With summer now appearing to be fading in to the past, Autumn has really taken over with autumnal colours now splashed across the countryside and the weather turning far more ‘autumnal’. Storm Callum is about to be the third storm to hit the UK giving the impression we might be in for a stormy season. This is the season of change and that is very true for wildlife.

Bird migration is in full swing with birds heading south for the winter to supposedly find nicer weather, though it’s all relative. There is usually a quiet spell where summer birds have left but the winter birds haven’t arrived yet and so there appears to be a lack of activity. This is especially true for Lake Vyrnwy as we are not on a typical migration route for most species. We did receive a report from a fisherman on the lake who had seen a small white bird, size of a small pigeon feeding on insects off the water which we can only think was a grey phalarope. This coastal bird is likely to have been blown in during one of the recent storms, but sadly was not seen again after the initial sighting.

A lot of our winter birds come from Scandinavia and therefore arrive on the east coast before filtering across the country which means, certainly for the smaller passerines, it takes a little longer to move over to Wales. However, larger species like redwing and fieldfare can move quicker though with only small numbers reaching the west early on. The first redwing arrived here on 8th October with a couple calling from the wood behind the office. As can be seen in the graph below from the BTO they appear to have arrived on time compared to their average timings.

Redwing reporting rates (BTO)

However, a smaller passerine, the yellow-browed warbler, seems to be late arriving by 1-2 weeks which is probably due to the weather and general westerly flow of wind/storms which has stopped them attempting to cross the North Sea. Unfortunately, we don’t get too many of them in Wales, with our first reserve records coming in 2016 but they are a species on most birders autumn wish list.

Yellow-browed warbler reporting rates (BTO)

On the flip side to this, species leaving the country like swallow have been doing so a little earlier than average. Again, the weather is likely to be the biggest factor with storms and colder weather being a trigger to encourage birds to depart sooner.

Swallow reporting rates (BTO)

Insects continue to be present with a brief increase in temperatures causing butterflies to re-emerge and swarms of flies to form, with thousands seen over the dam in the last couple of weeks. While walking up the steps up to the dam from the sculpture park a snazzy caterpillar was found crawling across the path. This one will turn in to the Pale Tussock moth next May/June having fed on a range of deciduous trees or shrubs.

Pale Tussock caterpillar

We will have to wait and see what the rest of the autumn brings!

Gavin Chambers, Warden

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