Glasgow & SW Scotland Butterflies

Glasgow & SW Scotland Branch Website

January 8, 2009

Wider Countryside Butterfly Survey

Filed under: Butterflies — Andrew Masterman @ 11:07 pm

For many years, Butterfly Conservation has been aware that many “common” butterfly species have undergone serious declines and are also in need of conservation action.  However, Butterfly Conservation’s current butterfly monitoring and recording schemes do not provide enough information to pick up detailed trends in the countryside as a whole. The UK Butterfly Monitoring Scheme (UKBMS) mainly covers semi-natural habitats and the Butterflies for the New Millennium scheme (BNM) gathers crude measures of abundance from opportunistic visits rather than from a systematic survey. In both these butterfly recording schemes, “ordinary” farmland and upland areas are greatly under-surveyed. The new Wider Countryside Butterfly Survey (WCBS) is intended to fill these gaps and will give Butterfly Conservation estimates of the abundance of widespread butterflies in the countryside as a whole, as well as adding to distribution data.

The Wider Countryside Butterfly Survey aims to achieve the following:

1)    To identify trends of widespread butterflies in the countryside so that Butterfly Conservation can lobby for more effective conservation of the landscape as a whole.

2)    To identify richer areas of the countryside for different widespread species.  This would help Butterfly Conservation relate density to landscape features and enable us to influence new landscape conservation measures.

3)    To evaluate the impact of Government “green” farming schemes (such as Environmental Stewardship in England) and see whether such schemes are helping species such as the Small Copper and Common Blue.

4)    The data will give Butterfly Conservation  another valuable dataset to help monitor climate change. 

 The Wider Countryside Butterfly Survey is based on the Breeding Bird Survey methodology of the British Trust for Ornithology in which randomly selected 1 km squares are visited twice during the breeding season to determine which bird species breed in the 1 km square.

The Wider Countryside Butterfly Survey has been field-tested over the last three years by several branches and the feedback has been very positive. Butterfly Conservation hopes that each branch will manage to survey 20 randomly selected 1 km squares using 2 to 4 visits between May & August.

See Wider Countryside Scheme for further information.

If you would like to volunteer to take on a 1 km square in the Glasgow & SW Scotland Branch area, please see Volunteers Wanted for Wider Countryside Butterfly Survey in 2009.

 
 

 

Posted by Committee Member Andrew Masterman

January 7, 2009

A second brood of the Iron Prominent in the Glasgow area?

Filed under: Moths — Tags: , , , , — Scott Shanks @ 12:34 am

The Iron Prominent (Notodonata dromedarius) is a furry medium-sized moth with distinctively marked dark grey-brown forewings with rusty-brown streaks.  According to Waring & Townsend, the species is widely distributed throughout the UK, however the distribution map on the NBN gateway site suggests it’s largely absent from south west Scotland. Individuals in northern England and Scotland often have a darker ground-colour with fainter markings.

Iron Prominent on my thumb

Iron Prominent on my thumb

In the south of Britain there are usually 2 generations per year, with adults flying in May-June and late July-August, while in the north of Britain and Ireland there is a single generation each year with adults flying June-July…at least that’s what it says in the books!

While trapping at SWT Loch Ardinning (Just north of Glasgow) on the 30th of August 2008 I had an Iron prominent come to the light of my 15W actinic heath trap. (NS569777 ). It was a feisty wee thing and took ages to settle down, causing total havoc as it disturbed the other moths in the trap. I think that’s why one of its wings looks so badly worn.

Iron Prominent moth

Iron Prominent moth

 

 I passed this record to John Knowler the vice county moth recorder for Stirlingshire, who replied had he’d also had a late Iron prominent come to light.  It looks like the Iron prominent may have had a partial second brood in Scotland during 2008.

Could this be a response to global warming? According to BBC weather records for 2008, temperature records in Scotland were a degree or two above average during both July and August. It was also wetter than usual once more! Could it be that this small increase in temperature is enough to trigger a biochemical response in larvae or pupae that aborts the usual ‘hibernate’ signal, and leads to accelerated development of larvae or early emergence?  

The Iron prominent can be found in broadleaved woodlands, heaths, wet carr, riverbanks and occasionally gardens. The pale green caterpillar has a brown stripe along its back, with humps on the 4th-7th and 11th segments of its body. It can be found feeding on birch and alder, and occasionally hazel or oak. The Iron prominent overwinters as a pupa in a flimsy cocoon under the soil. Supposedly the caterpillar is quite easy to raise in captivity if supplied with fresh vegetation every few days, but should probably be returned to the wild before it pupates to maximise the chance of the adult’s emergence coinciding with a suitable mate the following year.

Certain montane invertebrate species can exhibit delayed larval development in cold and wet years, which prevents the population being wiped out if the adults emerge during inclement conditions and fail to breed. The ability to produce additional generations when conditions are good may be another aspect of this phenomenon?

Does anyone else have other ‘late’ records of the Iron prominent in Scotland? Was this a local event or was it nationwide? It’s likely that other species may be responding to temperature increases in a similar way. Perhaps we could compile a list of species that are taking advantage of climate changes to produce further generations during the year? Such species may prove useful as biological indicators of wider habitat and environmental changes happening around us that we should ‘keep an eye on’ in the future.

Feel free to add any sightings, comments or thoughts below. :)

Scott

January 5, 2009

Conservation of the Dingy Skipper butterfly in South West Scotland

The Dingy Skipper (Erynnis tages) is currently the rarest of the 34 butterfly species found in South West Scotland. The adults are small and well camouflaged with grey and brown wings and can easily be mistaken for a moth. (See Dingy Skipper species information page for more details). In the last few decades it has suffered a severe decline throughout the UK and is now classed as a national BAP priority species.  The reasons for this decline are not entirely clear as the food plant Bird’s-foot trefoil (lotus corniculatus) is pretty widespread, however it appears that female dingy skippers are very selective in where they lay their eggs!

Dingy Skipper on bird's-foot trefoil. Keith Warmington

Dingy Skipper on Birds foot trefoil by Keith Warmington

 

 

 

 

 

Changes in land use, such as agricultural intensification, the cessation of coppicing in woodlands, habitat succession, and the recent policy of developing brownfield sites appear to be major factors in the loss of this species. Adults also tend to be quite sedentary and are unlikely to move to new suitable habitat unless it is very close by. Larger colonies are more likely to produce exploratory individuals that could initiate a new colony.

Ideal habitat conditions occur where bird’s-foot trefoil (or occasionally greater bird’s-foot trefoil) is found in warm sheltered sites with sparse sward/grass covering and plenty of bare patches for basking in the sun. Patches of taller vegetation or light scrub may be used by the adults as roosting sites. In south west Scotland the Dingy Skipper has been recorded at a few sites along the south coast of Dumfries and Galloway; in small numbers on the Ayrshire coast south of Girvin and also at a few inland sites such as the Butterfly conservation reserve at Mabie forest. A colony at the SWT Feoch meadows reserve was only discovered in 2008, and so other potential sites may be awaiting discovery.

It is hoped that further local colonies can be identified and protected before it is too late. In order to conserve the species we first need to know its current distribution and the size of existing colonies. At some sites only one to two individuals have been seen, so it is important to confirm that theses sites contain breeding colonies rather than just vagrants passing through. For detailed conservation planning and action to take place it is important to identify where on these sites the dingy skipper is breeding. Once this is known, the breeding areas can be preserved and hopefully enhanced by appropriate management or habitat creation.

I believe that most of the recent sightings in south west Scotland have been of individuals or small numbers of adults. Does anyone know of large colonies? Are these individuals part of small fragmented colonies, or perhaps vagrants from larger colonies existing undetected nearby? The low number of sighting haven’t been helped by the poor weather conditions we have had during 2007 and 2008 combined with the relatively small number of people who would know what they were looking at if they did see one!

To confirm breeding at a site where adults have been seen it is possible to search for dingy skipper eggs on bird’s-foot trefoil. This is best done after the peak flight period of the adults, and importantly can even be done on overcast days when adults wouldn’t normally be seen. In south west Scotland the peak adult flight period is normally around the first week of June, so eggs will be visible during the following 2 weeks before they hatch. The female lays her eggs singly on the upper surface of leaves on fresh shoots, normally within a 2.5 cm of the shoot tip. Occasionally more than one egg will be found. The eggs are round and greenish-white when first laid and can be quite difficult to see, but later (after about 5 days) turn a bright orange which should be easier to see (unless like me you are red-green colour blind!). The female generally chooses shoots growing away from the main plant especially those spreading over bare ground or rocks. Rocks and bare ground will absorb and hold more warmth than surrounding vegetation, which may enhance development of the egg and larvae. Plants in sheltered hollows will be chosen over exposed plants.

Dingy skipper egg. Keith Warmington

Dingy skipper egg. Keith Warmington

When searching for eggs, look for areas of the site with bird’s-foot trefoil. Walk in rows about 1m apart back and forth, stopping if you find a plant with tendrils growing over bare ground or path. Shoots growing over dry dead fescue grasses (small fine bladed grasses) may also be used, especially if in a dip or hollow. Its only worth searching hollows were the food plant is sheltered, but not shaded by surrounding vegetation. It’s no use searching areas where the vegetation is higher than 15cm. If you find a likely spot, bend forward so your head is parallel with the plant and you will hopefully be able to see an egg. Once you’ve seen one, you should be able to spot others more rapidly. If you find eggs on a plant in a hollow or bare patch, search others nearby as other females may also have taken a fancy that location. The caterpillar is green with a dark green stripe down its back and a dark head. They tend to be more difficult to see as they form a tent of leaves and silk to hide in.

Any records of adults, eggs and the rather shy green larvae would be very welcome (butterfly records page). If you can get a photograph of the site and particularly the location where eggs were seen, or even just a description, this could proved very valuable information for the protection of the site and the conservation of this endangered species. It would be useful to know if any adults were seen at the site, if multiple eggs were found on the same plant, the colour of the eggs (indicating how recently they had been laid), the height of surrounding vegetation, were there any signs that the site was grazed (cow pats? Tufts of wool? Rampaging bulls?) or maintained by mowing?.

Much of the egg hunting advice above was taken from a fantastic article by Mike Slater in the February 2008 edition of the Warwickshire butterfly conservation newsletter.

I hope this is useful information for anyone who’d like to get out and search for this charming and often overlooked little butterfly. Please feel free to leave a comment below, or information on any of your sightings and locations.

Written by Scott Shanks.

January 4, 2009

Alder Moth (Acronicta alni)

Filed under: Moths — Andrew Masterman @ 12:47 pm

The Alder Moth (Acronicta alni) is a medium sized greyish noctuid  with areas of darker markings which are diagnostic.

The Alder Moth is found in broadleaved woodland and scrub, often on poorly drained ground. The NBN Gateway shows its distribution to be confined to England & Wales where is is thinly distributed and local but Waring & Townsend does state that it is recorded from SW Scotland.

Recent records of Alder Moth in SW Scotland are:

  • 1 adult 17 May 2008 at Taynish NNR (Andrew Masterman)
  • 1 adult 28 June 2008 at RSPB Lochwinnoch (Paula Baker)
  • larval record 26 August 2007 at RSPB Lochwinnoch (Paula Baker)
  • 1 adult 3 June 2007 at Isle of Bute.

The Alder Moth doesn’t just feed on Alder but also on other broadleaved trees too including Downy birch, Goat Willow, Oaks & Elms.

Given its distribution being confined to a few sites in SW Scotland and the ubiquitousness of its foodplants, the Alder Moth is a species which is likely to have been expanding its range due to climate warming in recent decades so any new records elswhere in Scotland would be interesting. If you have any Scottish Alder moth records, please add them to this post in a comment below.

Posted by Committee Member, Andrew Masterman

Alder Moth (Acronicta alni)

Alder Moth (Acronicta alni)

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