From Russia with love
October is arguably the most exciting month in the rarity-finder’s birding calendar, with the possibility of a new species for the British or Irish lists at its highest. James Eaton takes a look at some of the mouth-watering birds from eastern Siberia that might make it to these shores for the first time this autumn.
It’s October. The weather forecast shows a huge, established high pressure system stretching from the hinterlands of Siberia and across Scandinavia, with an easterly airflow extending over the North Sea. Birders hurriedly take to social media to dissect and discuss, debating where, when and what might fall. Where will the first Yellow-browed Warblers appear? Will there be a sprinkling of drenched, tired Goldcrests littering the first lines of coastal vegetation? Or will a Baikal Bush Warbler turn up in the nets? A what? Every autumn birders hotly debate what new species might be added to the British and Irish lists. They recall visits to the Far East in an attempt to hedge bets on what is possible.
But what is possible? Unlike Nearctic vagrants undertaking the monumental task of flying some 3,000 km across the Atlantic, where one can look to the Azores and Iceland for what has the potential to arrive to our shores, Britain is some way ahead of other European countries with Siberian vagrants, with just a very small number of species having only occurred elsewhere on the Continent. Here we take a look at what species that breed in eastern Siberia and winter to the south should be on our radar.
On the list
The British list stands at 627 species, with the Irish one at 485. However, despite all the predications and hopes, it’s actually exceedingly rare for a new species for either list to hail from the east. Despite the former increasing by some 70 species since the turn of the century (many due to taxonomic alterations), only 10 of these have been from north-east or east Asia. The last true Eastern Palearctic finds were five years ago, when a Pale-legged Leaf Warbler was discovered, dead, on St Agnes on 21 October 2016, and just days before, the start of the remarkable influx of Siberian Accentors.
Though there have been welldocumented, widespread declines of long-distance migrants throughout the Palearctic there has also been a noticeable shift in species composition. From just 20 years ago when a Yellowbrowed Warbler would mark a good day out, or a Dusky Warbler a well-twitched bird, we can now expect double-figure days of the former and seldom more
than a curious glance at a message about the latter.
One explanation for this has only recently come to light. Habitat alteration, largely down to climatic change, appears to be shifting boreal habitat latitudinally. This in turn is moving the breeding areas of species like Dusky Warbler, Dusky Thrush and Siberian Rubythroat northwards, into locations that had been previously occupied by species such as Lapland Bunting, in the space of just 20 years (Ktitorov et al 2021), meaning they are breeding closer to us, while also having to migrate further – hence the recent surge of all three species.
A look at the distribution of some of the most sought-after, oft-annual species – such as Lanceolated and Pallas’s Grasshopper Warblers, Pechora Pipit and White’s Thrush – points to birds with vast breeding ranges, covering almost the entire length of Russia and reaching fewer than 3,000 km from Britain’s coastline, but with much more concentrated wintering ranges, to the south and east. There is not one passerine with such an extensive Palearctic breeding range that has yet to be found; however, there is one non-passerine with a far more extensive breeding and wintering range: Pin-tailed Snipe.
It surely can only be down to identification difficulties and the furtive nature of snipe for this not yet to have been found. So, don those wellies and skirt round marshy edges in the hope of hearing that tell-tale, squeaky kwerrk. Dark underwing coverts, lack of a white trailing edge and the short bill would be the notable features in flight. Then, once on the deck, short bill, barely any tail projection, narrow loral stripe and the classic buffish-barred wing coverts. A photograph of the spread tail would be required to discount Swinhoe’s Snipe – another possibility after the displaying Finnish bird in summer 2008.
Marsh potential
Though we tend to discuss potential passerines reaching our shores from Siberia, there are a number of marshland birds that have potential. One of which, Von Schrenck’s Bittern, has already made it to Europe – albeit at a time when it would have been considerably more numerous – when one was shot in north-west Italy in November 1912 (Haas and Crochet 2012). This species hugs the Amur River floodplain some 6,000 km away from Britain, and winters way to the south in the Sundaic region. Another with a mirroring range is the locally numerous Band-bellied Crake, a highly elusive Rallid but occasionally prone to being found in ornamental parks, à la the Sunderland Baillon’s Crake.
As autumn draws to a close, or clear skies mean little to search for in the coastal thickets, have a scan through the flocks of Eurasian Curlew – perhaps a Far Eastern Curlew is waiting to be found. Though their impressively long bills stand out, keep an eye out for the thickly barred underwing coverts and all-dark rump. European Golden Plover flocks should be searched for a longoverdue Oriental Plover, a species that’s already occurred in four European countries.
Two long-distance migrants with massive breeding areas that have occurred in Europe are Oriental Cuckoo and Dark-sided Flycatcher.
An autumn cuckoo will require an in-hand analysis, but how a Dark-sided Flycatcher has managed to evade detection here is quite something, especially given its previous occurrence in Iceland (October 2008). This abundant species, which loves to sit out on open perches sallying for insects, has a similar migratory path to Asian Brown Flycatcher. Speaking of flycatchers, isn’t it about time we put to bed ghosts of the past and enjoyed another Mugimaki Flycatcher?
In recent years, the exciting discovery that both Pale-legged Leaf and Eastern Crowned Warblers have the ability to reach Britain opens up a whole host of new, exciting possibilities. Both Phylloscopus breed 6,000 km away, east of Lake Baikal and the Lena River, the most easterly of the great Siberian rivers that flow to the Arctic. Pale-legged Leaf Warbler winters throughout much of mainland South-East Asia, while Eastern Crowned winters primarily from central Thailand to Indonesia.
There’s a long list of species that occupy a very similar breeding and wintering range. Mirroring Pale-legged are Oriental Scops Owl, Chestnutflanked White-eye and Black-naped Oriole, along with a favourite of mine, White-throated Rock Thrush, which actually stretches west to Lake Baikal, theoretically making it even more likely. Meanwhile, Ashy Minivet, Grey Nightjar, Daurian Starling and Tiger Shrike are similar in their distribution to Eastern Crowned Warbler.
A species seemingly far more likely than either of those two Phylloscopus is Baikal Bush Warbler. It breeds some 1,400 km further west of Lake Baikal, to Novosibirsk along the River Ob (around 4,600 km from Fair Isle), and is a common winterer in marshland from Thailand to north-east India. I often record it on the same wintering patches as Siberian Rubythroat, Pallas’s Grasshopper and Lanceolated Warblers. It readily calls, too, giving away its presence rather easier than other skulkers. One for the Northern Isles nets or scuttling away down a burn – pay particular attention to the broad, whitefringed undertail coverts (similar to the larger River Warbler) if you are lucky enough to find a Locustella creeping through the tussocks, but also be aware that the larger Chinese Bush Warbler could also be a possibility, despite its slightly more contracted range.
In numbers
Keeping with marshland warblers, two of the most abundant Far Eastern Palearctic passerines are still to be recorded anywhere in Europe: Blackbrowed Reed and Oriental Reed Warblers. The latter has reached Israel and Australia, so we know the potential is there, and both are strong September-October migrants. We shouldn’t forget the arch skulker of them all: Gray’s Grasshopper Warbler, which has been recorded in both France and Denmark in late September. It has the classic breeding range from Ussuriland west to the River Ob, but is a migrant to eastern Indonesia, which could mean a journey of some 7,000 km. It more than has the ability to make the distance, but this might be the problem, as it appears to be such a strong flyer that it’s one of the very few Eastern Palearctic migrants to remain unrecorded from Hong Kong. Timing of migration undoubtedly
plays a part in what we can expect, as two abundant, widespread species – Forest Wagtail and Yellow-rumped Flycatcher – are early migrants. At the time of writing, in mid-August, the first few are already passing through Bangkok, with most on their wintering grounds by mid-September. However, this hasn’t prevented other early migrants from making it to British shores: Eastern Crowned Warbler follows a similar pattern, yet all four records have been in October, going to show that we can still expect the unexpected, and perhaps some vagrant passerines are using a more leisurely route to British shores.
As our knowledge of cryptic species has increased markedly in recent years, certain birds are appearing with increased frequency – a particular case in point being Stejneger’s Stonechat now being an annual visitor having only been found for the first time in Britain in 2012 (at Portland Bill, Dorset).
Perhaps the next species to follow suit will be Siberian House Martin, split from [Common] House Martin earlier this year based on an in-depth analysis by Leader et al (2021) of sympatric breeding and field characters. With a breeding range covering much of the eastern half of Russia and Mongolia, surely it’s more a case of them being overlooked than not making it here.
This common long-distance migrant means that any house martin from October onwards should be scrutinised. Though adults stand out with their snow-white (not black) uppertail coverts, immatures are rather more subtle, with dark-centred, white uppertail coverts, along with a slightly shallower tail fork and shorter tail, rendering an identification by a back-of-camera screengrab on social media most likely.
Take a look
It is often the case that it is only when cryptic taxa are recognised as a species that we look at how to identify them. One of these is Mongolian Short-toed Lark, a split from Greater Short-toed Lark just this year that shares breeding and wintering ranges with Richard’s and Blyth’s Pipits.
Any ‘short-toed lark’ found in
October should be checked for the much warmer, richer flanks and breast, buff-tinged (not white) belly, with a more uniform crown to upperparts, lacking the rufous-tinged crown of most Greater, and longer wings. The call is also significant: a fast, bouncing series in flight, heu-du-du-du, or single trup when perched – quite different from the short, dry trrep of Greater (Alström and Sundev 2021). Perhaps a trawl through past photos of autumn short-toed larks on a cold, wet day will be the easiest way to discover this species.
There are an additional number of species that have been oft-touted, but a lack of others with similar ranges appearing in Europe makes them arguably beyond the realm of possibility. However, never say never, as this July proved, when a well-tuned birder discovered a singing Kamchatka Leaf Warbler in Finland – a species breeding in the ‘Ring of Fire’ of the Far East and wintering east of mainland Asia, primarily in the Philippines and Indonesia. Perhaps we can even start dreaming of Grey-streaked and Blueand-white Flycatchers, too!
History has shown us that despite all the hype and discussion, the chances of new Siberian gems turning up are exceedingly slim, but it’s what keeps us going and adds to the lure and mystique of migration. This potential for such a star-studded cast is why we continue flogging islands and headlands in wet, grey, blustery conditions each and every autumn! ■