Marmelalk
| Marmelalk | ||||||||||
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Marmelalk ( Brachyramphus marmoratus ) in a typical resting position on the water |
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| Scientific name | ||||||||||
| Brachyramphus marmoratus | ||||||||||
| ( Gmelin , 1789) |
The Marmelalk ( Brachyramphus marmoratus ) is a small species from the cauliflower family and is native to the northern Pacific . It breeds in forests far inland and not close to the coast, which is very unusual for a member of this family. It prefers to breed on coastal redwoods . It was not until 1974 that a tree climber discovered a chick and made the nesting behavior of this species known.
description
The Marmelalk reaches a body length of 25 centimeters. It weighs between 188 and 253 grams. The beak is dark, slender and very pointed. The wings are slender and pointed. The iris is dark brown, the beak, legs and feet are black.
In the splendid dress , the entire body plumage is irregularly spotted dark chocolate brown on a white background. The feathers on the front back are lined with a thin reddish color. The wing feathers and the tail are black-brown. The body color varies greatly from person to person, some individuals can be almost a monochrome dark brown, others are paler and show extensive white plumage.
In the simple dress the reddish to brown tones are missing, the plumage is exclusively black and white, so that the bird is reminiscent of a guillemot . The top of the head is black, with the black surface extending over the eyes. The neck, the back and the trunk as well as the upper wing-coverts are also black-gray. Some birds, especially not yet sexually mature birds between the ages of one and two, also show this simple dress in summer. Other non-sexually mature birds show a mixed form between splendid and simple dress.
Marmalks resting on the sea swim with their heads upright and their tail almost vertically upright. Attentive jellyfish stretch their necks far forward, giving them a long, thin-necked profile that is not found in other small species of alkenbird outside the genus Brachyramphus . The legs and feet are poorly developed and sit very far back on the body, so that the Marmelalk cannot move very well on land and cannot assume a fully upright posture, as found in other alken birds.
distribution
The North American jellyfish breed on the west coast of North America from southern California via Oregon , Washington , British Columbia and the west coast from Vancouver Island to southeast Alaska and the western Aleutian Islands . However, the prerequisite is always an extensive population of old trees, which is why the Marmelalk deposits in California, Oregon and Washington are small and fragmented, because these conditions are often no longer met.
Marmalalk are found in a region where the surface temperature of the seawater is between 5 and 17 ° C in summer and between 4 and 15 ° C in winter. The species usually lives near the coast and is the most common alken bird in sheltered sea bays on the coast of British Columbia, southeastern Alaska, the Prince William Sound and Kodiak Island . The species likes to use regions with numerous small islands and penetrates deep into bays, fjords and river mouths, even if the salinity of the water there is low. In some regions, the species even makes targeted use of brackish water zones and freshwater lagoons and even seeks out large inland lakes. The Marmelalk is the only alken bird that does this regularly.
Marmelalken are very good fliers and occasionally reach Ontario , Québec , Newfoundland and Florida as random visitors .
food
Marmelalks look for their food mainly in shallow coastal waters and prefer sheltered bays and fjords. Far from the coast they are rarely seen. They eat small fish that are found in schools, as well as invertebrates. While ingesting they occasionally group together to form flocks that include other alkenbirds, gulls, and cormorants. This happens especially when sand eels and schools of herring are near the coast.
Reproduction
The marmelalk shows two peculiarities in its reproductive behavior: It usually breeds on trees, which is not found in the family of the alkenbird except for the Kamchatka marmelalk . Together with the other two species of the genus Brachyramphus, it is also one of the alken birds that generally do not breed in colonies. But it also shows social interactions with other conspecifics in its breeding area. This includes repeated flying over the treetops by individuals, pairs and small groups of birds. They fly at treetop height in the immediate vicinity of the nesting sites.
The breeding area is inland and is usually an average of 16.8 kilometers from the coast. Extreme nest locations can be found up to 40 kilometers inland. Typical nest locations are old trees that are at least 200 years old. Typical of the forests in which jellyfish nest is a small undergrowth, but a pronounced growth of moss and epiphytes on the trees. The top of the trees is on average around 64 meters high, the size of the forests in which jellyfish breed is on average 206 hectares. The nest is located in the upper area of the nesting tree about one meter away from the tree trunk on a strong tree branch that offers a nesting platform about twenty by thirty centimeters. The nest is padded with lichen and moss and mostly not visible from above due to the branches hanging over it. Therefore, breeding jellyfish cannot be seen from the ground or from the air. Ground-breeding jellyfish have also been observed in Alaska.
In California, eggs are laid from mid-March to mid-July. The breeding season begins almost a month later for the US states. In Alaska, eggs are laid between mid-May and early July. Females lay just one egg, as is typical for many species of the cauliflower family. Both parent birds breed and each have two lateral breeding spots . The nestlings hatch after an incubation period of 27 to 30 days. Immediately after hatching, the nestling is fledged continuously for two days . The parent birds feed the nestling small fish, which they usually carry individually across their beak. The nestling period is 27 to 30 days, then the young bird usually flies alone to the sea. It is not yet known how the young birds find this route. Some juveniles can see the sea shortly after taking off, but others have to travel long distances before the coast can be seen. Young birds may remember the flight direction of the parent birds and use it as a guide.
The breeding success of the jellyfish has not yet been investigated in detail, as only a few nests have been observed from the start of laying until the young birds hatch. However, it seems to be very low overall. Eggs and young birds are regularly eaten by ravens and crows, predatory mammals and squirrels. Out of 32 nests observed, only nine young birds flew out.
Duration
Exact inventory figures for the Marmelalk are not available. The total population was estimated to be at least 200,000 individuals in Alaska, 50,000 in British Columbia, 5,500 in Washington, 5,000 to 15,000 in Oregon, and 6,450 in California by the end of the 20th century.
Danger
The main threats to the Marmelalk are the deforestation of the ancient forests in which this species breeds. Many animals have also fallen victim to being caught in fishing nets and pollution from oil production systems. The Marmelalk has been classified as endangered since 1992. The bird has become an important symbol for the protection campaign to preserve the ancient forests on the American Pacific coast. In some parks on Vancouver Island , in Nimpkish Lake Provincial Park or on Flores Island , in Flores Island Marine Provincial Park , it is under strict protection.
Systematics
The Kamchatka marmelalk has long been considered a subspecies of the marmelalk. In 1998 it was possible to prove on the basis of genetic studies that this species is less closely related to the Marmelalk than the short-billed lalk .
supporting documents
literature
- Anthony J. Gaston, Ian L. Jones: The Auks (= Bird Families of the World. Vol. 4 (recte 5)). Oxford University Press, Oxford u. a. 1998, ISBN 0-19-854032-9 .
Single receipts
- ^ Gaston, p. 192
- ↑ Gaston et al., P. 194
- ↑ Gaston et al., P. 195
- ↑ Gaston et al., P. 197
- ↑ Gaston et al., P. 198
- ↑ Gaston et al., P. 198
- ↑ Gaston et al., P. 199
- ↑ Gaston et al., P: 199
- ↑ Gaston et al., P. 194
- ^ VL Friesen, JF Piatt, AJ Baker: Evidence from cytochrome b sequences and allozymes for a "new" species of alcid: the Long-billed Murrelet (Brichyramphus Perdix). In: Condor. Vol. 98, 1996, ISSN 0010-5422 , pp. 681-690, online (PDF; 839 kB) .
Web links
- Brachyramphus marmoratus in the endangered Red List species the IUCN 2008. Posted by: BirdLife International, 2008. Accessed January 31 of 2009.
- Videos, photos and sound recordings of Brachyramphus marmoratus in the Internet Bird Collection