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Butterfly Conservation- Glasgow & South West Scotland Branch

Pearl-bordered Fritillary surveys in Loch Lomond and the Trossachs 2011

UPDATE 9 May 2011: the good news is that Pearl-bordered Fritillary was found on the 1 May just outside the boundary of the Loch Lomond and Trossachs National park just west of Killin in square NN5634. It has also been recorded a bit further west a few years ago (NN5435). There is quite a lot of south-facing hillside here which needs to be explored for PBF habitat. The presence of PBF here would suggest that it may be present further west along Glen Lochay and also a bit further south on the north side of Glen Dochart which also has extensive south-facing bracken hillside. With respect to Loch Lomond, Rubha Mor, Firkin Point and Ardvorlich were visited on the 4 May in good weather and no PBF were seen and only small pockets of suitable habitat were found. So PBF is definitely not present at any of these sites and is unlikely to be present at any of the other potential sites around west Loch Lomond.

The Pearl-bordered Fritillary Boloria euphrosyne has been described as the 'lost butterfly' of Loch Lomond and the Trossachs as it used to be known at a few localities but recent observations are few. One of these localities was the north side of Loch Katrine where it had been seen in the 1980s and 1990s. Efforts to find the Pearl-bordered Fritillary at Loch Katrine in 2008 were unsuccessful as were those in Duke's Pass in an area with suitable habitat. However, it is possible that some of the many 1 km squares further west along the north side of Loch Katrine may have Pearl-bordered Fritillary. The best way of surveying these would be on a bicycle (these can be hired at Loch Katrine) and then walk up through the woods to open hillside above the trees at 200-300 m where steep dry open hillside with dog violet may provide suitable habitat.

A brief visit to Beinn Narnain was also made in 2008 with no success but dog violet was present so also worth another look. The only site along the west side of Loch Lomond checked out in 2008 was Glen Falloch on two occasions and no Pearl-bordered Fritillary were seen: the sites further south still need to be checked out.

It is probably the case that the chances of finding Pearl-bordered Fritillary along Loch Lomond are not high, so if want to visit sites where you are very likely to see Pearl-bordered Fritillary, choose the Loch Tummel Pearl-bordered Fritillary Network or other Pearl-bordered Fritillary sites in Scotland.

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When to Do

Volunteer surveys should be done during mid to late May 2011. Any individuals seen between 21 May and early June may be either Pearl-bordered or Small Pearl-bordered, hence earlier survey dates are preferred but visits in this period may be undertaken if poor weather or circumstances prevent an earlier visit. These butterflies are easy to spot as both species are bright orange and any seen prior to 21 May are very likely to be Pearl-bordered Fritillary.

Methodology

The relevant OS map for the site you want to survey will be required to do this survey. All these sites are quite close to main roads and therefore do not require a long walk in but these south-facing hillsides are steep so a moderate level of fitness is required to ascend up to 250 m or so. Stout walking boots are recommended.

If you see any Fritillaries, it would be appreciated if you could complete a Pearl-Bordered Fritillary Timed Count Sheet which records some details of habitat characteristics such as abundance of Dog Violet & Bugle as well as numbers of butterflies. And of course, record any other butterflies that you come across.

But if you prefer to send in more limited data by email, then please with basic information including 6 figure OS map reference, date and counts of Fritillaries.

The ideal way of recording Pearl-bordered Fritillary numbers and distribution is with a GPS device. There are some relatively inexpensive models available eg Garmin eTrex Venture is 122.20 from Amazon.co.uk and can store the positions of up to 500 butterflies with Waymarks. Data is then downloaded onto a computer using software provided with the GPS device.

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 Loch Lomond and the Trossachs to be surveyed for Pearl-bordered Fritillary

The map below shows the 9 sites requiring visits in May 2011 - not Glen Ogle which has been searched and Pearl-bordered Fritillary not found despite suitable habitat. 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.



Site Name
Grid Reference
(Click for OS map)
Description

Rubha Mor, West Loch Lomond

NS343998

Bracken hillside above steep road escarpment with crawler lane - park at layby to the south of crawler lane, access via style at south end of layby

Firkin Point, West Loch Lomond

NN331011

South-facing bracken hillside in sw corner of NN3301 - park at Firkin Point

Glen Croe, Ardgarten, West Loch Lomond

NN256043

S facing slopes of The Cobbler in Ardgarten Forest - park at Ardgarten Visitor Centre

Beinn Narnain, West Loch Lomond

NN285053

S facing slopes of Beinn Narnain above forestry plantation - park at Loch Long car park

Inveruglas, West Loch Lomond

NN305092

S facing slopes of Ben Vorlich along track up to Loch Sloy - park at Inveruglas viewpoint

Creag an Arnain, West Loch Lomond

NN324108

South-facing slopes above viaduct just north of Inveruglas. Park at Inveruglas or at rough layby close to viaduct.

Ardvorlich, West Loch Lomond

NN324122

100m little hill with S facing hillside just west of railway.

Ardlui, West Loch Lomond

NN315158

SE facing bracken hillside just north of Ardlui - park beside rd at Ardlui station

Loch Katrine, Trossachs

NN4410

Square NN4610 and further east have been checked but squares NN4410, NN4310 & NN4210 have steep-south facing hillsides and could have suitable habitat.



Key:

not yet assessed as suitable habitat


 
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