Guadalupe Murrelet
Lummenalk ( Synthliboramphus hypoleucus )
The Lummenalk ( Synthliboramphus hypoleucus ) is a small species of the family of the Auks. Within this family, the Lummenalk, which occurs in the northern Pacific, one of the southernmost areas of distribution. It breeds on islands off the coast of California and Mexico. Although this species has a very small distribution area, two subspecies are described.
The IUCN classifies the Lummenalk because of its limited occurrence and inventory decline in recent years as endangered ( vulnerable ).
Appearance
The Lummenalk with 24 cm of length, one of the smallest and also a relatively slender Auk with a black and white plumage. There is no seasonal difference in plumage. The legs set far back on the body, so that it only moves very clumsy on land. The average weight of breeding birds is 171 g, females are slightly heavier than the males.
The top is completely black. Fresh vermausertes plumage has a slight bluish gloss, worn plumage looks grayish. The body underside is white. The small and pointy beak is black. The legs and toes are slightly bluish, the webbed feet are black and the iris is brown. Lummenalken fly with rapid wing beat. You can fly up from the water surface without start.
Young birds have the same adult birds, however. Indistinct transverse stripes on the flanks as well as a slightly shorter beak than adult birds
Within its range of Lummenalk with the Craverialk and in winter can be confused with the Marmelalk. However, the pure white underparts and paler wings distinguish the Lummenalk of these two species. Marmelalken also have a much shorter beak.
Distribution area
Together with the Craverialk this type has the southernmost distribution areas under all Alkenvögeln. The breeding areas are located on the California Channel Islands, on Guadalupe and other islands off the coast of Baja California. The Lummenalk adheres so on waters on whose surface temperature is more than 12 degrees Celsius. Outside the breeding season, he lives on the open sea, to the north then the distribution extends up to the region of British Columbia.
Food
In the dives in search of food Lummenalken often follow larger predatory fish, such as tuna, and start doing smaller fish. When diving birds use their wings, they advance with powerful strikes. Lummenalken are often seen in pairs and outside the breeding season and it is believed that they also hunt together.
During the breeding season the feeding grounds of Lummenalken are near their breeding areas, mostly on the continental shelves. Detailed studies before the California coast have demonstrated that Lummenalken in spring and summer are found mainly between the ages of 35 and 43 degrees north latitude. During the autumn of their range is greater. Then usually stay at more than 50 kilometers from the coastline.
Reproduction
The colonies are found on small, low rainfall islands with sparse and mostly thorny vegetation. Most colonies are less than 200 meters from the shoreline. The Brutorttreue is high. In one study used a large part of the ringed breeding birds same Niststandort three consecutive years. The individual nests are different distances apart, which is rather unusual for Auks, which often breed in dense colonies. Lummenalken also among the few Alkenvögeln, which occur Nachgelege. There are also twelve documented cases in which occurred second broods.
Lummenalken nest in small caves, rock crevices or under bushes in open colonies. They also use abandoned burrows of rabbits and Kaninchenkäuzen. Later in the year petrels occasionally use the burrows of Lummenalken for their brood. The breeding season is relatively little synchronized. In Santa Barbara Iceland, one study showed that Lummenalken put 80 percent of eggs over a period of 24-47 days. The earliest egg-laying took place on the island on 22 February, the peak of oviposition fell in the period from March 21 to April 21. The last eggs were laid in mid-June. The eggs are elliptical to oval and whitish to brown discolored reason mottled gray and brown and coarse speckled. In Santa Barbara Iceland reported 69 percent of nests on two eggs, 25 percent of the nest consisted of an egg. It also larger clutches were found, but these are believed to be one of two or more females occupied nest. The incubation of the eggs usually begins two days after the filing of the second ice. The incubation period averages 31 days. Young birds weigh hatching average 23.8 grams. They are brooded until they leave the nest and leave it on the second day after hatching.
Raised in captivity Lummenalken changed 48 hours after hatching their behavior significantly. While they remained quiet in her nest until that time, they were then very agile behavior and ran around excitedly in their Nistboxen. Under natural conditions they are conducted at this time by the parents birds on the high seas. They are then already very good swimmers and ashore able to climb over obstacles. Their further development on the high seas could not yet be documented. Raised in captivity Lummenvögel showed a very slow weight gain and a change of plumage until 17 days of age.
In Santa Barbara Iceland average of 72 juveniles per 100 nests fledged. Weißfußmäuse are responsible for about 44 percent of Eiverluste. Another 14 percent of the nests were abandoned by the adult birds. Among the predators of Lummenalken who beat adults and young birds are introduced mammals on the islands, barn owls, Western gulls and peregrine falcons. Some adult Lummenalken also die because they get caught on land in vegetation. As several adult Lummenalken were caught that had reach the age of more than 14 years, it is assumed that the mortality rate of breeding birds is relatively low.
Stock
The inventory is difficult in this type, as the nesting sites are far apart and the Lummenalk lives very hidden. The total population is estimated to be less than 10,000 birds, thus counted the Lummenalk to the most vulnerable alkene.
Marine pollution is the greatest threat to Lummenalken represents a large part of the total stock in the busy lives of tankers Los Angeles area and thus a single accident could have devastating consequences. Also entrained animals such as rats and feral cats pose a great hazard and the task of individual islands off Baja California as a breeding area and the significant decline in other islands is probably due to the latter. On Anacapa Island all imported rats using poisoned baits were successfully eliminated. Lummenalken are attracted to ship lights and often collide so with ships. In addition, ships at anchor near breeding colonies have led to significant disturbance of breeding activities.
Subspecies
Are described for this type two subspecies:
- P h scrippsi ( Xantus de Vesey, 1860) is the north occur more subspecies. It differs from the nominate form by a more white face. What is striking is the white line that runs above the eye.
- P h hypoleucus ( Green & Arnold, 1939) breeds on the islands off the west coast of Baja California.