Glasgow & SW Scotland Butterflies

The Breeding Bird Survey (BBS)  is the British Trust for Ornithology’s flagship bird survey and has been running since 1994. The BBS is a line-transect survey based on randomly selected 1 km squares. It has been very effective in monitoring UK bird populations and has shown changes over time and regional differences. For example, declines in starling populations have been detected all over the UK whereas willow warblers have declined in England but increased a little in Scotland over the 1994-2009 period.

While the UK Butterfly Monitoring Scheme (UKBMS) has been very effective at monitoring populations trends of both rare and common butterflies, these transects are mostly at sites which are good for butterflies and are therefore biased. To get data on butterflies in the wider countryside, the Wider Countryside Butterfly Survey (WCBS) was rolled out in 2009. And WCBS is based on the BBS transect methodology and used the same random selection of 1 km squares to get an unbiased (in contrast to UKBMS) survey in the wider countryside.

In 2009, there was a dual approach with some 20 random selected 1 km squares being allocated to each Butterfly Conservation branch area and bird recorders who participate in BBS were also invited to re-visit their squares for butterflies in the summer.

This article is about the WCBS results from three BBS squares in 2010 which I survey for birds.

NS5057 is at Springhill just south of Barrhead in Renfrewshire and in terms of birds has the greatest number of species with a peak of 42 species recorded in 2006. The rarer species recorded there include lapwing (in 2006), sedge warbler, dipper, yellowhammer and whitethroat.  

Is it logical to expect the 1 km square with the greatest number of bird species to have the greatest number of butterfly species? As intensive farming is thought to reduce biodiversity in general, then yes, this would be a logical expectation.

NS5057 is quite rural and the land use is unimproved grassland which is grazed by cattle, sheep or horses or allowed to grow and is cut in mid-summer and some other fields don’t appear to be subject to any management. There are also a few areas of woodland.

Butterfly Results for NS5057

So NS5057 had a total of 81 butterflies of five species recorded over the three visits.

NS4060 is at Howwood near Johnstone, Renfrewshire and is another quite rural 1 km square although in this case there are some barley fields and the first half of the transect runs through three improved pastures which are cut during mid-summer. The second half of the transect is quite varied with some wild grassy areas, unimproved pastures lightly grazed and a area of houses with waste ground. From ornithological point of view, this square has a species which has declined dramatically in recent decades owing to modern farming methods: the Grey Partridge.

Butterfly Results for NS4060

So NS4060 had a total of 40 butterflies of five species recorded over the three visits.

The Small Copper below was one of two basking on an area of dried mud at a gate separating two fields. For most of the year, this gate area is a mud bath but in summer, it can dry out to form warm basking areas for Small Copper.  This is one example of how grazing animals can favour butterflies although often it is not just the creation of bare araes for basking but also the creation of disturbed soil which provides suitable ground for the larval foodplant to grow in.

Small Copper at Howwood 15 August 2010

NS6153 is the most urban of the three squares and is located at East Kilbride, Lanarkshire although parts of the transect are somewhat rural. Since 2004, there has been a significant land use change in this more rural area with conifer plantations being felled to give way to an area of birch scrub regeneration. This led to Goldcrest disappearing from this area and Whitethroat appearing together with more Willow Warbler.

Butterfly Results for NS6153

So NS6153 had a total of 44 butterflies of four species recorded over the three visits.

Small White was present in this more urban square which is expected as Small White (and Large White) is associated with brassica growing which is more common in areas where people live. The Small Tortoiseshell were found nectaring on flowers along a stream on the transect.

The results show that the two more rural squares, NS5057 and NS4060,  had a greater number of species, five, compared with the more urban square, NS6153, four. In terms of total butterfly numbers, NS5057 had the greatest number of 81 while the more urban square, NS6153 unexpectedly came second with 44.

As someone who is intimate with these squares so to speak as a result of bird surveying in them twice a year, I was surprised by how many butterflies were present. This was particularly true of the urban square, NS6153, at East Kilbride which I expected to be a wasted effort.

It is possible that Meadow Brown and Ringlet were more numerous this year, especially in NS5057,  as the cold winter followed by the dry spring delayed grass growth significantly. The first visit occurred when many of the grass fields had not been cut and in most years, a cut may well have been made by late June/early July. Far fewer Meadow Brown were encountered during the second visit when some of the fields had been cut.

Overall, this exercise has been very successful in detecting common butterfly species in the wider countryside: green-veined white; meadow brown; and ringlet. The more interesting species were:

1)  common blue in a field grazed by horses in NS5057 which supported the foodplant, bird’s foot trefoil.  

2) small copper in unimproved pasture at NS4060 on bare ground created by livestock at a gate.

Written by Andrew Masterman

Late August and September is the time when large numbers of Peacocks, Red Admiral and Small Tortoiseshell can sometimes be seen on buddleia. But the ones I have seen near where I live in Glasgow’s southside are sadly bare of butterflies.

Peacocks emerge during August and I saw quite a few Small Tortoiseshell in East Kilbride in 29 July so there ought to be some butterflies on buddleias. I have only seen one Red Admiral and one Painted Lady this year so large numbers of these are unlikely to be seen on buddleias this year.

Peacock Credit: Scott Shanks

Please report your butterfly sightings on buddleias by adding a comment. If you provide a grid reference, place and date and your name too, the sighting can be recorded as a record by the Branch Recorder, Scott Shanks.

Written by Andrew Masterman

2010 was the second year of Chequered Skipper Surveys in Argyll and Lochaber organised by the branch. And while not all records are in yet, I can report some exciting new records in and around Taynuilt.

Distribution of Chequered Skipper Records around Loch Etive

The only previous Chequered Skipper records on the south side of Loch Etive were a bit further north but in 2010, there were five just east of Taynuilt including two along Glen Kinglass and one in Taynuilt itself at Brolas Farm which is a well-known Marsh Fritillary site. This site is visited most years for Marsh Fritillary so Chequered Skipper would certainly have been spotted before by visiting Lepidopterists if not by the inhabitants of Taynuilt so this new record must reflect recent colonisation rather than under-recording.

There appears no obvious reason why Chequered Skipper should not be found further south in Argyll than Loch Etive as its foodplant, Purple Moor Grass is abundant throughout Argyll and coastal parts south of Oban also have a mild and very wet climate like North Argyll and Lochaber. It remains to be seen whether there is further spread of Chequered Skipper along the south side of Loch Etive in future years but it would be good if it did so because its current very limited distribution of 30 10 km squares makes it vulnerable when colonies go extinct.

Next year, it would be interesting to see if Chequered Skipper can be found further west than Taynuilt. If it turns up in Connel, then it is possible it could spread to the Oban area which would be great.

Here are some photos of Chequered Skipper and Chequered Skipper sites taken in 2010:

Male CS at Glasdrum 29 May 2010 Credit: Andrew Masterman

Male CS at Creagan 28 May 2010 Credit: Andrew Masterman

CS Site East of Taynuilt NN037332 Credit: Owen Figgis

CS site Glen Kinglass, Loch Etive NN083373 Credit: Owen Figgis

CS site Glen Noe, Loch Etive NN053346 Credit: Owen Figgis

CS site Creagan Buidhe, Loch Etive NN058356 Credit: Owen Figgis

Written by Andrew Masterman

Although we have yet to receive the first sighting of a Scotch Argus in 2010 on the date of writing this blog post (21 July 2010), the first ones are very likely on the wing now.

While the Scotch Argus can be found in much of highland Scotland and in parts of southern Scotland, the greatest numbers occur in Argyll where for a few weeks from late  July to early September each year, the multitudes of this stunning butterfly are an amazing butterfly spectacle! You can find them everywhere in Argyll: along roadsides; in woodland rides; on hillsides, on coasts etc. Although they are only on the wing for two months of the year (mid-July to mid September), the Scotch Argus is Argyll’s most numerous butterfly.

As the flight period progresses, Scotch Argus become progressively more worn and tatty. To see Scotch Argus at their best, you need to visit Argyll between late July and mid-August on a sunny day although if you want to photograph them, choosing a warm cloudy day is the solution. The following Scotch Argus photos were taken at Bridge of Awe NN033302 on 26 July 2008 when warm but cloudy conditions meant the butterflies were sufficiently inactive to make photographing them possible. This Bridge of Awe meadow is a great butterfly site worth stopping at anytime from May to September as you are guaranteed to see a number of butterfly species on a sunny day.

So a trip to Argyll is strongly recommended between late July to mid August to see Scotch Argus in their prime and in multitudes. Good places to stop and look for Scotch Argus and other butterflies are shown on this spreadsheet which details the results of a voluntary survey I did in Argyll during the lovely warm dry summer of 2006.

Andrew Masterman

In recent years we’ve seen a significant increase in the number of Comma sightings in SW Scotland. Until now these records have all been of adult commas, but thanks to Heather Young of the SW Scotland branch we now have proof of Commas breeding in the branch area.

Comma Caterpillar 13-07-2010

On the 13th of July, Heather found this nearly full grown caterpillar on an elm near Bridge of Allan, Stirlingshire (NS788988). She suspects it was wych elm, but is having the elm species confirmed by a botanist to be sure. The caterpillar began to pupate a few days later.

There have been only 2 other records of comma caterpillars in Scotland in recent times. On both occasions they were in the Borders. The first was seen in 2006 at Sprouston near Kelso, on elm, and the second at Duns in early July 2010, on nettle.

The Comma caterpillar is quite distinctive, with a large white patch at the rear of the body which gives them the appearance of a bird’s dropping. The mature caterpillar will sit happily on the upper surface of leaves, trusting in their bird-dropping mimicry to keep them safe from predators. In England and Wales comma caterpillars can be found on stinging nettles, elm, wych elm, hops and occasionally currents. The pupa resembles a dried leaf dangling from the food plant and is much harder to find!

If you are out for a walk and pass patches of nettles or a stand of elms in SW Scotland keep an eye out for Comma caterpillars (and adults!) and let us know.

Heather Young & Scott Shanks

Caterpillar photograph (c) Heather Young 2010.

The Pebble Hook-tip is one of six species of moth belonging to the family Drepanidae which occur in the UK. Hook-tip refers to the tips of the forewings which are strongly hooked.

The photo below was taken at Glasdrum on 29 May 2010 during the Chequered Skipper weekend and is of the scotica sub species.

 Pebble Hook -tip

If you are unsure of the difference between the underwings of a Pearl-bordered Fritillary and Small Pearl-bordered Fritillary, compare the next two photos.

Pearl-bordered Fritillary

Small Pearl-bordered Fritillary

The following is the upper-side of the same Pearl-bordered Fritillary.

Pearl-bordered Fritillary

Now for something completely different!

 The Tussock moths of the family Lymantriidae are so-named because of the characteristic tufts of hair on the backs of the caterpillars. The caterpillar of the Dark Tussock is a good example as it has white tufts either side of a black stripe in the middle of the body with yellow tufts at either end!

Dark Tussock caterpillar at Schiehallion 26 May 2010

This second photo of another Dark Tussock caterpillar is quite kitten-ish!

Another Dark Tussock caterpillar near Trinafour, Perthshire 17 may 2010

Talking of hairy caterpillars, the “Woolly Bear” caterpillar of the Garden Tiger must now be mentioned. This amazing caterpillar is presumably a good example of how evolution by natural selection can produce extreme morphology!

“Woolly Bear” caterpillar of the Garden Tiger at Schiehallion 26 May 2010

The Broad-bordered White Underwing is a Red data Book  species found only above about 2000 ft in Scotland although one was recorded on the summit of Cheviot in Northumberland on 12 June 1974. Most Scottish records are from the central Highlands. Twenty five were found near the summit of Meall Breac (802 m) on the south-east side of Loch rannoch on 31 May 2010 and a further three on neighbouring Geal Charn.

Broad-bordered White Underwing on Geal Charn 26 May 2010

An even rarer mountain moth is the Small Dark Yellow Underwing which is classified as Nationally Scarce A.  This mountain moth flies very fast and occurs in low numbers and is very difficult to detect. One was found on the top of Meall Breac, Loch Rannoch after 4 hours searching and another found on Schiehallion after 5 hours searching. A very attractive moth but a real blighter to find!

Small Dark Yellow Underwing Meall Breac 31 May 2010

Another moth of the mountains is the Emperor which is the only UK member of the moth family Saturniidae. The large green caterpillars with pink spots which you can find on heather in August are spectacular but so too are the adults! The photo below is of the larger female - an Emperess? - which is quite mesmerizing.

Female Emperor moth at Schiehallion 19 May 2010

Another moth characteristic of heather moorland is the Common Heath and the males have spectacular feathered antennae. 

Male Common Heath at Schiehallion 30 May 2010

Returning to butterflies, the Green Hairstreak is a butterfly which can be found on heather moorland as its caterpillars feed on Blaeberry.

Green Hairstreak at Trinafour, Perthshire 17 may 2010

Written by Andrew Masterman

We are looking for volunteers to help with a national (UK) survey of butterflies during 2010.

A pilot survey had been run for a few years down south and was rolled out nationally last year. It requires each region in Britain to undertake a survey of up to 25 one kilometre squares two or three times a year during the summer. Last year we only managed to survey one third of our allocated squares and are keen to do better this year. The squares are distributed to each region by a random computer allocation, this is to give the project a scientific robustness. All squares are assessed in exactly the same way so if these squares are surveyed again in the future it will be in the same fashion, even if by a different volunteer.

Often surveys depend on individuals choosing places that are local, convenient or likely to be rewarding for finding butterflies. All good reasons for surveying, but means that other areas not so obviously appealing are overlooked. In order to overcome such a selection bias this survey has been set up to look elsewhere in a region, essentially to see what is out there.

Unfortunately this has meant that in a region like the west of Scotland some of the randomly allocated squares are in areas difficult to access. So our coverage has been less successful than elsewhere. Last year I explored two areas, one mainly a large farm and the other a hill top plantation. Neither on the face of it especially appealing, but the exploration of countryside that I would not normally visit was interesting and educational. I did see plenty of butterflies, although none were unexpected. The sighting of large numbers of Scotch Argus at the edge of the forestry plantation was rewarding. Especially as it was at the end of my final survey of the year.

The volunteers who surveyed last year area keen to examine their squares again this year, but that still leaves several squares unallocated. A minimum of two visits to each site are required, one in July and one in August, at least 10 days apart. A visit to reconnoitre the square before hand is recommended and to plan in detail the path of the survey. The organisers would like to encourage visits in May and June as well, if the volunteer is willing.

Our kilometre squares cover the area from Dumfries and Galloway to as far west as Jura and we would hope that volunteers would take on a survey of a square near to them. The vacant squares are listed at the end of this article, each is defined by OS coordinates, but I have listed approximately where they are and the type of terrain found within the square.

Briefly the survey involves walking across the square and back again in two roughly parallel lines at least 250 metres apart. The exact route will evidently depend on the terrain and access, but it does have to be described clearly and recorded in detail. My experience showed that this is a naive expectation, especially in the West of Scotland. I could have struggled in a straight line through tightly packed trees of the forestry plantation, instead I chose to keep to rides and the few open spaces. This made for a long walk, but with a friend a thermos flask of coffee we took our time and recorded plenty of butterflies. Nothing special, but we added important data to the project. Even in the middle of an extensive conifer forest Green Vein Whites abound, along with many Orange Tips. It will be fascinating to find out how they are doing after such a grim winter.

The other survey was essentially on a cattle farm. The farmer could not have been more helpful, but insisted we keep to field edges and avoid fields with cattle in them. We were happy to oblige! Consequently the trek across this kilometre square was extensive as we zig zagged around his fields, avoided his inquisitive cows and saw plenty of insects. Interestingly the butterflies seemed keen to keep close to the hedges and borders too. We counted large numbers of Green Veined Whites and Orange Tips on the first visit and plenty of Peacocks, Red Admirals, Ringlets and Meadow Browns on later visits. Like elsewhere in the UK at both sites we recorded Painted Ladies.

The method to record butterflies is the same as that used in official butterfly transects. It is really quite easy and involves recording only those butterflies (species and number) that you find or that fly into an imaginary cage 5 metres ahead of you. This ‘cage’ moves forward with you as you walk at a steady pace along the determined pathway. Once again this is very idealistic, as it is better to forget about this imaginary square when dealing with the real problems of crossing a brook, climbing over a rickety gate or avoiding frisky cows.

Butterflies that you see elsewhere are not included in the transect records, but should be separately noted. Hence there are two different recording forms that the volunteer will have to complete. Recorders are also encouraged to note day flying moths and dragon flies as well if you are confident enough to identify them. I certainly saw plenty of day flying moths and have improved my dragon fly identification skills.

There are certain weather conditions that determine when these visits can be made. Basically on a warm, sunny day when there is a minimum of wind blowing. An ideal day for butterflies and, of course, an ideal day for a walk. The exact limits and conditions are described in the detailed documents I can send out to anyone interested in volunteering.

So if you are keen then please let me know. There are plenty of species to record in the West of Scotland, but we need to have a better idea of where they are and their numbers. The data collected on a National basis in a uniform way will be a powerful source of information for Butterfly Conservation and other agencies to use in their discussions with Government (National and Local) on Biodiversity issues.

Please contact me via e mail jo.davis60@btinternet.com .

A useful website about this survey is http://www.ukbms.org/wcbs.htm

The 11 vacant sites are as follows:-click on Map reference link to see OS map of 1 km square in top right corner.

Written by Jo Davis

This survey, which began last year, is continuing through 2010.

Cinnabar moth

Like many of the commoner moths, the Cinnabar has undergone a long-term decline in recent decades (83% over 35 years, based on Rothamsted trap data) and at the UK level is now regarded as a vulnerable species (see ‘The State of… Britain’s Larger Moths’ report). It remains widespread across England & Wales, but is much scarcer in Scotland, where it is most often seen in coastal areas. Butterfly Conservation, with support from the Moths Count team, wants to learn more about where it occurs and this is most easily done by spotting the colourful orange and black caterpillars which feed on ragwort leaves, often in such large numbers that they strip the plants completely.

Cinnabar caterpillars feeding on Ragwort

The caterpillars can be seen in July and August; the equally striking adult moth has a long flight season, starting in late May and, because it is easily disturbed during the day and will fly when it’s sunny, may also be recorded during the same period.
Postcards showing both the larva and adult were widely distributed in 2009 and further publicity is planned for this year. People are being asked to send in any sightings using either the postcards or directly by e-mail to Barry Prater , the Moth Recorder for Berwickshire. barry@prater.myzen.co.uk

There was a pleasing response from BC members and others and the map shows all the 2009 records received; if you know of more from last year do please send them in.

After the cold winter of 2009/10, it is likely that we will have to wait rather longer to see butterflies and moths on the wing this year than in recent years when spring phenology has been advanced.

Here are some stats on the winter. The Met Office areal series for Scotland which goes back to 1914 has 2009/10 as the second coldest winter on record being only  0.1 C warmer than 1962/63 with a mean winter temperature of 0.3 C.

There are some temperature data for sites in Scotland which go back much further than 1914 and the longest series is for Edinburgh going back to 1764 which was compiled by Robert Mossman.  He created a record for Edinburgh for the peroid 1764-1896 by assembling several datasets recorded in the Edinburgh area. This Edinburgh temperature record can be continued up to date using the Edinburgh Observatory record up to 1960, the Edinburgh Airport data from 1961 to 1999 and data from Leuchars, Fife from 2000.

Here is a graph showing this temperature record back to winter 1764/1765.

Mean winter temperature at Edinburgh 1765-2010

And here are the rankings:

Using data for Leuchars which is outside Edinburgh, the mean winter temp  for 2009/10 was 1.6 C giving a ranking of 10th equal with 14 colder winters since records began in 1765.

I did find data for Edinburgh Gogorbank online back to 2003 but as the Airport closed in 1999, use of this site which is better in terms of siting than Leuchars in the graph above would leave a gap.

But I compare Leuchars and Edinburgh data for winter 2009/10 below:

                         Dec         Jan              Feb

Leuchars           1.2          1.9               1.8
Gogarbank         1.8          1.8              1.9

So Leuchars was 0.6 C colder in December 2009 than Edinburgh Gogarbank meaning winter 2009/10 was 0.2 C warmer at Gogarbank than Leuchars with a mean of 1.8 C.  This changes ranking from 10th equal coldest to 12th equal coldest since 1765.

So winter 2009/10 in Scotland was around 10th to 12th coldest in the last 245 years, so exceptionally cold. The low temperatures of this  winter will certainly have an impact on spring phenology but this effect could be counteracted if spring temperatures are above average. On the date this post was written (21 March 2010), March temperatures are running circa 1 C below average, so late spring phenology is still expected. The winters of both 1979 and 1982 were similarly cold so spring phenology comparable to those two years can be expected.

Some effects are already in evident in Glasgow with daffoldils still not out (they won’t be long!) and crocuses in full bloom. Frogs spawn which normally appears in the first week of March has only appeared a week ago.

So how might butterflies be affected?  As of 21 March, the sightings page for 2010  shows first records for three species: Red Admiral 9 February; Peacock 7 March; and Small Tortoiseshell 12 March. These three species overwinter as adults so can be active as soon as a warm spring day appears. However, the Red Admiral is a migrant species which is considered unable to overwinter in the UK as the winters are too cold for it.  So this is a surprising record given the severity of the winter but it is thought that some individuals have successfully overwintered in southern England in recent milder winters.

The extent to which the spring phenology of our butterflies and moths will be affected this year depends on how they overwinter. The different overwintering strategies are detailed in this blog article. As shown in the paragraph above, species which overwinter as adults are least affected provided that they can withstand low temperatures. Those that overwinter in the pupa/chrysalis stage are also able to respond quite quickly to spring warmth but are likely to be delayed somewhat this year. The Orange Tip and the other Whites overwinter as pupae and are on the wing early in the spring but might be delayed a week or two this year.

For those species which overwinter in the egg or larval stage, the cold winter is likely to have a larger effect as the caterpillars must feed on plant leaves to continue their development. And the much lower soil temperatures which will be present this spring will certainly delay spring growth and bud-burst by several weeks. So the caterpillars which have survived the winter will have to remain hungry until the leaves on which they feed appear and for those which overwinter as an egg, egg hatch will be timed to co-incide with bud-burst, and this will simply be delayed. But the effect of this will be that butterflies and moths which overwinter as larvae or eggs will have their development delayed so their appearance as adults later in the year will be delayed.

So some of the  Fitillaries, Browns, Skippers and Blues could be delayed by up to several weeks this year. So we will all have to be more patient than usual! But it will be interesting to see how long each species is delayed and whether or not there are other effects. We might well see a dramatic drop in Peacock numbers in highland Scotland where temperatures have been very low as adults are not considered frost-tolerant but other species may increase in number if winter predation has been reduced by the cold winter.  By doing butterfly and moth recording this year, valuable data will be obtained which will greatly increase our undertanding on what effect cold winters have on a particular species. So please get and out and about recording!

Written by Andrew Masterman

Forester (Adscita statices) is one of the Burnet moths but does not have any crimson  spots on an inky blue/black background which are charcteristic of this group of spectacular moths. The Forester has green and very shiny wings making it unmistakeable and a very attractive moth to find.

Forester moth Credit: Andrew Masterman

The habitat of the Forester in Scotland is considered to be damp meadows and coastal marshes with a medium to tall sward which contain the larval foodplants, Common Sorrel and Sheep Sorrel, and its preferred nectaring plants which are Ragged Robin, Marsh Thistle and Devil’s Bit Scabious.  Light grazing to control scrub is considered essential but overgrazing is detrimental. Some shelter provided by trees or bracken may also be required but more data on sites in which it occurs would increase our knowledge of its ecology and help to conserve it.

The Forester is on the wing from early June in warm years through July with a few individuals flying in early August. It is a day flying moth being active in sunshine but may be found resting on vegetation in cloudy weather.

The Forester has a well-distributed but local distribution in England but is in decline as the open semi-natural habitats which it inhabits are being lost to agricultural intensification.

In Scotland, the Forester is confined to coastal parts of Argyll and the nearby islands of Jura, Lismore and Mull. But there are some old records from the Borders so it is likely that it used to be more widespread in Scotland but has been lost due to agricultural intensification.

There are 20 Forester records on the west coast of Argyll. It is very likely that the Forester is under-recorded so searching for it in coastal areas between the 20 known sites may well lead to the discovery of new sites.  There are records for the isle of Seil, so it is possible that both Kerrera and Luing also have the Forester. Other promising areas to search for the Forester would be the Ardfern peninsular and the Loch Melfort area.

You can download a Word document containing the three maps below and the grid references by clicking here.

Forester sites on the west coast of Argyll

The map below (click for larger image) shows a close up view of the more northerly sites in the above map.

Forester sites near Oban

The map below (click for larger image) shows a close up view of the more southerly sites near Kilmartin.

Forester sites near Kilmartin

Written by Andrew Masterman