Glasgow & SW Scotland Butterflies

Glasgow & SW Scotland Branch Website

January 16, 2010

New edition of ‘On the Spot’ out now!

The new 25th anniversary edition of On the Spot, the newsletter of the Glasgow & South West Scotland branch of Butterfly Conservation is out now!

On the Spot January 2010

On the Spot January 2010

Glasgow & SW Scotland branch members should get their copy in the next day or so, in time for the 25th anniversary of the founding of the branch on the 19th of January!

Scott Shanks (Newsletter Editor)

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.

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