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Butterfly Conservation- Glasgow & South West Scotland Branch


Northern Brown Argus Surveys 2011

Introduction

The Northern Brown Argus is a UKBAP high Priority Species and is one of 6 butterfly species included on the Scottish Biodiversity List. As its name suggests the Northern Brown Argus is found in the North of Britain, predominantly in Scotland. In the north of England populations have shown a significant decline during the last decade, with extinctions recorded at sites that previously supported strong colonies. At the present we have very little information concerning the status of this important species in South West Scotland.

A number of sites have been identified where the butterfly was recorded in the past (see table below). In order to determine whether colonies still exist at these sites further visits and habitat assessments are required. It is hoped that data collected in this survey can be used to establish suitable conservation strategies to protect this charming little butterfly.

Credit: Norman Tait
Credit: Norman Tait
Credit: Scott Shanks

Methodology

If you see any Northern Brown Argus, it would be appreciated if you could complete a NBA survey form which records habitat characteristics including the abundance of larval food plants and nectar species, whether bracken or scrub is invading the site, as well as numbers of butterflies. And of course, record any other butterflies that you come across.

There is some data to suggest that the larvae and pupae may be protected from parasitic wasps and predators by ants, so it would be interesting to note if ants are recorded on or near caterpillar food plants or interacting with larvae.

Photographs and /or a sketch of the site showing where you searched and features of interest would be fantastic.

  • Ideally take a map of the area to be surveyed and a compass/GPS
  • Wear stout footwear such as walking boots, and a hat and sun block are recommended in sunny weather
  • Take something to drink and a snack or packed lunch to enjoy while out in the sunshine.

Description & Ecology

The Northern Brown Argus is a charming little butterfly with dark slate-brown wings (26-35 mm wingspan) edged by red-orange lunuals (crescent shapes), and either a white or black spot in the middle of the forewing upper surface. There are two distinct subspecies of the butterfly in Britain: In the North of England the salmacis ssp has a black spot on the upper-side of the forewing, while the Scottish artaxerxes ssp has a characteristic white spot. Both sexes of the Northern Brown Argus are similar in appearance, with the female having a greater number of red lunuals edging the upper forewing. The underside of their wings are pale gray-brown with many white spots and a few black dots, similar to those of the common blue. The name argus comes from the 100-eyed giant of Greek myth and relates to the many spots on the under-wing. In flight they can appear silvery brown as they flit from flower to flower.

Credit: Scott Shanks
Credit: Martin Warren
Credit: Jim Asher

After emerging in late May/early June, the adults set about finding mates with much nectaring and basking in the sun too. The adults within a colony tend to be quite sedentary, moving only 20-30 m over the course of a few days, but occasional adventurous individuals may wander as far as 150 m looking for mates or a suitable site for laying eggs.

Colonies tend to exist on south facing ungrazed or lightly grazed slopes with abundant larval food plants and lots of nectar plants such as thyme and bird’s-foot trefoil. Sites often have bare ground resulting from grazing, landslips, footpaths or rocky out-croppings.

The disc-shaped pale blue-green eggs are laid on the upper-surface of the leaves of common rock-rose (Helianthemum nummularium), the main larval food plant. It is thought that in South West Scotland, females may also use members of the geranium family such as bloody cranesbill (Geranium sanguineum), dove’s-foot cranesbill (Geranium molle) or common storksbill (Erodium cicutarium) as larval food plants

Eggs hatch between 6 and 15 days after being laid, depending on temperature and weather conditions. After hatching, the small green woodlouse-like caterpillars move to the underside of the leaves to feed. The caterpillars produce distinctive ‘windows’ on the underside of the leaf as they feed, leaving the upper side intact. Only one generation is produced per year, and after feeding until October the 2nd or early 3rd instar caterpillar goes down into the leaf litter to hibernate.

In April the caterpillar resumes feeding and basking in the Sun once more. After hibernation/ diapause, larvae have been observed being attended by ants that are attracted by pheromone-producing organs on the caterpillar abdomen. The yellow meadow ant Lasius flavus and the black wood ant Formica lemani have both been observed tending post-diapause caterpillars. This relationship with ants may help protect the larvae from parasitoids such as the ichneumonid wasp Hyposoter notatus that may parasitize up to 67 % of larvae at some sites. When fully grown (~12 mm), the caterpillar forms a green-brown pupa either on a silken mat on the ground or attached to low vegetation by silk threads. The pupa is 8-9 mm in length. The adults generally emerge after about 3 weeks.

When To Do

The flight period of the Northern Brown Argus in South West Scotland can vary considerably due to temperature and weather conditions in the spring. Adults may be on the wing from the end of May through to mid- August, with a peak in numbers from mid-June to the end of July. In 2007 and 2008 the first sightings of the year were on the 26th and 28th of May respectively.

The best dates for this survey are from the 4th of June through to the 25th of July, but a week earlier or later may also prove fruitful. If possible warm sunny days should be chosen for the survey when adults will be most active. In overcast conditions adults may be found roosting on grass stems in a head-down position. On dull days it may still possible survey habitat at the sites and to look for eggs and young larvae. Sites may also be visited in April to look for post-diapause larvae and possibly witness ants in attendance.

Taking photographs of sites with a digital camera is a great way of providing information on the state of a site. A photograph must be linked to a grid reference, site and date, so please record these data in a long descriptive file name and


Sites in Ayrshire and Dumfries & Galloway to be surveyed for Northern Brown Argus

The map below shows the 21 sites requiring visits in June/July 2011. If you place your mouse over the site name, a little window with the site name will appear and if you click on the site name, a 2 x 2km OS map will appear in a new window. Click here for a Word document containing the map and table below which you can print out and take out into the field.



Site Name
Description
Grid Reference
(Click for OS map)

Pinbain Burn, Lendalfoot

Steep flower-rich hillside on basic rock next to burn and coastal path north to Kennedy's pass. Park at layby on A77 north of Lendalfoot. OS Maps 76 or 317

NX138916

Knockdolian Hill

South and west face of hill near Ballantrae.Look for “Stinchar Valley Trails” signpost on the B7044 about 3 miles from Ballantrae. May be possible to park on verge near Knockdolian castle. OS Maps 76 or 317

NX110847

Bennane Head, Ballantrae

Bennane Lea to Balcreuchan Port. Steep coastal path, undercliff and coastal grassland. Park on old A77 at NX092859. OS Maps 76 or 317

NX091868

Currarie Port,South Ayrshire

Herb-rich grassland on basic rocks and gully with oaks. Park at side of farm track at NX063770. OS Maps 76 or 317

NX110847

Finnarts Hill to Portandea

Coastal grassland and hillside from Finnarts Bay up to Portandea. Carpark in Finnarts Bay off the A77 at NX052726. OS Maps 76 or 309/317

NX052752

Portpatrick

Coastal path (Part of Southern Upland Way) from Port Kale/Port Mora down to Morroch Bay. Park at Portpatrick. OS Maps 82 or 309.

NW995544

Port Logan Bay

Coastal habitat: sandy shore and rocky grasslands. Carpark on B7065 at NX096411. OS Maps 82 or 309

NX096412

Kirkmaiden, Monreith

Rocky coastal habitat on Monreith Bay. Carpark at NX365394. OS Maps 83 and 311

NX267503

Garheugh Port,Luce Bay

Coastal habitat. Rocky shore and grasslands. Park at Picnic site on A747 at NX255513. OS Maps 82 or 310

NX365397

Port Castle Bay to Fell of Carlton

Coastal habitat and cliffs. Park in Kidsdale (near St Ninians Cave) at NX432366. OS Map 83 or 311

NX398372

Ravenshall,Gatehouse of Fleet

Coastal cliffs and habitat from Ravenshall Point to Ravenshall Wood. OS Maps 83 or 312

NX521525

Carrick, Gatehouse of Fleet

Rocky Coastal habitat arround Carrick, facing Fleet Bay and the Islands of Fleet. OS Maps 84 and 312

NX576504

Brighouse Bay

Rocky shoreline and woodland around Bighouse Bay from Dunrod Point on west side to Mull Point on west side. Carpark at top of Bay at NX634457. OS Maps 84 and 312

NX628447

Burrow Head, Isle of Whithorn

Coastal cliffs and grassland. Pathway from Isle of Whithorn down to Burrow Head. Parking at Isle of Whithorn NX479361. OS Maps 83 and 311

NX448343

Rascarrel Bay

Coastal footpath from Balcary Bay to Rascarrel Bay. Park at NX820494. OS Maps 84 or 313

NX827493

Rockcliffe to Portling

Coastal walk from Rockcliffe to Castle hill Point. Scenic footpath carries on towards Portling. Good habitat along here. Park off Colvend to Rockcliffe Rd at NX851535. OS Maps 84 and 313

NX854526

Auchenfad Hill, Mabie Forest

Conifer plantation hillside with forestry Road. Park either at Mabie Forest carpark at NX949711 or possibly on Forest track. OS Maps 84 or 313

NX950696

Lochanhead, Mabie Forest

Dismantled Railway and south facing embankments North of Mabie Forest. Carpark at Woodfoot Wood at NX929370. OS Map 84 or 313

NX915717

Stroan Loch

Grasslands and paths near Stroan Viaduct and Loch. Park at picnick site NX649700 or Mossdale NX660705.OS Maps 77 or 320

NX644701

Carsfad Loch

Records from south and east sides of Carsfad Loch. From just north of Nether Cleugh Farm southwards to area around Power station at South of Loch. Parking at Dundeugh at NX601881 or on verge. OS Maps 77 or 328

NX612865

Polmaddie

An abandoned farming settlement in Galloway Forest, Parking at NX592877 or at Dundeugh at NX601881. OS Maps 77 or 328

NX590880



Written by Scott Shanks

References

  • Futter, K., Sutcliffe, R., Welham, D., Welham, A., Rostron, A., MacKay, J., Gregory, N., McCleary, J., Tait, T., Black, J. & Kirkland, P. 2006. Butterflies of South West Scotland. Argyll Publishing. (see Atlas page)
  • Asher, J., Warren, M, Fox, R., Harding, P., Jeffcoate, G., Jeffcoate, S. 2001. The Millennium Atlas of Butterflies in Britain & Ireland. Oxford University Press.
  • Fox, R., Asher, J., Brereton, T., Roy, D., Warren, M. 2006. The State of Butterflies in Britain and Ireland. Pisces Publications.
  • Tomlinson, D. & Still, R. 2002. Britain’s Butterflies. WILDGuides
  • Ravenscroft, N. O.M and Warren, M. S. 2001. Northern Brown Argus Aricia artaxerxes species action plan. Butterfly Conservation

 
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