Shearwater is a generic name for 6 genera and 37 species. Shearwaters form flocks of hundreds of individuals during feeding and migration. They form breeding colonies that can number in the hundreds of thousands. The world population of shearwaters is in the millions.
The Cory’s Shearwater Calonectris diomedea is its scientific name, one of the largest species of birds that exist in Spain. The head and back are of a yellowish-gray hue, but intensify in dark brown on the back, rump and back of the wings. The eyes have a white ring that can only be seen up close.
It is a pelagic species that lives in the open sea, but is sometimes found in wide coves or near the coasts, in layers and islands. Pines in colonies occupying steep rocky areas of islands and prominent areas. Among the most striking features of this particular bird, The cheeks and sides of the head are gray spotted white as are the flanks.
It is present in the Atlantic and the Pacific, as well as in the Mediterranean, mainly in the summer. It is abundant in southern Europe and northeastern Africa. Outside, the breeding season can be found in Western Ireland, northern France and southwestern England, as well as in the Strait of Gibraltar, where part of the population passes through on its relocations.
The belly, throat and underside of the wings are white. The tail is dark brown like the wings. The beak is yellow with highly developed nasal tubes. In this species the difference between female and male can be distinguished relatively well, provided it has a thinner bill.
Although its design can be confused with other shearwaters, the larger size is a sure distinction. The trailing edge of the wings is also visible, very dark, almost black, and is a good feature for identification. This type of shearwaters breeds on the Spanish Mediterranean coast, Columbretes and Balearic Islands, and also on the Berlangas Islands off the Atlantic coast of Portugal, where, by the way, the colonies have been plundered by fishermen.
As for the breeding area of this bird, there is evidence of breeding in certain areas of the islands off the Galician Atlantic coast, although there is a lack of data to guarantee it emphatically. The Cory’s Shearwater reaches a high density in the proximity of its breeding areas. In addition to the colonies established on the coasts of the Iberian Peninsula, it is also a breeder in the Canary Islands.
They are present in our archipelago from the end of February to the beginning of November, during which the reproductive cycle of the species lasts. Breeding areas can be found in all the Canary Islands and islets, both on the coast and inland, but often in inaccessible places. (see article: Parakeet).
There, as in the Berlangas, lives the subspecies borealis, which is slightly larger than the Mediterranean species diomedea. On arrival at the nesting sites it occurs in March, although it is difficult to determine the dates, because this shearwater is present in abundance and sides from 300 to 400 copies, most often near the rocky ridges where nests.
These particular birds usually build their nests inside holes and rock caves, where several hens belonging simultaneously to several partners were found. Despite being suddenly present in breeding colonies, they do not lay a single egg until the last days of May and perhaps in many cases until the first week of June. In this month all adults are already incubating.
The young are highly developed in July and that is when formerly and still today (Canary Islands) was at its peak performance of professional “apardeleros” in the collection of chicks that obtained abundant fat with these birds. The nest of this crappie is usually built with sticks and algae. Incubation, which involved both sexes, lasts about four weeks, leaving the nest of the young in October and even later.
Feed mainly on very small mollusks, fish eggs and plant material. Rubbing with the surface of the water beak and occasionally small diving drops from height, not more than 4 or 5 meters, but by laying completely in water. Often observed sleeping in large groups at sea.
Cagarro is dispersed after leaving the Mediterranean breeding colonies along the coast and up to the Iberian Peninsula towards Biscay Bay, one of its favorite feeding grounds. Atlantic island-breeding birds range along the coast from West Africa to South Africa.
The Berlengas Islands (Portugal), Cory’s shearwaters remain at sea in front of their caves or holes for up to two hours after sunset. Here, as in the Mediterranean nest in small groups and large caves. Some were seen by the English ornithologist Lockley incubating the egg sitting on platforms formed by small stones.
Observations made at Estaca de Bares (La Coruña) in the autumn months (Huyskens 1971), it follows that it is one of the few species that show a double movement both east and west, although, like other species, it seems that this direction is predominant.
It is very likely that within the Bay of Biscay there is a circular movement since it was also observed in numerous camps off the southwestern tip of Ireland (Cape Clear Island). Observations from the Stake of Bars in October 1969 revealed large numbers of gray shearwaters. This species was barely encircled, so there was no recovery to elucidate its movements.
The Balearic Shearwater is a bird that is endemic to the Balearic Islands, and is known to be the only place for this species to fulfill its reproductive phase. There are colonies all over the archipelago, the most important ones in Formentera.
After breeding, it can be observed on the west coast of France, even when reaching the British Isles and the south of the Scandinavian peninsula. Part of the population may live in the northwest of the African continent. Outside the reproductive period, it is a strict marine species, although it remains in the water near the coast.
This species of Balearic Shearwater is more rounded than the other shearwaters. It is about 35 cm long and has a wing tip of about 80 cm and weighs about 500 grams. It has a small head and an elongated grayish bead. The legs extend to the back of a relatively short tail.
The plumage of Balearic shearwaters is of a dark variable. The upperparts are chocolate, while ventral and underwings are light gray or even cream. The throat, axillary area and the final part of the belly are brown. There is variability of shades among different individuals. There are no differences between sexes or ages.
The diet of this Balearic shearwater feeds on live-caught fish, such as fish and octopus, although it may consume current from fishing boats, especially during the breeding season. It is sometimes associated with whales and tuna because these can bring schools of fish to the surface.
This species arrives at the breeding colonies in February and carries out the design before the end of the month. Remains on coastal cliffs, inside caves or galleries that can rent one or more pairs. The position is a single white egg, which will incubate for two months. In mid-May the hatch is touched and the hen participates in both parents until they leave the farm 65 days.
After the breeding period, at the end of June, the population disperses in the western Mediterranean and crosses the Strait of Gibraltar to the Bay of Biscay. Some individuals may go as far north as the British Isles. In those areas, they will spend the summer and autumn and change their plumage. It is also true that a small part of the population does not leave the Mediterranean during these months. (see article: Blue-headed Parrot).
When the melting period is over, the water cutter returns to the Mediterranean to spend the winter. It doesn’t seem to have much credibility in the winter scene, which is more important when it comes to food that will be placed in the colder months.
The most recent estimates (2005 data) place the population at about 2,400 breeding pairs, distributed in different colonies located in the Balearic Islands. However, very important groups (more than 8,000 individuals) were counted outside the breeding period. This fact suggests the existence of a high percentage of non-breeding individuals, both juveniles and adults that in certain years do not breed.
The Balearic cagoule is a long-lived species, with a very low reproduction rate and also has a very small and localized population. All this makes it a very vulnerable species to the threats that are closing in on it.
The most important threats are currently predation by rats and cats, the interaction of longline fishing and overexploitation of prey species, and the loss or degradation of breeding habitat due to coastal urbanization.
Among the measures for the conservation of the species, the breeding colonies were declared protected areas, rat extermination activities, cat control, colony surveillance, etc. were carried out, and knowledge about the biology of the species has been improved.
Lesser Black-backed Shearwater
Puffinus griseus is its scientific name. It is an abundant species so to speak, the total population recently estimated to be about 20 million, although the number of copies has been reduced in many areas. It disappears from some nesting islands due to habitat degradation.
In southern New Zealand, every year, Maori search some juveniles for food and oil, but this controlled activity has little or no impact on the total population. In recent years, off the west coast of North America, the number of crappies declined significantly; this may be related to a general increase in water temperatures in that area.
Open ocean. Although it occupies a large area of ocean, it is concentrated around springs and on the continental shelf, where the water is cooler, as well as at the meeting point of warm and cold water masses. You can approach the coast if the water is deep. It occurs on islands in the southern oceans, if the ground is suitable for touching or if there are rock crevices suitable for nesting.
In calm water, the shearwater shadow flies under the ocean, with rapid, stiff movements of his narrow wings; In windy conditions, glide over the waves effortlessly. He is sociable at sea.It can often be observed in concentrations of hundreds or even thousands of individuals flying in long, straight formations or resting in groups of numerous specimens in the water.
Although it is generally the most abundant seabird along the California coast, the dull-billed tropicbird builds its nest only in the southern part of the Southern Hemisphere, around Australia, New Zealand, and southern South America.
In search of food, it dives a few inches underwater and swims underwater and flaps its wings. It also emerges from the surface and catches food that floats or lies below while in the water. It sometimes feeds on whales, dolphins and other seabirds.
Usually fish, crustaceans. Diet in the North Pacific consists mainly of fish, but also shrimp and other crustaceans, octopus and jellyfish. In the North Atlantic, usually feeds on shrimp and euphausiid fish.
What has happened in Tenerife with respect to these birds
The shearwater is a pelagic seabird of the family Procellariidae only approaching the cliffs to nest in burrows called Hura where the sounds are reminiscent of a child’s cry, so there will be names like anima, perhaps because it also builds the nest at night and it is the night when the chicks released to fly to the moon shining over the ocean. One chick per life where they lay a single egg. (see article: Barranquero Parrot).
According to the report, which describes one million sites to protect marine areas in international waters, adult Canary shearwaters will travel more than 800 kilometers per day in search of food. In Mediterranean colonies, these seabirds often travel no more than 300 kilometers from the colony of their peers.
A study on the spatial ecology and conservation of seabirds prepared by the Spanish Ornithological Society (SEO