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Caution
• Gull identification and taxonomy is at a very fluid stage.
• Some of the terminology used here may not endure.
• But much new knowledge is being obtained and refined.
At one time -- large gulls were simple
All were Sea Gulls Conil, Spain June 2002
4 taxon here!
First Advance
• Herring Gull Larus argentatus
• Lesser Black-backed Gull Larus fuscus
• Great Black-backed Gull Larus marinus
Herring Gull adult Larus argentatus argenteus - SW
England, April 2002
Herring Gull adult Larus argentatus argenteus - SW
England, April 2002
Herring Gull adult Larus argentatus argenteus - SW England, August 2001
Great Black-backed Gull adult Larus marinus -- Seahouses, Sept
1991
Lesser Black-backed Gull adult Larus fuscus graellsii -- Seahouses, April 1992
Glaucous Gull adult Larus hyperboreus -- Seahouses, Sept
1990
Iceland Gull second-winter Larus glaucoides -- SW England, April
1990
Then races /forms appeared• Herring Gull:
– argenteus (France, Britain, Belgium, Holland)– nominate argentatus (Scandinavia)– smithsonianus (North America)
• Lesser Black-backed Gull– graellsii (Britain, France)– intermedius (S and W Scandinavia)– fuscus (N and E Scandinavia)
• Great Black-backed Gull– monotypic (one form)
Lesser Black-backed Gull adult Larus
fuscus graellsii -- Holland, May 1999
Lesser Black-backed Gull adult Larus fuscus graellsii/intermedius -- Holland, May 1999
Lesser Black-backed Gull Larus fuscus intermedius -- Bergen, Norway, May 1997
Finland for some!
Finland IGM 6: Tampere Tip, August 2002
Tampere Tip, Finland, August 2002
Lesser Black-backed Gull adult Larus fuscus fuscus -- Tampere tip, Finland, August 2002
BalticGull
Heuglin’s Gull adult Larus heuglini -- Tampere tip, Finland, August 2002
Heuglin’s Gull adult Larus heuglini -- Tampere tip, Finland, August 2002
Herring Gull Larus argentatus argenteus -- Seahouses, Sept 1991
Herring Gull Larus argentatus argentatus/argenteus -- Texel, Holland, May 1999
Herring Gull Larus argentatus argentatus -- Tampere Tip, Finland, August 2002
Herring Gull Larus argentatus argentatus -- Tampere Tip, Finland, August 2002
omissus
Herring Gull Larus argentatus argentatus -- Tampere Tip, Finland, August 2002
omissus
PJ Grant: Gulls - a Guide to Identification 1986
11 taxon
‘Southern Herring Gulls’
• Increasingly classified as new species. – Caspian Gull Larus cachinnans– Mediterranean Yellow-legged Gull Larus
michahellis– Atlantic Yellow-legged Gull Larus atlantis --
regarded as race of michahellis in some recent studies
Locations Visited
• From 1990-2002:– Canaries (every one)– Madeira– Morocco (North and South)– Portugal (all coasts)– Spain (Andalucia, Galicia, Santander)– France (SW)
• Mainly March -September
Map for Canary Islands
Agadir, Morocco (roof top colony, Amadil Hotel)
Classification of YLG - Leg Colour: YL yellow legs
Mediterranean Yellow-legged Gull adult Larus michahellis, Royan, SW France, August 1991
Caspian Gull first-winter Larus cachinnans, Norway, February 2001 (Frode Falkenberg)
Atlantic Yellow-legged Gull adult Larus atlantis, Lanzarote, Canaries, August 1992
Atlantic Yellow-legged Gull adult Larus atlantis, Agadir, Morocco, April 2000
Atlantic Yellow-legged Gull adult (two) Larus atlantis, Porto, Portugal, March 2001
Cantabrican Atlantic Yellow-legged Gull third-summer Larus atlantis/argentatus??, Noja,
Santander, Spain, August 1990
Classification - Mantle Shade: cf michahellis: S same, D darker, P paler
Classification - Size: cf michahellis: S same, Less smaller
Size comparison:
• Compared to michahellis:
• atlantis is: 5.8% shorter in wing;
4.6% shorter in tail;
8.2% shorter in bill length;
10.0% shorter in tarsus;
11.3% shorter in toe.
Typical Adult Wingtip, Atlantic Yellow-legged Gull Larus atlantis, Agadir, April 2000
Typical Adult Wingtip, Atlantic Yellow-legged Gull Larus atlantis, Fuerteventura, April 2000
Two Adult Atlantic Yellow-legged Gull, Larus atlantis, Setubal, Portugal, March 1999
Adult Atlantic Yellow-legged Gull, Larus atlantis, Minho, Portugal/Spain (Galicia) border, April 2001
Classification - Wingtip: MWMB much white & much black, LWMB less white & much black (>=80% solid
black triangle, <=30% mirror P9), MWLB much white & less black
Classification - Calls (long): A like argenteus (possibly deeper), M like michahellis, SG like shrill graellsii,
AM even argenteus & shrill graellsii
Proposed Forms of atlantis -- NR
Genetic Studies
• Liebers, D, Helbig, A J, and de Knijff, P, Genetic differentiation and phylogeography of gulls in the Larus cachinnans-fuscus group (Aves: Charadriiformes), Molecular Ecology 10 2447-2462 (2001).
• michahellis is derived from atlantis as the older lineage.
• atlantis has held a large population over a long period, residing in an area of relative climatic stability.
Differentiations found
• michahellis population is less diverse than atlantis
• Significant differentiation within all five atlantis colonies analysed.
• Unexpected differentiation was found between:• northern atlantis (Azores, west Portugal and
Galicia) and southern atlantis (Madeira, Morocco).
Classification - Forms (Liebers): MM michahellis, SA southern atlantis, NA northern atlantis. Samples came
from sites in green. Notes: extension (by NR) to Canaries needs to be
confirmed; Cantabrican omitted from study.
Atlantic Yellow-legged Gull Larus atlantis - Mauritania, Azores; Kelp Gull (Birding World)
The Atlantic-Mediterranean Intersection Zone
Three main forms in Zone
• Mediterranean Yellow-legged Gulls michahellis– marshes, lagoons and marismas
• Atlantic Yellow-legged Gulls atlantis– harbours and rocky cliffs in west Andalucia at Cádiz
and Barbate and south-west of Tanger at Asilah
• Intersection Mediterranean/Atlantic Yellow-legged Gulls michahellis/atlantis– harbours and rocky cliffs in the immediate west, centre
and east of area
michahellis habitat - near Sanlúcar
michahellis habitat - near Barbate
michahellis habitat - near Conil
michahellis - Conil August 2001 (with LBBG intermedius/graellsii, Audouin’s)
Conil, August 2001: One atlantis (front) with five michahellis
michahellis distribution: within red line in marismas
Cliffs at Barbate
Cliffs at Barbate 2
Two Iberian atlantis at Barbate, June 2002
Two Iberian atlantis at Barbate
Adult Iberian atlantis at Barbate, June 2002
Adult Iberian atlantis at Barbate, June 2002
YLG distribution: michahellis: red line in marismas; atlantis: blue line on cliffs
Intersection michahellis/atlantis
• In harbours and rocky cliffs in the immediate west, centre and east of area:– some characteristics of Iberian atlantis– increasing tendency to Mediterranean form
Tarifa michahellis/atlantis, second-summer, June 2002
Tarifa michahellis/atlantis adult, June 2002
atlantis wingtip
Tarifa michahellis/atlantis adult, August 2001
Estepona michahellis/atlantis 1s/2w (juv, 1s, adult), August
2001
Estepona michahellis/atlantis 2s-3w, August 2001
Estepona michahellis/atlantis, third-summer, June 2002
Estepona michahellis/atlantis 2s, June 2002
YLG distribution: michahellis: red line in
marismas; atlantis: blue line on cliffs; intersection: yellow line on cliffs
Width of Intersection Zone
• Barbate 40km W of Straits of Gibraltar
• Nerja 170km E of Straits of Gibraltar
• Does not appear to be greater than 210km.
• May be less if assess coastline more completely for colonies
Comparison of SW Spain and SW France (Yésou)
• michahellis are invading both areas and breeding in a particular biotope (marismas, lagoons, salinas)
• Iberian atlantis in Spain appear to occupy a similar role to the argenteus in France, breeding on cliffs, islands and forts in SW Spain
• additional complication in SW Spain is the potential gene mixing zone across the Straits
Four Taxon at Conil, June 2002
LBBG intermedius michahellis Audouin’satlantis/michahellis
Work of Dwight
• Jonathan Dwight, an American, studied skins of gulls from all over the world.
• Dwight, J, (1922), Description of a new race of the Lesser Black-backed Gull, from the Azores, Am. Mus. Novitates, 44: 1-2.
• Dwight, J, (1925), The Gulls (Laridae) of the World: their Plumages, Moults, Variations, Relationships and Distribution, Bull. Amer. Mus. Nat. Hist. 52: 63-401. In NHS library
Dwight
• First proposed atlantis (1922) as new taxon as race of LBBG -- Azorean LBBG -- based on studies of Azores and Canary specimens.
• Recently some workers have been claiming ‘true atlantis’ is only present on the Azores and actually basing whole classifications on this quoting Dwight as authority.
Dwight -- Extract from 1925 paper - range of atlantis
Lessons
• Read original texts before quoting from them.• Range of Dwight’s atlantis is very close to
that of Southern atlantis derived in present study and in the genetic study of Liebers.
• Dwight’s work was very systematic -- pioneering painstaking approach.
• He also noted wingtip pattern of michahellis in extreme W was like atlantis
So how many species?• Not settled but genetic and morphological studies are indicating
a number of splits.• Most of the former Herring Gull races are emerging as new
species (not argenteus though). • LBBG forms count only as one species. • Identification is another problem.• Many differ at the population level but individuals cannot be
identified with certain.• Problems of intersection areas. • Current research concentrating on birds of known origin
(colonies, ringing).
