Birds of the
English Channel & Bay of Biscay

Black Browed Albatross, an extreme rarity from the South Atlantic,
was recorded in the Bay of Biscay on BDRP surveys in October 1999.

The Specialists

Although it is possible to see almost anything along the survey route given luck, the right weather and suspension of disbelief, this section will concentrate on the birds which rely on the marine habitat for their survival. Although there are species of land bird which make ‘landfall’ on the ship and others such as waders and wildfowl which are regularly seen on migration through the area, these are not birds which depend on this habitat.

Seabirds are a group of birds which are pelagic in nature. This means they spend most of their time at sea and only come to land to nest and rear young. This can make them difficult to observe, especially when many species choose remote offshore islands for their procreation and many only come to their nest sites at night, spending all day gathering food at sea. For many British seabird enthusiasts, their only chance to catch a glimpse of some of the species which occur regularly in the bay is to spend many hours staring out to sea from some remote headland in Cornwall or on the west coast of Ireland.

For many bird watchers the sea is the great frontier, the last uncharted territory that needs to be explored. We currently know so little about the habits and distribution of so many North Atlantic species of seabird that every trip into an area such as the Bay of Biscay is a voyage of discovery. We hope that you can contribute.

^^ top

Fulmars, Petrels and Shearwaters (Procellaridae)

This is the group of birds which most exemplifies what is so special about the Bay of Biscay. They are all highly pelagic. They come to land only to breed and rear young. They are all designed for life on the ocean wave.

Great Shearwater
The larger species have long, pointed wings ideal for gliding flight. Like Albatrosses or our own Northern Gannet, Shearwaters and larger petrels such as the Fulmar use a style of flight which takes advantage of the wind differential between wave troughs and the air above. This manner of flight is often known as ‘shearing’ and involves a switch-backing action which alternately shows the birds underside then upperside. In very light winds, birds will not cover large distances and may find it difficult to fly without expending a lot of energy flapping their wings.

The smaller species of petrels have shorter wings and flap more than the larger species although many have rather stiff wing beats like those of their larger relatives. Most of the species employ some ‘shearing’ or gliding flight although this is always interspersed with some wing action.

The flight action of petrels and Shearwaters is often crucial to their identification especially in bad light or at distance when distinctive plumage features cannot be seen. For experienced seabird watchers the flight is often the first and most important clue to a successful identification.

Most of the species are pelagic by day and return to their nesting sites by night when they may be vulnerable to predators due to their lack of adaptation to the habitat. This is one reason why so many nest on remote islands away from predators such as foxes. On islands where unnatural predators, such as cats, have been introduced the consequences can be devastating.

^^ top

Cory’s Shearwater - Calonectris diomedea

World Distribution:

Cory’s Shearwaters nest colonially in burrows, usually on offshore, rocky islands in the North-East Atlantic or Mediterranean Sea. Away from their nesting sites they are pelagic. The nominate race C. d. diomedae nests in the Mediterranean Sea and the Atlantic race C. d. borealis on various islands between around 15° N - 40° N. Birds are present in the breeding areas from late February until October-November when southbound trans-equatorial dispersal begins from all colonies to wintering grounds in the South Atlantic, mainly off the coast of southern Africa and round into the western Indian Ocean. Non-breeding birds are known to disperse across the Atlantic where they are found off the eastern coastline of North America in good numbers July-October. Birds are rarely seen north of Irish waters and are rarely found in waters of temperature <13° C.

Survey Area Distribution.

One of the speciality species of Biscay. In the late summer and autumn they can sometimes be seen in large numbers, especially around the northern Celtic-Biscay shelf edge. They are rarely seen north of about 48° N with peak numbers between 46° N and 47° N. They are also found in quite high numbers throughout the deeper waters of the abyssal plain south to the Cap Breton canyon.
This species often forms rafts of hundreds or even thousands of birds, usually associating with Great Shearwaters or other species such as Northern Gannet and other Shearwaters. They are not merely migrants through the area as they are in many parts of their known range, spending (we assume) a significant part of the year here.
Cory’s Shearwater is scarce in the spring months, although they have been recorded in March and April.They can be found in low numbers in June-July before the main arrival commences usually in the second half of August. Numbers drop off during September-October with less than 1% of BDRP records during the latter month.
There is evidence to show that there is a sizeable moulting population from the Mediterranean which moves north into the shallower inshore waters of the Bay of Biscay during May-June. They then disperse in August, when they appear in the study area in large numbers. They seem likely to be the same birds, although there is no proof of this. These are presumably non-breeding birds, dispersing early from the Mediterranean or Atlantic breeding colonies and taking advantage of the rich food sources available in the Bay of Biscay.
Large numbers of migratory birds pass the Galician coast (NW Spain) during August-November with a peak in October, reflecting the trends our records show.
It is not known whether the birds we are seeing are of the race C. d. diomedea or C. d. borealis because of the difficulty of separating these races at sea. There are currently no records of ‘Cape Verde Shearwater’ C. d. edwardsii in Biscay, although there was a claim of five birds in July 2000, which may prove to be the first record for the area. It is certainly possible that they do occur, considering their breeding range and the lack of current knowledge concerning their post-breeding dispersal. Most records in the winter have been off coastal Africa in a similar latitude to their breeding sites. Cape Verde Shearwater has been muted as a possible ‘split’ from Cory’s Shearwater because of morphological differences.

Identification: Structure and flight

This is a large, heavy Shearwater which is similar in size to Great Shearwater or a Lesser Black-backed Gull. The flight can be distinctive although this depends very much on the strength of the wind. In comparison with Great, it usually appears to have more flexible wings which are often bowed. It flaps infrequently and glides, even in calm conditions on more angled wings than Great. It often circles in calm conditions and drifts appearing to be rather directionless unlike the more direct flight of Great Shearwater.
Cory’s habitually fly in tight circles in calm conditions when looking for food. Great Shearwater never seems to adopt this type of flight. In stronger winds, birds rarely flap and often bank very high into the wind at great height, before plunging back down into wave troughs. Cory’s usually feeds on the wing by picking food from the surface or plunge-diving from less than 10 metres. They usually spend little time underwater as they are not very adept swimmers.

Identification: Plumage

The plumage of Cory’s Shearwater is rather drab, especially at long range when they can appear to lack any identifying features. At close range however, they look very different. They have a large, rather thick pale yellowish bill with a dark, diffuse sub terminal band. The head is distinctly hooded in appearance due to an extensive wash of brown over the breast sides and head. The upperparts are distinctly scaly in appearance, especially on the back and uppertail and there is a distinctive darker saddle of feathering over the mantle, tertials, upperwing coverts and primaries. There is often some white on the uppertail though never as extensive as on Great Shearwater. The underparts are usually clean whitish with thin dark edges to the secondaries and broader dark edges to the primaries on the underwing.
The race C. d. edwardsii or Cape Verde Shearwater, is quite distinctive when seen well. They have an all dark and rather slim bill, darker head and upperparts. The flight has been described as rather more typically Shearwater like than other races of Cory’s, with stiffer and more rapid wing beats.

^^ top

Great Shearwater - Puffinus gravis

World distribution:

Great Shearwater is a fascinating species of bird. A true wanderer, they nest in the south Atlantic on just four islands, principally on the Tristan da Cunha Group at approximately latitude 37° S where c.2,000,000 pairs nest between September and April-May.
They are trans-equatorial migrants; migrating north April-June before congregating in offshore waters off eastern North America, June-August. Most breeding birds are back at their colonies by September.
In the survey area the peak numbers are seen August-October and it is likely that most, if not all birds are non/pre-breeders which follow the prevailing westerly winds to feed in zones of nutrient up-welling in the Bay of Biscay, without moulting. It is also likely that most breeding birds return to the South Atlantic through a direct mid-ocean route, which may explain why numbers in the NE Atlantic are substantially lower than those in North American waters June-August, where most adults spend the ‘winter’ months.

Survey Area Distribution:

Great Shearwater has been recorded from July-November by the BDRP. Less than 1% have been recorded in July with the highest numbers being seen in August and September. However, large numbers can still be present in late October, as in 2000 when birds arrived later than the previous year.
Birds often congregate in large numbers, with flocks of up to a thousand birds recorded and are clearly feeding in the area rather than migrating through it. The largest numbers occur in deep water areas (>1000m) between latitudes 44° N and 47° N and also in zones of nutrient upwelling north of the Celtic-Biscay shelf edge, over shallower water. Birds are usually distributed evenly over deeper water, implying their reliance on shelf.
Some years, however, there are few birds seen in the area and it seems likely that years with a prevailing westerly airflow may encourage birds to feed in more sheltered, shelf-edge waters where either food is easier to find or conditions are more hospitable.
Although the Bay of Biscay seems to be the most important site for this species in European waters it is possible that they also occur in high densities off the Irish shelf edge. This is indicated by sporadic high numbers seen from coastal watch points, such as Cape Clear. However, dedicated surveys in these areas have not produced high densities. They are certainly infrequently recorded north of latitude 55° N, except in the waters off south-east Greenland. It is probable that large numbers also occur off the shelf edge around north-west Spain where birds are regularly reported during north-west winds off Galicia with up to 3000 recorded in a day, mainly September-October.

Identification: Structure and flight

The main confusion species for Great Shearwater is Cory’s although it is possible, because of their different manner of flight, to confuse Great with other smaller species of Shearwater or Fulmar. The flight of Great is typically more stiff winged and direct than Cory’s on rather straighter and less bowed wings. Although they often glide like Cory’s, in high, bounding arcs over the sea they rarely circle and their wing beats are faster and more frequent between the glides. When feeding, Great tends to patter energetically along the surface of the water to chase fish or can plunge dive from a height of no more than a metre or so. Feeding is often undertaken in large groups and may be mainly nocturnal because of their liking for squid which tend to come to the surface at dusk.

Identification: Plumage

The plumage is the most reliable guide to identification. Great has several features which are often visible, even at long range. They have a slimmer, darker bill than Cory’s. A distinct dark cap is usually visible which is accentuated by a clear white collar around the hind neck. They have a white band at the top of the tail/base of the rump which is more defined than on Cory’s. There is usually less contrast between the colouration of the back and the dark saddle across the upperwing (which both species show) than on Cory’s. Another distinction, which is of less use on distant birds, is that Great Shearwaters have darker markings on the underparts, specifically on the shoulder, on the belly and some dark spots or bars on the inner underwing.

^^ top

Little Shearwater - Puffinus assimilis

World Distribution:

In the North Atlantic probably under 10,000 pairs breed on the Azores, Canary Islands, Madeira and Cape Verde Islands. They have a fragmented but fairly widespread distribution in the southern hemisphere. It seems that Little Shearwater does not tend to wander far from its breeding grounds, which accounts for their high degree of subspeciation worldwide. However in recent years they have occurred with increasing regularity further afield. There have been sightings off the eastern seaboard of the United States and they are seen annually off the coast of Britain and Ireland. The race which occurs regularly in Biscay is P. a. baroli, but there is a recent claim of P. a. boydi, the Cape Verde race.

Survey area distribution:

Little Shearwater is one of the most highly prized species for bird watchers who come to Biscay in the late summer and autumn. In Biscay, birds are seen regularly but in small numbers, during the months of July-October. During August, the peak month, some observers have been lucky enough to see 15-20 in a single trip. They are usually encountered south of the northern celtic shelf edge. The records from Biscay mark an extension of the known dispersal range of this species. Perhaps they take advantage of the rich feeding this area offers during the late summer months before moving back south for the winter.

Identification:Structure and flight:

When seen well, Little Shearwater is very distinctive. The general rule is: if there is any doubt in your mind then it wasn't a Little. The flight is the main clue. It usually follows a series of short, shallow and rapid wing beats with a short glide where its wings are held flat or parallel to the water’s surface. Only in high winds, does Little Shearwater noticeably bank into the wind and they rarely, if ever, take a switch-backing course. Due to their compact body shape and rather short outer wing with noticeably rounded wing tips they can appear almost like auks although they do not really fly like them. Another comparison which is often mentioned and can be useful for identification is to the flight of a Common Sandpiper, with their flicking wing beats and short glides with wings held flat.

Identification:Plumage:

The plumage is similar to Manx Shearwater, being basically black above and white below. The upperwing, however, usually has a distinctive pale panel of greyish feathering on the secondaries and greater coverts, the latter sometimes being tipped with white. P. a. baroli has a very different head pattern to Manx. It has a defined dark cap which doesn’t reach the eye leaving a white supercilium and white ear coverts. This makes the dark eye stand out from the rest of the face. With P. a. boydi on the other hand, the cap does reach down to the eye, like with Manx Shearwater. Also, this subspecies, which has been seen in Biscay, has dark undertail coverts, and more extensive dark on the trailing edge of the underwing.

^^ top

Manx Shearwater - Puffinus Puffinus

World Distribution:

This is a species which breeds in the NE Atlantic and winters further south, mainly off the coast of South America but also in a band, east to west, across to the South African coast. Approximately 94% of the world population breeds around the western coasts of Britain and Ireland in often large colonies, principally off the west coast of Scotland, the Celtic Sea, waters off south-west Wales and around the Irish Sea front. Most of their activity is nocturnal, spending daylight hours out to sea. They arrive late March-May and disperse mainly August-October.

Survey Area Distribution:

They are seen mainly from late March - November, although they have been recorded in winter. Most birds are seen in Spring north of 48° N in the south-western approaches and English Channel. They are quite scarce further south and are usually seen singly during the summer and early autumn. It seems likely that migrant Manx Shearwaters head straight to wintering grounds without passing through the area in any numbers. It seems likely that birds which have been observed in the deeper waters of the bay itself are either adults, roaming widely in the spring and summer or young birds in the autumn.

Identification:Structure and flight:

The main confusion species is Little Shearwater, although they can be difficult to tell from Sooty, or even Great Shearwater, at long distance. In flight they tend to follow a short and rapid (though not fluttery) series of wing beats with banking flight in and out of wave troughs. In high winds they may not flap at all and bank high over the wave tops. In light winds this pattern of flight becomes less accentuated, with more flapping and less banking. The wings are always held quite stiff and straight, although slightly down-turned.

Plumage:

They are uniformly blackish on the upperparts and upperwing although they can look brownish in strong sunlight (beware Yelkouan Shearwater). They have a dark cap which extends down to the level of the eye. The underparts are white, including the undertail coverts and the underwings which occasionally show dark marks on the armpits, and lower underwing. The primaries and secondaries on the underwing are largely blackish, more so than in Little Shearwater of the race P. a. baroli but similar to P. a. boydi.

^^ top

Sooty Shearwater - Puffinus griseus

World Distribution:

Sooty Shearwater is another trans-equatorial migrant. They breed in large numbers in the South Pacific, mainly around New Zealand and southern South America. The only known breeding sites in the south Atlantic are in the Cape Horn region and the Falkland Islands.
Most South American birds migrate north up the coast of the western United States where they can be found in flocks of several million birds. Some migrate up the eastern coast of South America and into North American waters by June. Here they are usually outnumbered by Great Shearwaters by 100:1. Some then head east across the Atlantic to European waters where they can be seen from July through to November. They can be seen from all coasts of Great Britain and Ireland.
The largest numbers are usually seen off the western coast of Ireland in September but they can also be seen in their hundreds in the North Sea. It has been suggested that that all North Atlantic birds are non/pre breeders, and that most (if not all) adults head north into the Pacific. This theory partly explains the disparity between records of Great and Sooty Shearwaters on either side of the Atlantic.

Survey Area Distribution:

In the survey area, Sooty Shearwaters occur in low numbers throughout during the autumn months, particularly in September. They are slightly commoner around the northern Celtic-Biscay shelf edge and around the southern canyons where they can often be found in amongst rafts of Great and Cory’s. They are also frequently seen in the English Channel having presumably migrated through the North Sea. They seem to prefer colder waters for feeding as the main concentrations in the NW Atlantic are further north e.g. Rockall Bank and the Faeroese fishing grounds. Although they are never common and are usually found in ones and twos, it is possible to see around 50 in a trip.

Identification: Flight and Structure:

Sooty Shearwater has a very distinctive flight silhouette and action which enables identification at long range. It is a rather large and powerful Shearwater with a strong, fast and direct flight. The body is quite long and slim but it can appear rather fat due to the relatively long, straight and thin wings. The wings are held slightly swept back at the hand, especially in strong winds. The flight is typical of a Shearwater with a few short wing beats followed by a long glide and banking, the height and frequency of which depends largely on wind conditions.

Plumage:

The body and head are all dark as are the upperwings, although they can be paler on the outer secondaries and inner primaries. The underwings have a pronounced paler, almost silvery, central area with can vary a little in size but always includes the underwing coverts and usually the inner flight feathers. The armpit of the wing is often darker. The visible extent of this paler area depends very much on the light, the angle and the distance of the bird to the observer. In dull light and at great distance, the underwing may appear all dark.
The main confusion species in the bay is Mediterranean Shearwater of the race P.y.mauretanicus. For an account of the main differences please read below.

^^ top

Mediterranean Shearwater - Puffinus yelkouan

World Distribution:

Closely related to Manx Shearwater but no longer considered the same species. Mediterranean Shearwater, as its name suggests, breeds exclusively in the Mediterranean Sea where it also winters. There are two races of Mediterranean Shearwater P.y.mauretanicus and P.y.yelkouan. They are currently the subject of genetic research which may result in the splitting of these races into two species, indeed some authors already consider them as such.
The former breeds in the western Med., largely in the Balearic island chain, and the latter east of around Corsica. The Balearic race undergoes a post-breeding dispersal into the North Atlantic in the late summer and autumn, with thousands of birds moulting in inshore waters in the Bay of Biscay from June-October with gradual northward dispersal taking significant numbers of birds into British waters, particularly the English Channel, during the late summer. The Yelkouan race is less well known, partly because of identification difficulties, but is known to disperse mainly north and east to areas such as the Adriatic, Aegean and Black Seas. There is thought to be some westbound movement also but there are as yet no accepted records for Atlantic waters despite several claims.

Survey Area Distribution:

There are no confirmed records of Yelkouan type Shearwaters in the Bay of Biscay although there have been claims of birds in the past. Four birds were seen and videotaped in the southern bay in August 2000 and may prove to be the first confirmed records for the Atlantic.
Balearic Shearwater are recorded in small numbers throughout the survey area although there does seem to be a peak around the Cap Breton canyon in the southern bay. The peak period is during June-November with 95% of BDRP records being during this period. Considering their breeding habits and preference to moulting in the shallow coastal strip between Vendee and the Mor Braz area of Brittany during the summer months they do not seem especially well suited to deep water areas.

Identification: Flight and Structure:

The flight of this species is largely similar to Manx Shearwater. The Balearic race is noticeably larger however, often by some 15%. Yelkouan is closer in size to Manx. Both share a rather pot-bellied and bulky appearance compared to Manx although this is apparently less pronounced with Yelkouan, due to its smaller size. They also tend to have a longer neck and shorter tail than Manx and the toes project slightly beyond the tail, unlike Manx. They are noticeably smaller than Sooty Shearwater with slightly broader and more rounded wings and a more pot-bellied appearance. The wings are not as angled as Sooty in typical flight, which is similar to Manx.

Plumage:

The plumage is highly variable. P.y.mauretanicus is browner above than Manx, although warmth of colouration varies between individual birds and depends very much on the light. On the underparts, the sides of the breast, undertail coverts and vent usually show some brownish colouration.
Some may be closer to Manx and some may even approach Sooty Shearwater in basic colouration, although they are never all dark on the head and body. There is often some dark colouration or dark spots on the underwing, usually on the armpit.
P.y.yelkouan is very difficult to identify with any certainty. Paler birds are very similar to Manx Shearwater with pale underparts and underwing. However, crucially they can be told from Manx by the presence of Balearic type features on the underparts and underwing, notably and typically dusky undertail coverts, dusky -washed axillaries and sometimes a diagonal bar across the underwing which Manx can show but Balearic rarely does, except on very pale individuals. There may also be some shading on the flanks.
The colouration of the upperparts and upperwing is distinct from Manx as they always shows a brownish cast. However, Manx can appear to have similar colouration in strong sunlight, or on worn birds. Darker birds are probably indistinguishable from P.y.mauretanicus. They may prove to be virtually indistinguishable at sea.

^^ top

page 2 >>