Fulmars, Petrels and Shearwaters - Procellariforms
These are highly pelagic seabirds, spending almost all their lives off-shore and only coming to land to breed, often on remote islands. They are all highly adapted to a life at sea and different species exploit often very narrow ecological niches, leading to very complex taxonomic relationships between species, many of which are still being unravelled.
This complexity, which applies to several groups of seabirds in the North East Atlantic, has implications for our understanding of their conservation status; species with only very small populations are highly vulnerable to even small changes in their environment.
Recent developments in genetic research have allowed a new and much more scientific approach to understanding seabird species. The following groups of pelagic seabirds in the northern Atlantic are being reviewed by scientists, leading to new species being revealed or proposed (even if only proposed, it is crucial that their conservation status is secure):
Fea's petrel group: long thought be a single species breeding in the north and south Atlantic, we now know that there are three or possibly four species; two or three of which breed in the north Atlantic: Zino's petrel on Madeira, Bugio Petrel on the Desertas near Madeira, and Fea's Petrel breeding on the Cape Verde islands.
Manx Shearwater group: originally considered to be one species with one race in the north Atlantic and two in the Mediterranean Sea. It is now accepted that these are three separate species; of which, the Balearic Shearwater is regarded as critically endangered (see below).
Cory's Shearwater group: also formerly thought to be one species, but analysis of DNA and vocalisations prove it to be three; two, Cory's and Cape Verde, breed in the Atlantic and one, Scopoli's, in the Mediterranean.
Little Shearwater group: this is a very complex group, formerly considered to be one species distributed in both the north Atlantic and the southern Oceans. It is now clear that there are several species, and it seems likely that three species breed in the north Atlantic, although definitive separation awaits. Of these, Baroli's Shearwater, which breeds on Madeira, Canaries, and Azores, visits our area.
Madeiran storm petrels: until very recently Madeiran Storm Petrel of the north Atlantic and Band-rumped Storm Petrel of the Pacific were thought to be one species. However, new research not only shows they are separate species, but, suggests that there are at least two, and maybe up to four species in the north Atlantic. One of which, Monteiro's Storm Petrel is very vulnerable as it is only known from two tiny islets in the Azores and numbers only c200 pairs.
European storm petrels: there is increasing evidence that birds breeding in the Mediterranean are a distinct species from the main population in the north Atlantic, although this has not yet been proven.
Most species of procellariforms (tubenoses) only come ashore to incubate eggs or feed young. Most are very ungainly and slow on land so are vulnerable to predation by gulls and skuas, or by introduced mammals like rats and cats, and are now often limited to nesting on the most inaccessible, remote, predator free islands.
Identification to species can be very hard, even for experienced observers. Understanding the flight action of petrels and shearwaters is often crucial to identifying them, especially in bad light or at distance when distinctive plumage features are not easily discerned.
Waders (or shorebirds)
A number of wader species are quite common migrants at sea through Biscay and the Channel, sometimes quite far offshore, as they migrate in spring and autumn (effectively anytime from April to November), often traveling in flocks.
The Grey (aka Red) Phalarope is a specialist highly pelagic wader that migrates and winters well out to sea, and as such is covered here.
Skuas - Stercorariidae
Skuas are structurally similar to gulls but are not closely related. Four of the seven species of skua occur in western European waters; Great Skua, Pomarine Skua, Arctic Skua and Long-tailed Skua. They all have a powerful flight and piratical (klepto-parasitic) habits, harrying other seabirds until they disgorge fish they have caught.
All four species occurring in the area breed in higher latitudes and migrate through our waters in spring and autumn. Some Great Skuas also stay to winter.
Although the skuas appear to be in two distinct groups based on appearance, with Great Skua together with the three southern hemisphere species in one group (formerly the Chatheracta skuas), and the smaller northern skuas in the other group (the Stercorarius skuas (known as Jaegers in North America)), genetic research concludes that the picture is more complex, and the Pomarine Skua is more closely related to the Great Skua than it is to the other two Stercorarius skuas. Hence, most authorities have abandoned the separation and call them all Stercorarius skuas, at least until the picture becomes clearer!
Gulls - Laridae
The taxonomy of gulls is highly complex, and much remains to be resolved. Several species are still being reviewed by scientists to determine their true status. It is only recently that the Yellow-legged Gull that frequents northern Spanish shores was separated (split) from the Herring Gull of more northerly latitudes.
Only a few gulls are highly pelagic, ie spend much of their lives at sea, but most are largely tied to the sea in that they breed and forage on the coast. The larger gulls are generalists that will exploit any food source available, and this often causes them to predate on other wildlife, including seabirds, which in some cases can cause major conservation problems, particularly where their populations are artificially high due to exploiting fisheries' waste or rubbish dumps.
For identification purposes, gulls may be divided into two groups; large and small, although a few might be described as medium sized! And, gulls are prone to vagrancy, particularly from North America.
Gulls occurring regularly in western European waters:
Large: Greater Black-backed Gull, Lesser Black-backed Gull, Herring Gull, Yellow-legged Gull, Common Gull
Small: Black-headed Gull, Mediterranean Gull, Kittiwake, Sabine's Gull, Little Gull
Although generally similar in appearance, which presents identification challenges at sea, and having similar ecologies, terns utilise the marine environment in subtly different ways. They often specialise in specific prey caught in particular parts of the marine environment eg inshore or offshore, warm or cold waters and so on.
One thing they have in common is that they nest colonially on offshore islets and on undisturbed areas of beach. They are vulnerable to disturbance and to predation, so shift their nest sites every few years, however where space and opportunities for new colonies is limited they are forced to stay put, and so become easy targets for predators like gulls, rats or foxes.
All species migrate prodigious distances for such small and light-weight species. Most species migrate from high latitudes to the equator, but many Arctic terns migrate from the Arctic to the Antarctic, a journey of 12,000 miles (20,000 km), and as they are long-lived, often exceeding 20 years, they can travel 500,000 miles in migration alone, and research with data-loggers shows that in total they can fly over 1.5 million miles in a lifetime.
Our area is at the southern end of the distribution of the auks. Here, where waters are warmer, they occur at low densities, but further north in cold waters they breed in enormous numbers. However, they are particularly vulnerable to a range of environmental threats. They are the group of seabirds to be worst affected by oil spills as they spend much of their time sitting on the sea. They are also prone to changes in fish stocks, and starvation events are not unknown when for example sand eels are over harvested from the northern North Sea.