European Storm-Petrel

The storm petrel is a small bird, 14–18 cm (5.5–7.1 in) in length with a 36–39 cm (14–15 in) wingspan. It weighs 20–38 g (0.71–1.34 oz), with an average of 28 g (0.99 oz). It is square-tailed and has all-black plumage except for a snow-white rump that extends to the sides of the tail base and a broad white band on the under wings. Juveniles in fresh plumage can also show a narrow white bar on the upper wing. The plumage becomes dark brown rather than black as it becomes worn. No obvious differences between the sexes are seen, although in the Mediterranean subspecies, at least, most captured birds can be sexed using a formula which involves multiplying the wing length by the length of the white rump band; females are slightly larger and have a longer white rump than males. The Mediterranean subspecies has longer wings and a heavier bill on average than the nominate form, but neither sex nor subspecies can be determined by observation at sea. Moult is prolonged in all tubenoses, since they must maintain an ability to fly. Northern populations start replacing their plumage after those further south, reflecting the later start to their breeding season. Birds in a Welsh colony commenced moulting in early August, while populations in northern Spain and the Balearics started in early July and mid-June, respectively. …

Storm petrels breed only in the Western Palaearctic on islands off the Atlantic and Mediterranean coasts of Europe. The largest colonies are in the Faroe Islands (150,000–400,000 pairs), United Kingdom (20,000–150,000), Ireland (50,000–100,000), and Iceland (50,000–100,000), with smaller breeding areas off Norway, Malta, Spain, the Canary Islands, Italy, France, and Greece. The strongholds of the H. p. melitensis subspecies are the islands of Filfla (Malta), Sicily, and the Balearic Islands, with smaller sites elsewhere in the Mediterranean. This latter form also breeds in North Africa; definitely in Tunisia, probably in Algeria and possibly in Morocco. Because of its nocturnal habits and the problems of accessing some of the small islands on which it breeds, the distribution is poorly known. A colony was discovered as recently as 2009, on Lampedusa. The storm petrel has been recorded as a vagrant in several European countries as far east as Ukraine, in the Guinea region of West Africa, and in Turkey, Israel, Lebanon, and the US. Although no North American records were reported for more than 30 years after the first in 1970, this bird has been more or less annual in small numbers since 2003. The storm petrel breeds on exposed and usually uninhabited islands, which it visits only at night. …

The storm petrel normally flies within 10 m (33 ft) of the water surface and typically feeds by picking items off the sea as it patters over the surface. Birds have been observed diving for food to a depth of not more than 0.5 m (20 in). and it is claimed, using indirect measurements, that the Mediterranean subspecies reaches depths of up to 5 m (16 ft)). A bird may range up to 200 km (120 mi) over the course of two or three days in search of food. Although the bird usually feeds during the day, in the breeding season petrels will often feed at night close to the shore. The typical prey consists of surface organisms such as small fish, squid, crustaceans and jellyfish. The storm petrel will also eat offal and oily food, often located by smell, and will follow ships. In the Atlantic, more than half the food items are zooplankton and the fish caught include small herring and sprats; whale carcasses are scavenged where available. During digestion, the plankton is quickly converted to an oily orange liquid that owes its colour to carotenoids. Larger prey items take longer to digest. The oil, rich in vitamin A, is produced by a large gland in the stomach. The Mediterranean subspecies' diet is mainly fish, particularly Mediterranean sand eels. Petrels also catch opossum shrimps from waters close to the colony. …

Its association with storms makes the storm petrel a bird of bad omen to mariners; they are said to either foretell or cause bad weather. A more prosaic explanation of their appearance in rough weather is that, like most oceanic seabirds, they rely on the winds to support them in flight and just sit on the water surface when becalmed. The birds were sometimes thought to be the souls of perished sailors, and killing a petrel was believed to bring bad luck. The petrel's reputation led to the old name of witch, although the commonest of the folk names is Mother Carey's chicken, a name also used for storm petrels in general in the UK and North America from at least 1767. This is believed to be a corruption of mater cara (dear mother, the Virgin Mary), a reference to the supernatural Mother Carey, or a superstitious modification of an earlier Mother Mary's chicken to reduce the potency of the religious name. The Mother Carey character appears a number of times in literature. In the Cicely Fox Smith poem "Mother Carey", she calls old sailors to return to the sea, but in John Masefield's poem of the same name she is seen as a wrecker of ships. …