Avon Wildlife Trust BioBlitz at Chew Valley Lake

View from Bernard King hide, Chew Valley Lake

I spent last Saturday volunteering at another ‘BioBlitz’ event, this time on behalf of the Avon Wildlife Trust. Run in partnership with Bristol Water, the event was held at Chew Valley Lake, a beautiful site just to the south of Bristol. This lake not only supplies Bristol with water, but is also great for wildlife and visitors. The site was chosen because it has a wide range of habitats in a relatively small area, so there were lots of different species to record.

Getting up early on a Saturday morning is never easy, but it was worth it to be down at the lake in the early morning sunshine! The weather was beautiful and the lake was mirror calm – great conditions for wildlife spotting.

Low water levels looking out from Bernard King hide, Chew Valley Lake

For this event, I was focusing on the birds – this mainly involved spending time in a hide, being on hand to help point out bird species to the public. There were plenty of baby birds around – the hide seemed to be constantly surrounded by calling baby robins, and there were also young blue tits, song thrushes and a lovely reed bunting family nearby. Out on
the lake itself there were the usual cormorants, swans and gulls, including at least half a dozen greater black-backed gulls just in front of the hide. The photo below gives some idea of how much bigger these impressive gulls are in comparison to the lesser black-backed gull, which is one of the more familiar species in cities such as Bristol.

Greater and lesser black-backed gulls
Greater black-backed gull (left) and lesser black-backed gull (right) - note the size difference.and the different leg colours.

Out on Denny Island, in the middle of the lake, there were a couple of little egrets feeding, together with several herons, a common sandpiper, and lots of coots and ducks. We also got good views of a roe deer running along the shore! The reeds around the lake edge were full of singing reed buntings and dozens of reed warblers – their scratchy songs ended up stuck in my head for hours after I’d gone home! There was also wildlife of the smaller variety inside and around the hide itself, including various different spider species, harvestmen, banded snails and a somewhat dozy ladybird, while a mystery gnawing sound turned out not to be a rodent but instead a wasp busy chewing at the outside of the hide!

Harvestman - a type of arachnid related to spiders.
White-lipped banded snail
White-lipped banded snail, Cepaea hortensis

In the afternoon, I was able to tag along on a mammal walk where we spotted the tracks of a hedgehog, stoat, roe deer and even an otter – really good to know they’re about and I’ll be sure to look out for their tracks down there in future!

Otter prints, Chew Valley Lake
Otter prints

There are also some lovely wildflower meadows around the lake, so lots of invertebrate life, including grasshoppers, ladybirds, butterflies (including ringlets and marbled whites), damselflies, caterpillars and spiders. And of course all the wildflowers themselves. All the plants, trees and fungi were also being counted, although it was sad to see the horse chestnut trees in the woods once again infested with leaf miners (Cameraria ohridella), a moth whose larvae feed on the leaves and can do a lot of damage. Still – another species
for the list!

Peacock butterfly caterpillars on nettles
Peacock butterfly (Inachis io) caterpillars on nettles.
Seven-spot ladybird
Seven-spot ladybird (Coccinella 7-punctata)


Wildflowers, Chew Valley Lake

As with other BioBlitz events, the aim of the day was both to engage the public and to see how many different species could be found at the site. So far, the total is over 500 species and counting – keep an eye on the Avon Wildlife Trust website for updates.

You can also find out more about BioBlitz events at the Bristol Natural History

If you want to know more about the birds and other wildlife at Chew Valley Lake, take a look at the CVL Birding website for more information.

2 thoughts on “Avon Wildlife Trust BioBlitz at Chew Valley Lake

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