Walking in the hills above Nant Conwy at the weekend, the woods and hedgerows were alive with the soft ‘tseep’ call of hundreds of Redwings, fresh in from the east. Most were invisible to me, hidden by the leaves while feasting on berries. The arrival of the first frosts in northern Norway last week triggered a huge southwestern movement of migrants from Scandinavia, including thrushes and finches. ‘Vismig’, a portmanteau of ‘visible migration’, has become a popular activity for birders in autumn, with the keenest contributing their counts to a global database called Trektellen. Its website has reported large numbers of migrants in recent days, including more than 200,000 Chaffinches and 100,000 Redwings over a coastal site at The Hague in The Netherlands on Saturday.

Counts in Britain were far smaller, and it takes a few days for birds to filter through to North Wales, but on Sunday and Monday large numbers of Chaffinches were reported over north Anglesey and the Conwy coast. There were counts of more than 2000 Chaffinches at the end of Pen Llŷn, 300 Siskins over Bardsey, and smaller numbers of Bramblings. A couple of Twite flew over Mynydd Mawr and a Lapland Bunting and Tree Sparrow were on Bardsey. The first Fieldfares were reported too, at Cemaes and Hiraethog, and Black Redstarts were on the Great Orme, Bardsey, at Aberdaron and below Holyhead Mountain. Starlings have started to gather at evening roosts on Anglesey, at Rhosneigr, Parys Mountain and RSPB Cors Ddyga.

The last few stragglers of summer include a Swallow at Uwchmynydd, and Wheatear and Arctic Tern at Cemlyn on Monday. There was a Common Tern at Traeth Lligwy and Ring Ouzels on the Great Orme and by Llyn Trawsfynydd on Sunday, and last week a Woodlark was seen at Aberdaron.

A new report shows that one-third of Europe’s bird species are declining and 20% are threatened or near-threatened with extinction. The European Red List of Birds, published last week by BirdLife International, uses pan-continental data to assess how close each species is to extinction in Europe. It rates seabirds, wildfowl, waders and raptors as the most threatened, and that the majority of larks, buntings and shrikes are declining.

The speed of some declines are shocking, and include birds that are or used to be regular in North Wales. Among the species that have moved from the Least Concern category to threatened status since 2016 are Merlin, Snipe, Redshank and Rook, while Swift is now considered to be Near-Threatened. All have declined in breeding abundance in Wales in the last 30 years. Several birds that winter here from elsewhere in Europe have also moved into the highest risk categories, including Pintail, for which the Dee estuary is the most important site in the UK.

On a more positive note, some birds have moved in the other direction, to categories of lower concern including species that have been the focus of intensive recovery efforts, such as Red Kite and White-headed Duck. Others, such as Black-tailed Godwit, are benefiting from climate change, at least for now.

Our birds’ connection with the rest of Europe is illustrated by a big influx of Redwings and small groups of Whooper Swans this week, along with winter arrivals that include Lapland Buntings and Firecrest on the Great Orme, Black Redstart at South Stack and a Scaup at Rhyl’s Brickfields Pond. The long-staying Garganey at RSPB Conwy has been joined by a showy Jack Snipe and a Spoonbill is on the Inland Sea. Yellow-browed Warblers have been very scarce this autumn, though one was reported on the Great Orme on Saturday.

Although fewer Jays have been reported on the coast this week, larger flocks inland reported by readers include up to 25 over the Ogwen Valley and 11 over Ewloe. Read this previous blog to find out why.

I’ve spent a week in Northumberland, exploring the coast for winter migrants arriving from Scandinavia. One of the sadder sights, however, has been Guillemots and Razorbills washed up on the beaches, dead or dying. It’s a sight that has been reported down the east coast since late summer, from Orkney to Norfolk, and now auks have been washed up in Norway and the Netherlands. Others have been seen unusually close inshore and even several miles up rivers, but there have been no reports from around the Welsh or Irish coasts, indicating that the problem is in the North Sea.

Many of the auks are emaciated, less than half their typical weight, yet reports from anglers suggest that there is no shortage of small fish. The incidents appear unrelated to stormy weather, which can make it difficult for seabirds to feed and tests by Scotland’s Rural College proved negative for Avian Influenza. One theory is that naturally-occurring algae in the North Sea may be responsible. The bloom was evident on satellite images in September, but it is not yet known whether toxic algae, which can be taken up by fish and shellfish and in turn seabirds, were present. Marine scientists predict that the occurrence of algal blooms will increase in a warming climate, which piles further pressure on species of seabirds that are already in decline.

Back in Wales, the northwest saw the best of autumn migration, with a Red-eyed Vireo at Porth Meudwy, near Aberdaron, just a week after the eighth Welsh record occurred on Bardsey. The island’s Bird Observatory registered a smart Red-breasted Flycatcher, Richard’s Pipit and the only two Yellow-browed Warblers of the autumn. On Anglesey, a Long-tailed Duck and Black-throated Diver are off Benllech and a Cattle Egret at Llanynghenedl, north of Valley. Farther east, a Lapland Bunting is on the Great Orme and a Surf Scoter off Pensarn. The Jay influx continues, with flocks seen on coastal headlands, including an impressive 72 at South Stack on Sunday. If you see four or more Jays together, please do email me with the details.

Several days of strong southwesterly gales and rain made bird-finding a challenge this week, but blew in a top-class North American songbird to Bardsey Bird & Field Observatory on Saturday, where it was caught and ringed. The Red-eyed Vireo, frequently shortened to ‘The REV’ by birders, is only the eight Welsh record and the third for the island, although the first one to have been found there alive since 1985. Widespread in woodland across the United States and southern Canada in the breeding season, the vireo would have been migrating to South America when it became caught in high-level winds that thrust it across the Atlantic. Remarkably, it was recaught at the Observatory on Monday afternoon, having gained two grammes, perhaps around 15% of its body weight. It is only the second North American songbird to be found in Britain this autumn, and gives hope to anyone scouring the headlands of Anglesey or Llŷn.

The southwesterlies also pushed seabirds inshore, including Sabine’s Gulls and several Long-tailed Skuas off Bardsey and Point Lynas, Leach’s Petrel off Cemlyn and a Long-tailed Skua and Grey Phalarope off Aberdaron. The weather system may also have been responsible for a Ring-necked Duck found on Llyn Alaw.

Elsewhere, a Surf Scoter is with a Velvet and Common Scoters off Pensarn, and Garganey and Spotted Redshank remain at RSPB Conwy. Earlier in the week another American visitor, a Bonaparte’s Gull, dropped onto the beach between Rhyl and Prestatyn but stayed only a couple of hours.

Following last week’s mention of Jays on the move, even greater numbers were reported over the weekend: flocks of 22 and 15 over Anglesey’s Inland Sea, 20 over Uwchmynydd and several smaller groups. Even larger numbers have been reported from South Wales, including 161 over Kenfig nature reserve in 90 minutes on Monday morning.