Birdwatch

Gull potential

Two species found south of the Sahara may seem unlikely additions to the British list, but recent evidence suggests otherwise. Josh Jones takes a closer look.

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Birders are well versed in looking to the east or west for the next big rarity. But what about the south? Admittedly, Afrotropic­al vagrants are generally few and far between in their occurrence, even in the southernmo­st reaches of Europe, let alone Britain – three Allen’s Gallinules, all dead or dying, over a 115-year period more or less covers our share of the spoils.

That said, there are two species which, although initially appearing fanciful as potential vagrants, are arguably among some of the more likely next additions to the British list. These are Kelp and Grey-headed Gulls, both widespread species of the Afrotropic­al region and with ranges just about extending into the Western Palearctic. What’s more, both species have showcased examples of their vagrancy potential over the years – and especially so in the past two decades, with European records on the up. While this might reflect a genuine upturn in occurrence­s due to a northward range expansion, it is equally as likely explained by improved observer coverage and awareness – many more birders look closely at gulls nowadays, and the rise in digital photograph­y has undeniably ensured that mysterious or unusual-looking birds are almost instantly documented, and don’t ‘get away’ like they used to.

Here I take a closer look at each species, accounting for past appearance­s in Europe and discussing their potential to make it to Britain in the near future.

Cape crusader

When an adult Kelp Gull was found at Paris Zoo, France, in January 1995, European birders were unanimousl­y dumbfounde­d – how could it be that a potential first for the region had appeared at such an unexpected location? Unsurprisi­ngly, the possibilit­y of an escaped bird was mooted, but no evidence could be found to confirm that suppositio­n and, despite the seemingly impossible circumstan­ces, it was accepted as a first for France and the Western Palearctic (WP).

Kelp Gull Larus dominicanu­s is a familiar bird in maritime Southern Hemisphere, with five recognised subspecies. Nominate L d dominicanu­s is the most widespread, being found around the coasts of South America (including South Georgia and other subantarct­ic islands) and Australasi­a. Other subspecies are present in the Indian Ocean and Antarctic, but it is vetula of southern Africa which accounts for all accepted Kelp Gull records in the WP – and what this article focuses

on. This taxon, commonly known as Cape Gull (and referred to as such hereafter for clarity), is often considered a candidate for full species status and adults are distinct in that they have dark eyes, unlike the pale yellow-white of the other subspecies.

Since the turn of the century, the WP status of Cape Gull has changed rapidly. Breeding commonly in coastal southern Africa, it has been gradually spreading northwards along the coast of West Africa since the 1980s and, reflecting this, WP sightings began to take a significan­t upturn. Initial records include a long-staying adult at Banc d’Arguin NP, Mauritania, from 19972007 and coastal Morocco in 2006.

Four adults at Khniffiss Lagoon, Morocco, in 2008 marked the beginning of a new chapter in the species’ evolving status in the WP. The Khniffiss situation initially proved confusing, with at least some of the birds seen in 2009 turning out to be Great Black-backed Gulls, breeding alongside (and sometimes in mixed pairs with) local Yellow-legged Gulls. This in itself was an astonishin­g revelation, given Great Black-backed was previously only known to nest as far south as northern Spain.

What’s more, several hybrids (presumed to be Yellow-legged × Great Black-backed Gulls) were present around the colony, some of which looked strikingly similar to Cape Gull. However, despite these pitfalls, pure pairs of Cape Gull were also proven to breed in 2010 and subsequent years, confirming that the species was now reproducin­g in the WP.

As a result, awareness of the species has increased exponentia­lly and, with growing numbers of birders visiting southern Morocco and Western Sahara, Cape Gull records have become a regular feature from the coast as far north as Agadir. Generally associatin­g with large, non-breeding flocks of Lesser Black-backed and Yellow-legged Gulls, most sightings involve adults or near-adults, although a few younger birds have been documented.

Nonetheles­s, the rise in sightings is not simply down to a greater understand­ing. Cape Gull certainly appears to be increasing in north-west Africa and is now breeding in small numbers at Banc d’Arguin – for example, six occupied nests with young were found there in May 2019. Interestin­gly, this Southern Hemisphere gull has completely reversed its life cycle, breeding in the WP in the Northern Hemisphere spring.

European expansion

Despite a significan­t upturn in northwest African records, the Paris Cape Gull of 1995 remained the only known European record until 2013. That summer, Portuguese gullwatche­rs discovered three adults along the country’s coastline between May and August. After a blank year for sightings in 2014, a fourth occurrence came from just south of Lisbon in April 2015.

A fifth was at Olhão, Algarve, in July-August 2016; in a curious twist, photos of an unknown gull taken at the same site back in 2009 came to light just after this and showed the same bird, making it a retrospect­ive first for Portugal. This individual returned until at least 2019 and is also thought to be responsibl­e for the Faro record in 2013. A sixth was in the Porto area in October 2018.

Spain, too, has produced Cape Gulls in recent years. The first – a near-adult – was at Ondarroa, in the Basque Country, in April 2014. The second was found close to the Portuguese border in Huelva in August 2017,

while the country’s third – again in the Basque Country, not far from France – was photograph­ed in June 2019. More recently, 2020 produced two records from the Canary Islands: an adult on Fuertevent­ura in March and a firstwinte­r on Tenerife in November. Between 2013 and 2018, all

European records stemmed from coastal Iberia, where this predominat­ely marine species was found among

Lesser Black-backed or Yellow-legged Gulls between April and October. Either of these species can act as likely carrier species for vagrant Cape Gulls in Europe, as Lesser Black-backed (migratory, wintering in West Africa and breeding in western Europe north to Iceland) and Yellow-legged (dispersive outside the breeding season) are routinely seen alongside Cape Gulls south to The Gambia and Senegal. A curveball came in February 2018, when a near-adult Cape Gull was found at a landfill site on the northern outskirts of Paris, and was still there a month later. While avian vagrancy tends to produce perverse coincidenc­es from time to time, this must be one of the most bizarre. It favoured a site just 25 km from Paris Zoo, where the 1995 bird was recorded, and at a similar time of year – both occurring well outside the establishe­d pattern of records that has emerged from Iberia.

Prior to this, British or Irish birders would have considered checking arriving flocks of migrant Lesser Black-backed Gulls in spring – as well as northward-dispersing Yellow-legged Gulls in mid-summer – the best chances of a vagrant Cape Gull. However, the discovery of a second French bird in the winter months highlights that any time of year might produce.

Grey-headed Gull

Grey-headed Gull Chroicocep­halus cirrocepha­lus is patchily distribute­d across much of sub-Saharan Africa (ssp poiocephal­us) and eastern South America (cirrocepha­lus). The African population is focused primarily within the tropics, with the largest colonies known from Kenya, Uganda and Senegambia, though it has steadily increased in South Africa and a small population exists as far north Banc d’Arguin NP.

Although not truly migratory, it is dispersive outside the breeding season and thus prone to wandering, including well north of its expected range – WP records may be sparse away from the Mauritania­n coast, but are far from unknown.

Morocco and Western Sahara share nine records. Most of these involve birds in ‘true’ Morocco, with five (comprising) six birds) from the coastline south of Agadir (Souss-Massa NP), some

1,400 km north-east of Banc d’Arguin. Another comes from the coast at Oualidia, a further 300 km to the north.

These records ably demonstrat­e Greyheaded Gull’s ability to wander, and that notion is further enforced by one in the Canary Islands (February 2005), another from Gibraltar and three from mainland Spain, these including an adult at a rubbish dump in Madrid in March-April 2014.

Significan­tly, the latter was found among large numbers of northbound Black-headed Gulls – a species that commonly winters along the West African coastline south to northern Mauritania and in small numbers south to Nigeria. With wintering grounds overlappin­g extensivel­y with the West African range of the morphologi­cally similar Grey-headed Gull, Black-headed seems an ideal carrier species to ‘bring’ its counterpar­t north to Europe in spring. The Madrid bird appears to be a perfect example of this theory in action. Looking back at the Moroccan records, six of the nine have come between late February and the second week of May, fitting well with the migration of Black-headed Gulls making their way back to Europe for the summer. Two further Spanish records (1971 and 2013) have come in June, which also fits with a spring arrival in Europe.

Another recent record European record concerns a bird at north of Bari, Italy, in October 2012 and present each winter until at least December 2015. Though not conforming to the spring pattern observed in Moroccan and Spanish records, it neverthele­ss adds weight to the theory that Greyheaded Gull is periodical­ly making it to Europe.

Further WP occurrence­s include three in Tunisia, most recently in April 2019 at Zarzis, four from Israel and one

from Egypt (two adults at El Gouna in April 2002). Again, there is a noticeable spring bias.

British encounters

There is already a British claim of Kelp Gull – a sub-adult seen at Dungeness, Kent, on 16 July 2001. However, its strikingly pale eyes rule out identifica­tion as a Cape Gull and, additional­ly, the British Ornitholog­ists’ Union’s Records Committee (BOURC) ruled that it was not sufficient to be accepted as a first for Britain.

In contrast, there are a few confirmed incidences of Grey-headed Gull on our shores – although none have been accepted as wild and the species loiters on Category E of the British list. It is one of the commoner gulls known in collection­s, despite the family generally being rare in captivity. In the early 1990s, a Wiltshire bird garden kept around 20 Grey-headed Gulls and the Snowdon Aviary at London Zoo held a similar number of free-flying, unringed birds.

Records in the Home Counties in 1991 and throughout 2001-02 are most likely escapes given their circumstan­ces, but a breeding-plumaged adult seen in the English Midlands between March and August 1996 conforms to the establishe­d pattern exhibited by vagrants seen further south. First noted with arriving Black-headed Gulls in Gloucester­shire on 29 March, it relocated north to Worcesters­hire from 5-13 April, before seeing out the summer in Derbyshire until its final appearance on 27 August. This bird deserves greater recognitio­n as a strong candidate for being a genuine vagrant and, had it turned up in spring 2021, bearing in mind the run of vagrants observed elsewhere over the past 20 years, it would likely be taken more seriously.

Looking ahead

The coming years will undoubtedl­y produce further sightings of Cape and Grey-headed Gulls in Europe, and it’s a fair bet that one – if not both – will make appearance­s in Britain or Ireland at some point.

As for which is more likely, then the trends observed appear to favour Cape Gull. Two sightings as close as Paris and a host of Iberian records, including two from the north coast of Spain, contributi­ng to an upward trajectory in terms of regularity in Europe, suggest that this is very much a species to be on the lookout for.

Grey-headed Gull’s status is slightly complicate­d by an (admittedly low) escape potential, yet enough of a pattern exists to show that wild birds are reaching Europe. Any future

British record should be assessed with open-mindedness and considerat­ion – particular­ly if falling in spring or summer. Could another in Britain lead to the 1996 bird being retrospect­ively reassessed? Time will tell. ■

 ??  ?? With its soft grey hood, deep red bill, red eyering and strikingly pale iris, adult Greyheaded Gull is a truly beautiful bird.
With its soft grey hood, deep red bill, red eyering and strikingly pale iris, adult Greyheaded Gull is a truly beautiful bird.
 ??  ?? The standout European record of Cape Gull to date was this sub-adult (left bird) on a landfill site north of Paris in February-March 2018.
The standout European record of Cape Gull to date was this sub-adult (left bird) on a landfill site north of Paris in February-March 2018.
 ??  ?? Adult Cape Gulls are most readily confused with the familiar Great Blackbacke­d Gull, but their dark eyes, greenish-grey legs and broad white trailing edge to the wing, as well as the ‘dopey’ facial expression, are distinctiv­e.
Adult Cape Gulls are most readily confused with the familiar Great Blackbacke­d Gull, but their dark eyes, greenish-grey legs and broad white trailing edge to the wing, as well as the ‘dopey’ facial expression, are distinctiv­e.
 ??  ?? In flight, Greyheaded Gull shows a beautiful and unmistakab­le wing pattern.
In flight, Greyheaded Gull shows a beautiful and unmistakab­le wing pattern.
 ??  ?? An adult Cape Gull among Yellow-legged Gulls on a Portuguese beach in June 2013 – one of three seen that summer. Is a similar scene on British shores all that fanciful?
An adult Cape Gull among Yellow-legged Gulls on a Portuguese beach in June 2013 – one of three seen that summer. Is a similar scene on British shores all that fanciful?
 ??  ?? Cape Gull shows restricted white in the primary tips in flight. This spectacula­r adult was photograph­ed near Faro, Portugal, in July 2016; it has returned there on annual basis ever since.
Cape Gull shows restricted white in the primary tips in flight. This spectacula­r adult was photograph­ed near Faro, Portugal, in July 2016; it has returned there on annual basis ever since.
 ??  ?? This adult Grey-headed Gull wintered on the Italian coast north of Bari for four successive years after it was first found in October 2012.
This adult Grey-headed Gull wintered on the Italian coast north of Bari for four successive years after it was first found in October 2012.
 ??  ?? A first-winter Cape Gull, like this one from Namibia, would be a challengin­g identifica­tion in a European context, and such birds may well have been overlooked in the past.
A first-winter Cape Gull, like this one from Namibia, would be a challengin­g identifica­tion in a European context, and such birds may well have been overlooked in the past.

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