Great expectations

Dan Brown

In light of the recent spate of extralimital seabird records in the North-East Atlantic, delves into their origin and the causes of vagrancy, as well as speculating on potential future arrivals.

Over the past few decades the expectations of many seawatchers have risen. Formerly, Wilson’s Storm Petrel and Fea’s Petrel would have made a birder’s year. A fly-by Black-browed Albatross would have been the pinnacle of seawatching experiences, but 2020 has set the bar substantially higher. Why? And can we expect this trend to continue?

Seawatching is often viewed with suspicion. Why subject yourself to miserable conditions and frequently poor and brief views of a bird when you can simply get on a boat and enjoy much closer views? Well, unlike the eastern and western seaboard of the

United States or the coasts of New Zealand or South Africa, Britain is not blessed with monumental marine canyons. In fact, we have a pretty massive expanse of shallow continental shelf out to our west and the North Sea is more of a paddling pool.

It is the drop-off of this shallow continental shelf into deep abyssal water that is generally – but not always – the richest area for seabirds. Here cold water upwellings deliver nutrients to the surface which kickstarts the propagation of life, plankton and zooplankton, which in turn sees an abundance of predators taking advantage. Seabirds are no exception. Anyone desperate for some deeper water could head out to the very western fringes of our territorial claim to the sea areas Sole and Fitzroy off south-west Britain or Bailey and Rockall off western Scotland. This is likely to make even the most seasoned seagoer go green, requires an overnight (probably multiple) expedition and has no guarantee of success.

However, inshore boat trips off the UK have also demonstrated success, with Scilly Pelagics illustrating that effort pays off, with this summer’s Zino’s Petrel, tens of Wilson’s Storm Petrels

as well as Fea’s-type Petrel in previous years. Most of us, though, will have to make do with a headland.

Expand your search image

For the seawatcher and pelagic go-er alike, our search image has been primed to detect larger shearwaters (Cory’s and Great), suss out Wilson’s from the more numerous European Storm Petrels and lock onto the kamikaze arcs of Pterodromas. But there’s plenty more out there to look for.

When it comes to seabirds (and I use that term from here to include all seabirds rather than just tubenoses), our minds should be open to almost anything. The last couple of decades have seen species from the North

Pacific, Southern Hemisphere and tropics and there’s no reason why more shouldn’t follow suit. In fact it’s highly likely that they will.

We journey to headlands armed with much better optics than 30 years ago. Field guides and identification material have progressed enormously and many more people have had the opportunity to experience some of these sublime species ‘in the field’ while onboard expedition cruises and undertaking ferry journeys, not to mention foreign pelagic trips. Every year we learn a little more about seabird movements, while our ability to predict weather has also advanced.

Global climate change and intensification of weather systems is also likely to be a driving force in bringing remarkable seabirds to our shores. Fastmoving and intense weather systems force birds inshore – known as ‘wrecks’ – and potentially into fields and onto reservoirs near you.

This isn’t a new phenomenon: the last Magnificent Frigatebird graced a pasture in Shropshire, Derbyshire’s Black-browed Albatross was halted in its tracks by electricity wires and Norfolk’s Black-capped Petrel ended up in a gorse bush.

Across the pond, land-locked Arizona witnessed an incredible deluge of seabirds deposited by Tropical Storm Nora in 1997, this included 100-200 Black Storm Petrels on Lake Havasu, while Montana has recorded Manx Shearwater! As weather systems become more intense we can expect more seabirds inland.

Which way to look?

Our planet is beautifully connected by oceans and for seabirds it’s all fair game. The main limiting factors tend to be a species’ dispersal ability, the presence and force of wind, and foraging potential. Some species are tropical or subpolar specialists, but many will traverse the equator between seasons and with an unhindered ability to move they can and do turn up just about anywhere. Both Swinhoe’s Storm Petrel and Manx Shearwater have demonstrated the ability to seemingly colonise new oceans (the Atlantic and Pacific respectively) so anything is possible! The North Pacific is the world alcid hot-spot and the UK and Western Palearctic (WP) has already been graced by several of these crippling species, most famously Devon’s Long-billed and Ancient Murrelets. Tufted Puffin has also put in multiple appearances in the WP and there are records of Parakeet and Crested Auklets. Quite how these alcids are making their way to us remains unknown, although species such as Long-billed and Ancient Murrelets are well known for their vagrancy abilities, with records along the eastern seaboard of the States as far south as Florida.

The North-West Passage is one of the most infamous Arctic navigation routes, having only been successfully crossed for the first time without an icebreaker in 2007. It commences in Baffin Bay and snakes between Banks and Victoria Islands (Arctic Canada) before heading west through the Beaufort Sea and south into the Bering Strait.

Its notoriety is due to the continual presence of sea ice that locks up the passage and prevents navigation. In recent years, though, climate change has seen this sea ice substantially retreat, ship navigation increase and anecdotal evidence suggesting that some species of birds and mammals are either taking advantage of new feeding grounds or following the ice edge east.

In 2019, Short-tailed Shearwaters were observed feeding in the pack ice around Banks Island and huge flocks were also encountered slightly further west. In the same year no fewer than seven species of alcid were recorded flying rapidly east past Herschel Island, with observations of Crested Auklets moving further east over the pack ice. Kittlitz’s Murrelets were also found just west of the Canadian border

and a Grey Whale observed in the Mediterranean is thought to have arrived in the Atlantic via this route. As much as a Red-legged Kittiwake on Bempton Cliffs would be beyond mega, it is probably unlikely to make it over due to relatively local dispersal in the North Pacific. On the other hand, Pacific Fulmar or a second Aleutian Tern are far more likely to make it to our shores due to dispersal and, in the case of the former, abundance.

The North-East Passage

– running along the northern coast of Siberia – has also become more accessible in recent years and the arrival of a Tufted Puffin on Bear Island, Norway, would hint at an arrival from the east. We have seen occurrences of rare alcids in December (all three Long-billed Murrelets), spring (Ancient Murrelet and Tufted Puffin) and September (Tufted Puffin). It would certainly pay to scan all alcids at all times of year.

Breeding Pacific alcids occupy a variety of coastal habitats, for instance Parakeet Auklets tend to breed low down in boulder fields, Crested Auklets anywhere on vegetated boulder fields and Horned Puffins on cliff-faces. Crested Auklet is abundant in the

Arctic Ocean and must rank as a strong contender for finding its way onto the British list; even Least Auklet could potentially find its way over here.

Hot water

Over the past couple of decades, and especially the last few years, there has been an apparent upward trend in tropical and subtropical seabirds arriving on our shores. Masked, Redfooted and Brown Boobies have all occurred in north-west Europe, with the latter notching up five-six British records in the past two years. Red-billed Tropicbird and Sooty Tern have also apparently increased in regularity – all six records of the former are from this century.

It is certainly not unreasonable to expect more if sea water temperatures continue to warm. We should also be on the look out for congeners – Whitetailed

Tropicbirds have bred on Cape Verde this year – so maybe it’s time to revisit the 2013 Cumbrian bird – and it’s certainly worth checking Northern Gannets for a Cape.

There are also a number of subtropical Procellariiformes which have flirted with the British list, namely White-faced and Band-rumped Storm Petrels and Bulwer’s Petrel. Both should be on the radar of seawatchers and especially those on pelagic trips. White-faced Storm Petrel in particular is notoriously land-shy and very difficult to pick up at sea due to its coloration. When the next live one

graces the British Isles – and one will

– it will almost certainly be seen from a boat. Cape Verde Shearwater has been recorded off North America and could easily make it to the South-West Approaches. Among the terns Brown Noddy is a distinct possibility, but Black Noddy might be more likely.

The subtropical and tropical waters of the western Atlantic also offer a few tantalising possibilities, not least Blackcapped and even Bermuda Petrels. The latter has made it into Irish waters and the former has two British records. Interestingly the records of both species fall between December and May, with a number of other spring records from the eastern Atlantic indicating that some well-timed spring seawatches and pelagics may pay dividends.

Any claim of Audubon’s Shearwater is likely to raise eyebrows due to the intricacies of at-sea identification, but it should be well and truly on the radar of seabirders and wardens of Manx Shearwater colonies.

From the far south and beyond

The South Atlantic holds a list of mouth-watering species, many of which are dream birds and some with a distinct possibility of cruising past a headland near you. This year has already seen several crippling Procellariiformes in the WP and there’s a good chance of repeat performances from species such as White-chinned Petrel and Atlantic Yellow-nosed Albatross.

If setting those as your search image wasn’t enough, though, bear in mind the likes of Light-mantled or one of the ‘Great’ albatrosses. Imagine a Snowy Albatross cruising past Pendeen – it’s not an impossibility! Tristan/Wandering Albatross has been recorded from Norway, Italy and Portugal, while Lightmantled has been noted in the North Pacific.

The main hurdle larger albatrosses face in getting north is crossing the equator. This tropical belt is notorious for its lack of wind – the doldrums – which often inhibits or at least hinders passage north. If any one individual makes it across the equator, there is a very real possibility of it circulating past the UK. White-capped Albatross and potentially Salvin’s and Shy Albatrosses are also not out of the realms of possibility. Neither are the giant petrels, although identifying any of these at sea is far from straightforward. Many of the larger seabirds are not land-shy, making them a possibility from headlands; however, some smaller species are maybe more likely to be drawn in by chum. Cape Petrel and Antarctic or Slender-billed Prions could fall into this category, as could the Fregatta storm petrels. Black-bellied has now been found several times off the Canaries and with two unidentified Fregatta records in the UK it’s only a matter of time before one is confirmed to species level.

Of the larger shearwaters, Fleshfooted and Short-tailed are the most likely British vagrants, but Wedgetailed could also spill out of the Indian Ocean and north. Buller’s Shearwater could feasibly do the same from the Pacific and is at least a straightforward identification.

Perhaps some of the most exciting potential prizes, though, are the Pterodromas and Procellarias. Atlantic and Soft-plumaged Petrels are both very real possibilities, and species such as

Kerguelen Petrel are not completely out of the question. Two species that particularly get the pulse racing are Mottled and Spectacled Petrels. The latter is scarce but occurs in the South Atlantic and has vagrancy potential. The former is abundant in the Pacific and makes monumental migrations from Antarctica to the Bering Sea. Both species are not at all land-shy and are easy to ID at sea – this is perhaps my ultimate extreme seabird punt for the UK! ■

❝When it comes to seabirds, our minds should be open to anything”❞ almost

Until last summer few would have considered Brown Booby as a potential British first, but then came an outstanding run of four birds along the south coast.

The single British record of Aleutian Tern dates back to 1979, but this long-distant migrant could be overdue a repeat appearance.

Yorkshire’s Black-browed Albatross (this photo) makes for an arresting sight among the Northern Gannet colony. It has been very popular with birders the summer. But could something even more unexpected such as Salvin’s Albatross (below) join it in British waters?

A Short-tailed Shearwater in France (above) and a Flesh-footed Shearwater (below) this August raise hopes of either species being seen in Britain.