. The key food plant in the autumn is thistles with a range of other species also used.

The larval food plant is surprisingly specific and not abundantly common – they require buckthorn or alder buckthorn. The species name for the butterfly eludes to this link – rhamni which refers to the latin for buckthorn – Rhamnus sp. This is a shrub which can be found in hedgerows and woodlands but is not nearly as common as other similar species such as hawthorn or blackthorn. I do not know of any buckthorn in the area but the presence of the brimstone butterflies clearly proves its existence! The comparative scarcity of buckthorn has been directly addressed by Butterfly Conservation in the past with planting programmes to increase their presence within landscapes and this has had a positive effect on the brimstone populations.

The female is much paler than the male – I saw one in the distance on Sunday which I at first through to be a large white until I crept closer and saw the distinctive veined, contoured folded wing which looks so much like a leaf.

Brimstone  (Gonepteryx rhamni) pretending to be a leaf

February Hibernation Survey at Harlaxton

Last Sunday was one of those beautiful days when everybody feels spring is just around the corner. The garden was filled with birdsong and sunshine, neighbours decided it was finally time to venture out and sweep those autumn leaves, daffodil bulbs bulged yellow at their tips where flowers are just waiting to appear.

What better day to descend into a sealed up tunnel, feeling the temperature drop steadily on a headlamp-lit thermometer, to search for hibernating bats!? Along with another member of the Lincolnshire Bat Group, we gallantly left the sunlight behind to see what we could find.

Entering the tunnels

In the past we have come across hibernating barbastelle bats, a rare species in the UK and here, at almost the northerly limit of their range, but sadly this time they were absent from the deep cracks which staircase down the brickwork where the tunnel curves.

Several years ago the Bat Group put up boxes in the tunnel, to provide a greater range of roosting opportunities and in here we did find some bats – two boxes had brown long-eared bats sleeping soundly inside, their long ears tucked behind their wings with only the tragus – the fleshy projection within the ears – apparent.

Hibernating brown long-eared bat

Only one of these bats was present during the January survey which means that some time in the last month, the other has flown and found this as a new place to enter torpor. This is not uncommon, bats will rouse during warmer winter weather and will often feed briefly before returning to their torpid state.
Along with the bats were around 60-70 peacock butterflies, all with their wings tightly closed and apparently oblivious to our torchlight as we passed by, careful not to disturb them. Many had damaged pieces of wing from last year – the first butterflies of the year are often tattered old veteran tortoiseshells, peacocks and brimstones.

Hibernating peacock butterflies

A number of herald moths were also present, including the pair pictured below who appeared to be hibernating upon a spiders web! I would love to hear any feedback on this interpretation – I do not think they have fallen prey to the spider as this same pair were present last September when I checked the boxes were ready for the winter and are apparently still alive and well! They will take flight when the weather warms, sometime between March and May.

Hibernating herald moths

If you are interested in joining the local bat group, visit their webpage for details – there are events throughout the year that you can take part in. For details of your local group if you are outside of Lincolnshire, the BCT webpage has all the info.

What do you need to climb-and-inspect trees for bats?

I have put this post together as a brief guide for anybody wanting to know more about what is required to climb and inspect trees for bats. When I was looking into the requirements, I couldn’t find anything which simply set out the steps so I hope this will be useful!

Climber in an oak treeTrees can be difficult to assess for bat roosts. Sometimes you can spot a feature – a woodpecker hole, split or fissure for example – which you can identify with reasonable confidence as a bat roost, perhaps by signs such as scratch marks, fur rubbing or droppings. But, in my experience, these types of features are the exception. You are much more likely to spot, what Henry Andrews would call, PRF’s or Potential Roost Features – see his website here for perhaps the best resource I’ve come across dealing with the use of tree roosts by bats.

You might want to be have more confidence in your assessment for a range of reasons; perhaps as a local bat group simply gathering data on local roosts, perhaps as part of research into bat distribution or movement, perhaps to protect the bats for example if the tree is dangerous and must be removed.

There are two approaches that can then be taken. Firstly, you could carry out a dusk/dawn emergence survey to watch for bats leaving or returning to a roost. This is quite labour intensive and has a number of limitations, such as the difficulty in being confident that a bat appeared from a particular location and the transient use of many roosts providing little confidence in a negative result. A second option is to inspect the feature closer up, using an endoscope perhaps to look within and see whether there are any bats residing within and whether the feature is actually as suitable as it may appear from the ground.

In order to carry out this “climb and inspect”, you will need two things:

Firstly, a licence to disturb bats with a handling endorsement. This is because bats are legally protected under both domestic and European legislation and it is an offence to intentionally or recklessly disturb them in their place of rest. See the BCT website for more info. This licence requires a large amount of specialist knowledge and experience of bats and their roosts. If you are interested in gaining the experience and, ultimately the licence, getting in touch with your local bat group is the best place to start. If you are already working in a professional capacity, I can highly recommend the Bat Licence Training Course run by Richard Crompton and Sandie Sowler.

Secondly, you need the competence and equipment to safely ascend to the feature. The basic qualification for this is the City and Guilds CS38 – Tree Climbing and Aerial Rescue Operations course. This not only teaches you the basics of climbing but also how to rescue somebody from a tree – if an accident does occur, it is critical that you know how to safely bring somebody down to the ground where they can be treated. This is usually a week long course which takes you through the principals, the theory, the legislation and the best practise for tree climbing before teaching you the practical techniques of climbing. At the end of the week, there is usually a separate assessment taking several hours where your competence will be assessed. As well as the climbing technique and principal, there is a requirement to identify a range of common tree species so this is something to brush up on beforehand. Another hint – you will probably not need to spike up trees for climb-and-inspect work, this is damaging to the trees and is only to be done if you are an arborist who is going to take the tree in question down (or in an emergence rescue situation).

Once you are qualified to climb, there are a few more things you will need before you can start:

1) The climbing equipment. The basic kit consists of a harness with leg-loops, rope, prussock cords, caribinas and a secondary support strop. These must all conform to the minimum legal requirements.
2) The safety equipment – this includes a helmet with a chin-strap, a knife with a retractable blade, a first aid kit and sturdy (steel toe) boots. High visibility jackets are also useful, especially for a groundsman. See point 3…
3) A groundsman! If something happens in the tree, you must have somebody with you who is qualified to climb and perform an aerial rescue. This might be required is for example there is a problem with your equipment meaning you can’t descend upon it, or if you were to hit your head and become unconscious. You should only ever climb if you have this second qualified climber on the ground the entire time that you are in the tree.
4) The kit to inspect the feature – an endoscope is either an eyepiece or, commonly now, a screen attached to a fibre-optic snake which allows you to see around corners and in deep, dark cavities of trees where bats might be hiding. This has the potential to cause disturbance to bats which is why the relevent licence and experience are critical. Other pieces of kit which might be useful include binoculars, a torch and a mirror!

If you were climbing for your own pleasure on your own land, this may be all that you require. However, if this is being undertaken in any kind of professional capacity, you would also need the appropriate insurance in terms both of personal safety and public liability.

For more information on the assessment and CS38 qualification, you can see the assessment criteria provided by NPTC here.

I work for a local Ecological Consultancy based in Grantham and we do offer professional climb and inspect services in the East Midlands area and beyond – if you would like more info then drop me a message and I will get in touch with you!

Potential Roost Feature (PRF) worthy of closer inspection!
Potential Roost Feature (PRF) worthy of closer inspection!

Hibernating moths and butterflies

A recent trip to look for bats in Harlaxton railway tunnel didn’t reveal any – it’s still a little early for them to be hibernating – but plents of moths and butterflies were preparing to hibernate for the winter. The tunnel gets cold but the conditions are stable and this allows the insects to enter a torpid state until the weather warms up again. Herald moths prefer dark places and where you find them, the chances are conditions will be good for bats too! Several of the herald moths were hibernating on old spider’s webs – this isn’t something I’ve seen before but seemed to be a populat location, at least half of them were hanging in this way. The peacock butterfly was recently arrived as he was still quite active, flapping his wings slowly when the torch fell upon him, but plenty more had their wings folded tight and looked set to sleep out the winter already!ImageImageImage

Awakening ladybirds

Anybody who has been out in their garden over this weekend of beautiful spring weather will probably have noticed quite how many ladybirds are waking up and sunning themselves. They have hibernated through the winter, in clusters, but they are spreading around once more.

7-spot ladybirds

The ones photographed here are the commonest UK species – the seven spot ladybird. Their scientific name is another example of a nice agreement between the latin and the common names; Coccinella 7-punctata – punctata meaning a point. Interestingly, the seven-spot ladybird can have between 0 and 9 spots but 7 is the most common.

Ladybirds are useful additions to anybody’s garden – their larvae are voracious predators and be very happy in the greenhouse devouring aphids and other small pests.

7-spot ladybirds

There are 46 different species of ladybird in the UK but you would recognise 26 of them as ladybirds with their distinctive shape and colouration. There are several online guides to the other species including an app for the iPhone. The FSC field sheets are a brilliant handy guide to many common species and habitats and their app includes the ladybird ID guide for free, with the option to buy more ID guides within the app. You can also use the CEH’s online ID tool or a simple sheet showing you the different species from the ladybird survey website.

Harlequin ladybird
Harlequin ladybird

Some species of ladybird are in decline in the UK and experts want to know how much of an impact the harlequin ladybird (Harmonia axyridis) might be having on the native species. The harlequin is an invasive species from North America and is easily distinguishable from the natives. There are plenty of harlequins around Grantham, including these which woke up on the windowsill in our office. You can record sightings of harlequin ladybirds at this website and help to keep chart the spread of this species.

The UK ladybird survey also welcome records – if you are unsure of your ID, you can send them a digital photograph and this can be used by their experts to determine just which one you have. Their website, with links to recording forms, is here.