(English) Butterflies and Lakes
Last week we set out with the intention of monitoring Butterflies, as part of the Big Butterfly Count. However, although the weather was still quite warm and humid, it was dull and not only were there almost no Butterflies around – we saw one White in the Double-Walled Garden – but there very few other insects flying about. A look at the beehives confirmed this lull in activity as the only bees around were mainly milling somewhat listlessly around the entrances to the hive. But eventually, around midday, as we meandered around above the slate beds, the sun came out a few Butterflies started to appear. It was then we realised our other problem, namely that the five of us on that particular walk weren’t really that good at recognising Butterflies. So we gave up and settled for the usual tea and chat.
This week we were pleased to be joined once again by Chris, his partner and three other Swansea Met students, plus Jan, who does know her Butterflies, and Michael. But rather than just concentrating on Butterflies – the actual count is only supposed to take 15 minutes – the intention was to start monitoring the three lakes using a list of questions that Bruce had compiled. In reality, to answer all the questions would take far, far more than a single mornings walk around them, so the idea was to get general impressions as a starting point.
The first thing was to correct an impression that some of us had - that is that the lake nearest the Gatehouse is the lowest and that the others are progressively higher. The truth is the exact opposite and the illusion is caused by the lie of the land – the fact that you travel up the Broadwalk together with the height of the Great Glasshouse. The lakes are fed by the stream by Plant Sales, then flows from Pwll Yr Ardd near the Gatehouse, the shallowest of the lakes, under the bridge by the Aqualab into Llyn Uchaf, thence via a weir and under another bridge into a stream and then into the third lake, Llyn Canol, over another weir and into another stream which had originally fed Llyn Mawr, which no longer exists.
The three lakes each have a distinctive character. The first on the Broadwalk is normally home to Mallards, Coots and Moorhens, but the latter two were noticeable by their absence. This also tends to be a rather shallow, muddy lake and the water looked very brown, possibly because of the recent heavy downpours.
The second lake is, according to tree experts, about 3 foot too high for the long-term health of the mature trees around it. But to lower the level of the lake would mean reducing the wall of the sluice – a big job – and would undoubtedly create problems elsewhere. This lake is full of yellow and white water Lillies, possibly native species and, as we discovered along just one small patch, full of water insects of all kinds.
The third lake is different again and the far reaches of it often harbour all kinds of water fowl, as well as kingfishers. We didn’t see any of the latter but we were very pleased to see a Little Grebe sitting on a nest, floating in the middle of the lake well away from everything else. This lake tends to suffer from algae, presumably from nitrates leached into the stream water that feeds the lakes from surrounding farmland. A local school has come up with a technical idea to reduce this using a spinning wheel device – this has just won a UK Design award and now they are going for a European award.
407 Little grebe and Toad photos.
As we were passing from lake to lake we did try to count the Butterflies. Again, the major problem was in identifying them on the wing as with the warm weather they were very active. An additional problem, as far as the big Butterfly count was concerned, was in establishing an area to do the count as the Garden is simply enormous. In the end it was agreed that the best that we could hope for was to identify them and get a rough idea of numbers, as a reference point for future Garden surveys. So what did we see? Lots of Whites, Small, Large and probably Green Veined and quite a few Meadow Browns and Ringlets, plus the occasional Tortoiseshell and Gatekeeper. We didn’t see any Common Blues though we know they are around from previous walks and I saw a solitary male on the following Saturday.
406 Butterfly photos.
And then there was Toad heaven – namely the wood chippings in the area beyond the bridge by the entrance to Waun Las. Dozens, maybe hundreds of tiny Toads hopping around, presumably enjoying the many insects that this habitat has created.
Finally, something for everyone to consider. Before we went out Bruce had posed a number or questions, some of which are below. If anyone has any comments on these then please send them to either myself or Bruce.
- Should the lakes have more ornamental plants in them? Should we be going for the Monet water lily ponds look? How might this affect wildlife?
- What lives along the small stream/copse that adjoins lake 2 and 3? We saw small mammal holes in the stream bank last year.
- How should we attract more wildlife onto the lakes? Should we have lookout branches for kingfishers? How do we do that?
- The 3rd lake suffers badly from algae – But what is the algae? How is it affecting wildlife?