THE WILSON'S STORM PETREL

 

Wilson's storm petrel (Oceanites oceanicus), also known as Wilson's petrel, is a small seabird of the austral storm petrel family Oceanitidae. It is one of the most abundant bird species in the world and has a circumpolar distribution mainly in the seas of the southern hemisphere but extending northwards during the summer of the northern hemisphere. The world population was estimated in 2022 as stable at 8 to 20 million birds.^[2] In 2010 it had been estimated at 12–30 million.^[3] A 1998 book had estimated more than 50 million pairs.^[4] The name commemorates the Scottish-American ornithologist Alexander Wilson. The genus name Oceanites refers to the mythical Oceanids, the three thousand daughters of Tethys. The species name is from Latin oceanus, "ocean".^[5]

 

Originally described in the genus Procellaria it has been placed under the genus Oceanites. Two or three subspecies are recognized and one population maorianus from New Zealand may be extinct. The nominate population breeds from Cape Horn to the Kerguelen Islands 

 

 

while exasperatus breeds along the Antarctic coast in the South Shetland and other islands. The population from Tierra del Fuego was described as chilensis (=wollastoni, magellanicus) but this is considered a nomen nudum although some authors have reinstated it, noting that it can be distinguished by white mottling on the belly.^[6][7]

 

 

 

The name Mother Carey's chicken was used in early literature and often applied to several petrel species while the generic name of stormy petrel referred to the idea that their appearance foretold stormy weather. F. M. Littler and others called it the yellow-webbed storm-petrel.^[8]

Wilson's Storm Petrel with distinctive yellow webbing between its toes

Wilson's storm petrel is a small bird, 16–18.5 cm (6.3–7.3 in) in length with a 38–42 cm (15–16.5 in) wingspan. It is slightly larger than the European storm petrel and is essentially dark brown in all plumages, except for the white rump and flanks. The feet extend just beyond the square ended tail in flight. The European storm petrel has a very distinct whitish lining to the underwing and a nearly all dark upperwing. Wilson's storm petrel has a diffuse pale band along the upper wing coverts and lacks the distinctive white underwing lining.^[9] The webbing between the toes is yellow with black spots in pre-breeding age individuals.^[10][11]

This species breeds on the Antarctic coastlines and nearby islands such as the South Shetland Islands during the summer of the southern hemisphere. It spends the rest of the year at sea, and moves into the northern oceans in the southern hemisphere's winter. It is much more common in the north Atlantic than the Pacific. Wilson's storm petrel is common off eastern North America in the northern summer and the seasonal abundance of this bird in suitable European waters has been revealed through pelagic boat trips, most notably in the area of the Isles of Scilly and Great Britain.

It is strictly pelagic outside the breeding season, and this, together with its remote breeding sites, makes Wilson's petrel a difficult bird to see from land. Only in severe storms might this species be pushed into headlands.

Wilson's storm petrel has a more direct gliding flight than other small petrels, and like most others it flies low over the seas surface and has the habit of pattering on the water surface as it picks planktonic food items from the ocean surface. Their unique fluttering and hovering flight is achieved often with their wings held high. Even in calm weather, they can make use of the slight breeze produced by the waves and in effect soar while using their feet to stabilize themselves.^[12] Like the European storm petrel, it is highly gregarious, and will also follow ships and fishing boats. A soft peeping noise is often heard while the birds are feeding. They feed predominantly on planktonic invertebrates close to the surface, rarely plunging below the surface to capture prey. They may however sometimes take 3–8 cm long fish in the family Myctophidae.^[13]

 

 

At 40 g on average, it is the smallest warm-blooded animal that breeds in the Antarctic region.^[14] It nests in colonies close to the sea in rock crevices or small burrows in soft earth and lays a single white egg. Like most petrels, its walking ability is limited to a short shuffle to the burrow. In the Antarctic, nests may sometimes get snowed over leading to destruction of the nest or chicks. This storm petrel is strictly 

 

 

nocturnal at the breeding sites to avoid predation by larger gulls and skuas, and will even avoid coming to land on clear moonlit nights. Both parents tend the nest and feed the single chick.^[15] The chicks call and beg for food, more vigorously when hungry.^[16] Chicks remain at nest for about 60 days and are fed on krill, fish and amphipods.^[17] Adults have the ability to identify their nest burrows^[18] in the dark and their mates by olfactory cues.^[19]

 

Population estimates in Antarctica evaluate the species to have about between 10⁵ and 10⁶ pairs.^[20] Widespread throughout its large range, Wilson's storm petrel is evaluated as least concern on the IUCN Red List of Threatened Species.^[1]

 

 

 

 

 

 

 Distribution range (blue)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

THE LONG- BEAKED COMMON DOLPHIN

 

The long-beaked common dolphin (Delphinus capensis) is a species of common dolphin. It has a more restricted range than the short-beaked common dolphin (D. delphis). It has a disjointed range in coastal areas in tropical and warmer temperate oceans. The range includes parts of western and southern Africa, much of western South America, central California to central Mexico, coastal Peru, areas around Japan, Korea and Taiwan, and possibly near Oman.^[1][3] Vagrants have been recorded as far north as Vancouver Island. They live in shallow, warmer temperature waters near the coast. They also live in the tropical and subtropical regions.^[4]

 

 

The long-beaked common dolphin is medium-sized, but smaller than the more popular bottlenose dolphin. Adults range between 1.9 and 2.5 m (6.2 and 8.2 ft), long, and can weigh between 80 and 235 kg (176 and 518 lb), although a range between 80 and 150 kg (180 and 330 lb) is more common.^[5] Males are generally longer and heavier.^[5] The color pattern on the body is unusual. The back is dark and the belly is white, while on each side is an hourglass pattern colored light grey, yellow or gold in front and dirty grey in back.^[6] This species also has a rounded melon on tops of their heads used for echolocation.^[4] It has a long, thin rostrum with up to 60 small, sharp, interlocking teeth on each side of each jaw.^[7] They have more teeth than any other delphinids.^[8]

 

The long-beaked common dolphin is medium-sized, but smaller than the more popular bottlenose dolphin. Adults range between 1.9 and 2.5 m (6.2 and 8.2 ft), long, and can weigh between 80 and 235 kg (176 and 518 lb), although a range between 80 and 150 kg (180 and 330 lb) is more common.^[5] Males are generally longer and heavier.^[5] The color pattern on the body is unusual. The back is dark and the belly is white, while on each side is an hourglass pattern colored light grey, yellow or gold in front and dirty grey in back.^[6] This species also has a rounded melon on tops of their heads used for echolocation.^[4] It has a long, thin rostrum with up to 60 small, sharp, interlocking teeth on each side of each jaw.^[7] They have more teeth than any other delphinids.^[8]

 

The long-beaked common dolphin is a member of the common dolphin genus, Delphinus within the dolphin family, Delphinidae in the cetaceans order.^[4] Until the mid-1990s, the different forms within Delphinus were not recognized as separate species, but were all considered members of the species D. delphis.^[3][5] In 1994, Heyning and Perrin^[9] did research on these species and then Kingston and Rosel^[10] confirmed there were two separate species. Currently, the two recognized species of Delphinus  are the short-beaked common dolphin (D. delphis) and the long-beaked common dolphin.^[1] The long-beaked common dolphin is generally larger with a longer beak than the short-beaked common dolphin and has a longer rostrum.

The Indo-Pacific common dolphin is sometimes considered a separate species (D. tropicalis), but is more often considered a form of the long-beaked common dolphin.^[1][3]

 

 

The long-beaked common dolphin has a varied diet consisting of small schooling fish, such as sardines, anchovies, mackerels, pilchards, mullet, drum or croaker. These dolphins may occasionally eat small cephalopods such as octopuses and squid, and more rarely eat small crustaceans like large shrimp or small crab. Since they gather in huge superpods and there is seldom enough food in one place to support all of them, smaller groups leave the main pod for a few hours to feed.^[11] They are able to dive in the water to about 900 feet (270 m) and hold their breath for up to 8 minutes to catch prey.^[4]

 

 

 

See also: Dolphin (Reproduction and sexuality)

The long-beaked common dolphin has a gestation period of 10 to 11 months typically during spring or autumn.^[4][5] The newborn calf has a length of between 80 and 100 cm (2.6 and 3.3 ft) and a weight of about 10 kilograms (22 lb).^[5] The young and juvenile dolphins coloration and patterns are darker than the adults.^[11] Typical interbirth interval ranges from one to three years.^[5] In captivity, this dolphin has hybridized with the common bottlenose dolphin (Tursiops truncatus).^[3][12] One of the hybrids has been bred back to a bottlenose dolphin, demonstrating such hybrids are fertile.^[12] The long-beaked common dolphin can live up to 40 years.^[4]

 

 

Long-beaked common dolphins are not common in human care as they are extremely difficult to keep in captivity. In the wild, however, they have been seen travelling with bottlenose dolphins, pilot whales, and yellowfin tuna.^[13]

 

 

Delphinus capensis is covered by the Memorandum of Understanding Concerning the Conservation of the Manatee and Small Cetaceans of Western Africa and Macaronesia^[14] and the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region (Pacific Cetaceans MoU).^[15] One of the main threats to the long-beaked common dolphin is fisheries. Out of 930 dolphins observed off of Peru between 1985 and 2000, 120 of them had many lacerations on their head, skin, appendages, and teeth. Most of these injuries were from fisheries-related connection.^[16] Another threat to this species is pollution because many of them have shown signs of organochlorine residue on their blubber.^[17] On the coast of California there are only about 25,000 to 43,000 dolphins and on the coast of South Africa there are 15,000 to 20,000.^[5]

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Physical characteristics

 

The long-beaked common dolphin is medium-sized, but smaller than the more popular bottlenose dolphin. Adults range between 1.9 and 2.5 m (6.2 and 8.2 ft), long, and can weigh between 80 and 235 kg (176 and 518 lb), although a range between 80 and 150 kg (180 and 330 lb) is more common.^[5] Males are generally longer and heavier.^[5] The color pattern on the body is unusual. The back is dark and the belly is white, while on each side is an hourglass pattern colored light grey, yellow or gold in front and dirty grey in back.^[6] This species also has a rounded melon on tops of their heads used for echolocation.^[4] It has a long, thin rostrum with up to 60 small, sharp, interlocking teeth on each side of each jaw.^[7] They have more teeth than any other delphinids.^[8]

 

Taxonomy

Delphinus c. tropicalis in the Red Sea

The long-beaked common dolphin is a member of the common dolphin genus, Delphinus within the dolphin family, Delphinidae in the cetaceans order.^[4] Until the mid-1990s, the different forms within Delphinus were not recognized as separate species, but were all considered members of the species D. delphis.^[3][5] In 1994, Heyning and Perrin^[9] did research on these species and then Kingston and Rosel^[10] confirmed there were two separate species. Currently, the two recognized species of Delphinus  are the short-beaked common dolphin (D. delphis) and the long-beaked common dolphin.^[1] The long-beaked common dolphin is generally larger with a longer beak than the short-beaked common dolphin and has a longer rostrum.

The Indo-Pacific common dolphin is sometimes considered a separate species (D. tropicalis), but is more often considered a form of the long-beaked common dolphin.^[1][3]

Behavior

Delphinus capensis with whale watching vessels off Kochi, Japan

Long-beaked common dolphins can live in aggregations of hundreds or even thousands.^[3] Within these large groups, smaller subgroups of 10 to 30, related in either sex or age, typically are found.^[4] They sometimes associate with other dolphin species, such as pilot whales.^[3] They have also been observed bow riding on baleen whales, and they also bow ride on boats.^[3] Breaching behavior and aerial acrobatics are common with this species.^[5]

 

Diet

 

The long-beaked common dolphin has a varied diet consisting of small schooling fish, such as sardines, anchovies, mackerels, pilchards, mullet, drum or croaker. These dolphins may occasionally eat small cephalopods such as octopuses and squid, and more rarely eat small crustaceans like large shrimp or small crab. Since they gather in huge superpods and there is seldom enough food in one place to support all of them, smaller groups leave the main pod for a few hours to feed.^[11] They are able to dive in the water to about 900 feet (270 m) and hold their breath for up to 8 minutes to catch prey.^[4]

 

Reproduction

 

 

See also: Dolphin (Reproduction and sexuality)

The long-beaked common dolphin has a gestation period of 10 to 11 months typically during spring or autumn.^[4][5] The newborn calf has a length of between 80 and 100 cm (2.6 and 3.3 ft) and a weight of about 10 kilograms (22 lb).^[5] The young and juvenile dolphins coloration and patterns are darker than the adults.^[11] Typical interbirth interval ranges from one to three years.^[5] In captivity, this dolphin has hybridized with the common bottlenose dolphin (Tursiops truncatus).^[3][12] One of the hybrids has been bred back to a bottlenose dolphin, demonstrating such hybrids are fertile.^[12] The long-beaked common dolphin can live up to 40 years.^[4]

 

Relationship to humans and other species

 

Long-beaked common dolphins are not common in human care as they are extremely difficult to keep in captivity. In the wild, however, they have been seen travelling with bottlenose dolphins, pilot whales, and yellowfin tuna.^[13]

 

Conservation

 

Delphinus capensis is covered by the Memorandum of Understanding Concerning the Conservation of the Manatee and Small Cetaceans of Western Africa and Macaronesia^[14] and the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region (Pacific Cetaceans MoU).^[15] One of the main threats to the long-beaked common dolphin is fisheries. Out of 930 dolphins observed off of Peru between 1985 and 2000, 120 of them had many lacerations on their head, skin, appendages, and teeth. Most of these injuries were from fisheries-related connection.^[16] Another threat to this species is pollution because many of them have shown signs of organochlorine residue on their blubber.^[17] On the coast of California there are only about 25,000 to 43,000 dolphins and on the coast of South Africa there are 15,000 to 20,000.^[5]

 

 

 

 Binomial name

 

 Delphinus capensis

Gray, 1828