Lake Vyrnwy

Lake Vyrnwy

Lake Vyrnwy
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Lake Vyrnwy

  • A First for Wales?

    Overall, this week has been fairly mundane with a couple of rainy days working in the office and the rest of the week removing invasive non-native plants (see Plant of the Week below).

    However, on a sunny Wednesday morning a few of us got the opportunity to join the Wales Reserve Ecologist, Gareth Fisher, for a bit of Welsh Clearwing moth surveying. We surveyed known clearwing areas to see if any were emerging and to decide what management would be required to improve the habitat. Welsh Clearwing larvae feed in mature birch trees with the larvae burrowing through the bark and feeding inside until ready to emerge. They are usually found up to 2m from the base of the tree where they are more likely to be exposed to the sun. There were a good number of promising looking trees and a few exuvia (casing of emerged insects) indicating some adults had emerged recently.

    Welsh Clearwing exuvia (Photo by Gavin Chambers)

    While looking very closely at the bark of one Birch I noticed a small micro moth tucked in to a crevice. Having flicked through the micro moth book numerous times this one didn’t spring to mind. Fortunately Gethin had a camera with a decent macro setting and managed to get a reasonable, OK... very good, image of it given its size of 7mm in length.

    Denisia similella (Photo by Gethin Elias)

    Once back at home I immediately got the micro-moth book out and found what appeared to match the image. The description also mentioned the fact that the larvae feed on types of fungus, which can be found on old dying Birch. However its range/distribution was classed as being a northern species most commonly found in Scotland and the map showed Herefordshire as being the closest county to have a record with a scattering of records in northern England. So had we found a first for Wales?!?! A quick email to Montgomeryshire County Moth Recorder, Peter Williams, revealed that it is certainly a Denisia similella the first for North Wales and almost certainly a first for Wales!!!! Just goes to show what is still to be found, you've just got to look!

    An unlikely birding highlight this week was a group of 7 Collared Doves in the village of Abertridwr which are annual but for some reason rarely seen. The pair of Great Crested Grebes have built a new nest at the top of the lake and a Little Grebe has also been seen feeding from the Lakeside hide.


    Plant of the Week

    Himalayan Balsam / Ffromlys chwarennog (Impatiens glandulifera) (Photo by Gavin Chambers)

    Himalayan Balsam was introduced to the UK in 1839 and is now found across the majority of the country. It is commonly found along riverbanks and in wastelands where it has become a very problematic weed. It does not require much light to grow and once fully grown it can reach heights of 2-3m and smother other plants of light and nutrients which eventually kills them off.

    In late summer it produces clusters of purplish pink flowers, helmet-shaped. These are then followed by seed pods which is where the problems start. Each plant can produce up to 800 seeds and it has a coiled spring mechanism, which can fire seedpods up to 7m away once ripe and mean a rapid spread. To add to this seeds can stay viable for 2 years and due to their typical riverbank location, the seeds can be transported downstream and deposited on a new bank to start a new colony.

    This week we have started to remove as much Balsam as quickly as possible before they start seeding. Our method, which is the best non-chemical method of control, is to pull the individual plants out. This works because it is an annual plant, meaning it only lives for a single summer then dies and will only grow back from seed.

    Previous Blog: Blue Dragons!

  • Blue Dragons!

    Though we a situated in the heartland of the Red Dragon, it has been the Blue Dragons that have been most prominent these last couple of weeks. The soaring temperature, reaching around 25°C, gave dragonflies and butterflies the chance to warm up and emerge from their nymphs and chrysalises.

    So one sunny afternoon I decided to get the weekly Butterfly Transect done which, with the temperature at 23°C, promised great things. The first few sectors were very quiet with only a Large Skipper and Meadow Brown being recorded and moths in the form of Beautiful Carpet, Wood Tiger and Clouded Buff being nice additions.

    Wood Tiger along Butterfly Transect (Photo by Gavin Chambers)

    The end of the transect picked up with a good variety of Butterfly seen but not really in the numbers you might expect in the conditions. A nice patch of Forget-me-knot had attracted a Green Hairstreak and a rather worn Common Blue which isn’t as common at Lake Vyrnwy as its name suggests. Other species seen were: Ringlet, Small Copper, Small Pearl-bordered Fritillary, Green-veined White, Small Tortoiseshell and Small Heath. So 11 species recorded but only 14 individuals in total perhaps suggesting the cold spring in to summer has affected them or there are still many more to emerge.

    Male Broad-bodied Chaser at Lake Vyrnwy (Photo by Gavin Chambers)

    So the Blue Dragons.... at the end of the transect there is a small dammed pool with small stream running in and out of it. It is great for Dragonflies and Damselflies and this was certainly true in the blazing sunshine. The usual suspects were around: Common Blue, Azure, Blue-tailed and Large Red Damselflies and Four-spotted Chasers. There was then a few flashes of chalk blue zipping around the edge of the pool, the largest one was fairly easy to get an ID of – a stunning male Broad-bodied Chaser.

    Male Black-tailed Skimmer, a first for Lake Vyrnwy (Photo by Gavin Chambers)

    The other blue flash was smaller and thinner bodied, so would have to be a male Keeled Skimmer or Black-tailed Skimmer. However Black-tailed Skimmers like pools whereas Keeled Skimmers prefer small running ditches and damp areas. It was soon joined by a female which, after the male had sat for a photograph, also helped confirm ID as a pair of Black-tailed Skimmers. It later transpired that this was the first record of this species at RSPB Lake Vyrnwy!

    Beautiful Demoiselle at Lake Vyrnwy (Photo by Gavin Chambers)

    The final species was a real beauty, a stunning iridescent Beautiful Demoiselle which unlike its close relative, the Banded Demoiselle, prefers running streams to slow moving water.

    On the bird front, the summer migrants are starting to disappear from the woodlands. However a summer migrant was heard for the first time this year - a Quail. This tiny gamebird which is recorded here most years has a very distinctive call/song which is said to sound like 'wet-my-lips' which you can listen to here. A Kingfisher has also been seen off the dam, as were a group of 9 Common Sandpipers roosting on the shoreline and are probably a group on migration south.

    Plant of the Week

    Greater Butterfly Orchid / Tegeirian llydanwyrdd (Platanthera chlorantha) (Photo by Gethin Elias)

    Last week Gethin Elias re-discovered this plant growing on the reserve it hasn’t been recorded since 1986.

    An orchid of hay meadows and grassland it can be found along rides, clearings and edges of woodland. Due to the massive decline in meadows in the country this orchid is struggling to survive and has unsurprisingly greatly dropped in numbers.

    A single spiked plant up to 60cm in height, it has several whitish to green flowers each with spread sepals and petals. The flowers lowest petal is yellowish green and long and narrow with its leaves being spotless, broad, shiny and elliptical. Care should be taken to separate the Greater Butterfly Orchid with its close relation the Lesser Butterfly Orchid, you need to examine the pollinia (mass of pollen)!

    Previous Blog: Future Secured!


  • Future Secured!

    Recently we have had reason to celebrate and think to the future, as RSPB Cymru and Severn Trent Water have come to an agreement which sees the RSPB take on a long term Farm Business Tenancy lease of Tŷ-Llwyd farm. Full story can be read HERE.

    View from Yellow Trail looking over Dam towards Ty Llwyd Farm (Photo by Gavin Chambers)

    The agreement will give us more control of how the farm is run which, while working with Natural Resources Wales (NRW), will help develop a more sustainable grazing program across the reserve. With the number of important wildlife species and habitats found at Lake Vyrnwy the grazing is vitally important as over or under-grazing can dramatically change the flora and fauna which could lead to the loss of certain species.

    The Lake Vyrnwy Estate is important for species such as Hen Harrier, Merlin, Curlew and also Black Grouse which is the most southerly population in Wales. Other important species found are Cloudberry (Rubus chamaemorus), Lesser Twayblade (Listera cordata), Ashworth’s Rustic (Xestia ashworthii), Welsh Clearwing (Synanthedon scoliaeformis) and one of Britain’s rarest ground beetles - Trechus rivularis.

    Cloudberry (Photo by Gavin Chambers)

    Areas of woodland are also part of the agreement which will allow more management to help species such as Willow Tit. To improve the woodlands for our native woodland birds like Pied Flycatcher and Wood Warbler, the removal of non-natives such as conifers and rhododendron would be a very good start.

    Plant of the Week

    Common Rhododendron / Rhododendronau gwyllt (Rhododendron ponticum) (Photo by Gethin Elias)

    The Evil beauty

    The plant is responsible for the destruction of many native habitats and the abandonment of land throughout the British Isles. The reason for this is simple. Where conditions are suitable, Rhododendron will out compete most native plants. It will grow to many times the height of a person, allowing very little light to penetrate through its thick leaf canopy. This effectively eliminates other competing native plant species which are unable to grow due to insufficient light. This in turn leads to the consequent loss of the associated native animals.

    Rhododendron seeds are tiny and hence wind dispersed.  Each flower head can produce between three and seven thousand seeds, so that a large bush can produce several million seeds per year. Although not all the seeds will grow successfully, but given the right conditions, a good many will germinate.

    Introduction to Britain: Rhododendron ponticum is native to countries in the western and eastern Mediterranean such as Spain, Portugal and Turkey and also occurs eastwards through Asia into China. It is not native to Britain, but was first introduced in the late 18th Century. It became especially popular on country estates in Victorian times, providing ornamental value, as well as cover for game birds.

    Previous Blog: All Nature