Lake Vyrnwy

Lake Vyrnwy

Lake Vyrnwy
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Lake Vyrnwy

  • 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

  • All Nature



    Despite the poor season for nest box breeding birds the woods are still alive with the sound of newly fledged birds. Tit families, high pitch squeaking Goldcrest chicks and Warblers have been quite noticeable. A few warbler nests that have been monitored appear to suggest that food has not been as much of a problem for them, however given they are ground nesters they are very vulnerable to being predated which unsurprisingly a small proportion have been.

    We have our fingers crossed for a pair of Great Crested Grebes nesting on the lake. In recent years they have failed to successfully raise a family mainly due to the fluctuating water level, which given the recent very high level will hopefully stay high enough for long enough. Around the lake the loud piping call of Common Sandpipers has given away the likely presence of youngsters hiding away in the lakeside woodlands with one found in the last week.


    Young Common Sandpiper around Lake Vyrnwy (Photo by Gavin Chambers)


    Warmer weather has given the Butterfly transect a bit more life, with 8 species recorded on the 16th June. This included the first Small Pearl-bordered Fritillaries and Large Skippers of the year. A few Painted Lady butterflies have been seen this week, which if reports are to be believed will be arriving in the UK from Africa/Southern Europe in their millions this summer (A Painted Lady Summer)


    Painted Lady (Archive Photo by Gavin Chambers)

    Butterflies seen so far this year: Painted Lady, Meadow Brown, Small Pearl-bordered Fritillary, Large Skipper, Small Copper, Small Heath, Green Hairstreak, Peacock, Red Admiral, Small Tortoiseshell, Orange-tip and Green-veined White.

    Dragonflies and Damselflies

    They are slowly starting to emerge from ditches, pools and boggy areas. Species list so far this summer: Large Red Damselfly, Azure Damselfly, Common Blue Damselfly, Four-spotted Chaser and Golden-ringed Dragonfly.


    Four-spotted Chaser (Archive Photo by Gavin Chambers)


    While monitoring birds on the uplands the emergence of beetles has been noticed, especially Garden Chafers and the Coppery Click Beetle (Ctenicera cuprea) which tries to avoid danger by jumping with a clicking mechanism in its neck. It is one of the largest click beetles in the UK and can leap at speeds of more than 2m/s. Moths have been more prominent with the recent warmer nights, 42 species caught on the 20th June. Eyed Hawk-moth was nice to catch, their large ‘eyes’ used to scare off any unwanted attention. The biggest surprise was finding a new micro species for the reserve and county (Montgomeryshire) in the form of a Six-spot Groundling (Prolita sexpunctella), a moorland species that has probably been overlooked given its preferred habitat is generally remote.

    Eyed Hawk-moth caught at Lake Vyrnwy (Photo by Gavin Chambers)

    Plant of the Week

    Heath milkwort / Amlaethai (Polygala serpyllifolia) (Photo by Gethin Elias)

    Walking through rushes and Deergrass, you may come upon its scatterings of dark purple, blue, light blue and white on the south facing slopes of higher, better-drained ground, with splashes of more intense colour from other plants such as Common Tormentil and Wild Thyme.
    Milkwort replaces, Common Milkwort on acid soils, and you can pretty much assume that any Milkwort growing in heathland or acid grassland is this species. To be sure, however, look at the leaves. The lower leaves of Heath Milkwort are arranged opposite one another towards the base of each stem, whereas those of Common Milkwort are alternative. The flowers on Heath species are usually slightly smaller, too, and of deeper but less bright colour than those of Common form.

    Previous Blog: Ups & Downs

  • Ups & Downs

    In the last blog it was mentioned that Tit species had struggled to raise broods and that Pied Flycatchers were just hatching with a heatwave forecast later in the week. Well we got a mini heatwave but night temperatures were still getting close to freezing during clear nights. Also, before the heatwave, we had an absolute deluge of rain and strong winds generally over the night of the 1st June and into the 2nd. A camera trap set near the Centenary Hide showed the dramatic rise in water levels (take note of time in bottom right corner of video).

    Time-lapse using Camera Trap outside Centenary Hide

    Our volunteer and local ringer, Mike Haigh, has the job of checking all the boxes spread across the reserve along with a small team of helpers. He has provided a summary of the box checks so far this year:

    “Box occupancy very good with 66% boxes used, with 298 nests found of 6 species (Blue, Great & Coal Tit, Pied Flycatcher, Redstart and Nuthatch). Blue Tit and Great Tit nest attempts has increased on previous years following the high breeding success in 2014 and a warm winter and Pied Flycatchers nest attempts are also slightly up by approximately 10%.


    All birds in small nest boxes require caterpillars to feed the young and the cold nights of 2015 have caused a severe shortage of moths and therefore, chick food. Consequently nesting failure is already worse than last year (and we haven’t yet completed final checks).

    33% of Pied Flycatchers have already failed and this total will increase as we discover more dead broods during further box checks (last year approximately 1 in 4 nests failed which is a more typical failure rate). In addition the number of chicks in surviving broods are reduced with siblings either dying through lack of food or eggs not hatching due to poorly conditioned adults.

    2 days of high wind and torrential downpours from 31 May made things even more of a struggle as caterpillars were washed from trees parents found it hard to forage.

    Fledgling Pied Flycatcher from Lake Vyrnwy in 2014 (Photo by Gavin Chambers)

    It's not all bad news though - healthy fledged Pied Flycatcher chicks being fed by adults have been seen this week. Our Pied Flycatchers are ringed as part of a long term scientific study and this always produces interesting information. Pied Flycatcher winter in Sub-Saharan Africa and complete a round trip of 13,000km to return to Lake Vyrnwy, quite often to the same wood in which they previously nested and in one case this year, the very same box. We also have 2 Pied Flycatcher sisters who fledged last year, flew to Africa and returned to nest in adjacent boxes at Lake Vyrnwy!”

    One wet misty morning we spotted a female Goosander sitting on the shores of the lake and she appeared to be sheltering a family, though it wasn’t until a couple of days later that we found her with 6 healthy looking ducklings. Could this be the family from one of our boxes mentioned in a previous blog? Other fledglings have included Pied Wagtail, Long-tailed Tit, Dipper, Willow Warbler and a couple of Mallard ducklings in front of the Centenary Hide. An Otter was seen below the dam on the 11th and was enjoying by several staff members during their lunch break during an RSPB Mid-Wales meeting.

    Fledged Pied Wagtail (Photo by Gavin Chambers)

    Plant of the Week

    Common Butterwort / Tafod y Gors, (Pinguicula vulgaris) (Photo by Gethin Elias).

    This is an insectivorous plant. Each leaf is curled at the edges and, when an insect lands, the sticky surface of the leaf holds it fast. The victims struggle to free itself and activates a curling mechanism on the leaf margin. The leaf then secretes digestive enzymes to break down the still-living body, and absorbs the nutrients through its surface. When it gradually opens again, the undigested bits are blown or washed away. Its flowers vaguely resemble a violet in a kind of old-lady mauve - hence its other common name of Bog Violet.

    Previous Blog: It's all about Food