Heathland as we know it only occurs in North west Europe and is one of our most threatened habitats, other types of heath do occur in North america ,Canada, Russia, Scandinavia, South Africa and Australia. It is well known that heathland is a predominately man made habitat, it has been manipulated by humans in some way going back over 5000 years with most heaths having traces of human use, with a little help later from rabbits and sheep of course! Beginning with the gradual clearing of our forests resulting in the soil becoming impoverished, creating the right environment for the development of a 'dwarf shrub community' which man continued to exploit and make use of its resources shaping it into heathland as we know it. Unfortunately there isn't much lowland and coastal heath left in the UK now with c 80% of it lost since the 19th century, due to either over use or abandonment by man, highlighting the importance of managing whats left for the wonderful diverse species that made it their home.
As with all habitats comes a host of specialised species which found their niche,the specific requirements to complete their life cycle. Although the management we do is about the overall health and biodiversity of the heathland ecosystem, we do some small scale management to continue to create and maintain the right conditions for some rarer species. The silver studded blue butterfly is one such species which benefits from the work we do. A coastal species which has seen major declines and now has a restricted distribution but can still occur in large numbers in suitable coastal heathland and grassland habitats. South Stack proudly is one of their strongholds in North Wales. It is one of my favourite wildlife sights when they emerge, watching clouds of them dancing and skipping low across the heath. They are smaller and daintier than the common blue, which are stronger higher flyers, they have at least 2 broods and can be seen flying between late May and October. The silver studded blue generally have one brood. I don't recall ever seeing a second brood here at South Stack but know they do at some sites. They can be seen flying here generally from late June/early July until early August, I notice the overlap with the silver studded blues flying between the 2 broods of the common blue. So not a very long flight period of about 5-6 weeks and these little beauties have to get busy! A little fussy and picky about where they live, if the habitat isn't suitable a colony will simply die out. The majority do not travel very far with most adults not moving much more than 20 metres in a day, so they can struggle to spread and recolonise if suitable habitat isn't available locally although a small number will disperse further.
These butterflies although small are a bit demanding! They like a mixture of bare ground, short and longer vegetation for breeding and shelter. They rely on the pioneer/regenerating stage of a heathland for a number of reasons throughout their life cycle. This is largely connected to their fascinating relationship with ants. Female silver studded blues will only lay their eggs where they can detect suitable ant pheromones. The bare ground/early regrowth stage creates the right conditions and encourages good populations of ants. She will lay her eggs singly on the stems of short vegetation where they will stay over winter and hatching in the spring to feed on their food plants. It is thought the ants carry the larvae into their chambers or under nearby stones and look after them while the pupate and emerge as adults, it is believed the larvae produce a sugary substance attractive to the ants so a good deal it seems! Therefore regular disturbance of small patches is needed to create this mosaic of age structure and is what I have been aiming to create at a struggling colony not far from the Ellin's tower car park.
There is a small colony of silver studded blues which are relatively far from the other colonies on the reserve, so a tricky one to be recolonised for these not very intrepid travelers! So small scale management really could save this small colony. Over the last 5 years I have cut a series of strips through the maritime heath. Leaving at least twice as much mature uncut heather in between them, eventually every 8 or so years I can rotate the cutting so there will be this continuing state of succession and regeneration to mature. The results are visually pleasing too, by breaking up the closed canopy, allowing the light too reach the ground enables the dormant seed bank of flowering plants to carpet the plots from their second spring, as you can see in the pictures. They are lightly grazed in the autumn by our lovely flock of hebridean sheep which help to slow down the regenerating stage. Also providing dung which encourages the invertebrates and benefit chough. These cleared areas are of great value to such a wide variety of wildlife, a particular favourite of mine is watching skylarks and meadow pipits. Seeing them hunting on the ground on them especially in early spring when flocks are moving around, also the almost guaranteed sighting of a dotterel stopping over each spring and autumn migration on the short cleared areas for well needed rest and refuelling! They also provide hunting/basking areas for reptiles and ground hunting invertebrates such as beetles as well as providing food for butterflies, moths, bees etc. Eventually the canopy will close over again reaching a mature age before being cut again within the rotation cycle.
I will update you on how they are doing this year and include some pictures of them once they are flying, they roost in groups in tall grasses which is always lovely to see, meanwhile this little corner on the cliff is good to go and is 5 star silver stud digs! Stay safe everyone love and good health to you all x
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