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20.12.2015 17:01 - Encyclopedia Largest prehistoric animals Vol.1 Vertebrates part2 Birds ch.7 Woodpeckers and Storks
Автор: valentint Категория: Забавление   
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Storks and allies (Ciconiiformes)
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The largest of Ciconiiformes was Leptoptilos robustus, standing 1.8 metres (5.9 ft) tall and weighing an estimated 16 kilograms (35 lb).
The genus name Leptotilos is derived from the Greek word "lepto" meaning "thin or slender", which refers to the storks slim build and the Greek word "ptilo" meaning "down or soft feather", referring to the soft feather down covering the frame of the members of Leptotilos stork. The species name, "robustus" is derived from Latin word, "robur" meaning "hardness or strength". The species name robustus is a reference to the notably large size of the tibiotarsus and the thickness of its cortex.
L. robustus most likely had a slender body characteristic of extant members of Leptoptilos, but was much larger in body size and height, with individuals reaching up to at least 1.8 meters (about 6 feet) tall and weighing approximately 16 kilograms (36 lb).From Liang Bua, fragments of a left ulna, left carpometacarpus, left tibiotarsus, and a nearly complete left femur were discovered and described in 2010. In 2013, the tip of a maxilla, a left and right prosimal scapula, two furculae, a humeral and ulnar, a right proximal radius, two right ossi carpi radiales, a right femur, four phalanges and long bone fragments were additionally discovered and described.The bone fragments found of this species were indicative of its large size when compared to skeletal measurements from the extant species, Leptoptilos dubius.Due to having heavy bones and a heavy body it is assumed that that it rarely, if ever, flew. The thick walled tibiotarsus, constituting the thickest of all other extant and extinct Leptoptilini species, is an unusual feature for flying birds which usually selects for minimum mass. As well as heavier than normal bone structure, measured size ratios suggested that it may have had reduced forelimbs and therefore flight capabilities.The body size was similar in dimension to L. dubius, with the exception of its tibiotarsus. However, the fragmentary nature of the ulna and the carpometacarpus found do not allow an accurate estimate of wingspan length and the question as to whether or not L. robustus could fly is currently unknown.
Large extant species of stork are typically scavengers of carrion and compete with other mammalian carnivorous species. Pleistocene Liang Bua was highly endemic and there were no or very few large carnivorous mammals that L. robustus competed with for carrion. In the absence of such competition, food was more abundant. This abundance of food reduced the need to travel large distances in search of resources and would have put very little selection pressure on flight apparatuses and mechanisms.L. robustus may have been carnivorous, feeding on large rat species, komodo dragon and other fauna existing during its time.
Some speculate that these large storks may have fed upon a species of hominids, Homo floresiensis, that coexisted with them during the Late Pleistocene. Known as the "Hobbit race" of Liang Bua, these small stature hominids reached an estimated 0.91 metres (3.0 ft) in height. L. robustus would have towered over H. floresiensis, almost doubled in height. Adults and juveniles may have been prey for the giant stork.
Leptoptilos robustus was discovered in the Liang Bua limestone cave on the island of Flores, Indonesia which is located about 13 kilometers northwest of Ruteng. The bone fragments were collected from Pleistocene sediments at a recorded depth of 4.25-4.70 meters.The bones found were mostly likely the remains of one individual; all that were bones discovered within a single sector were of the same body size and no other large-bodied bird bone fragments were uncovered within that area. The fragments found were most likely from adult individuals indicated by the smooth surface of the bones, ossification, and the fusion of the astragulus and tibia.Comparing the osteological features, large size, and thick bone wall of the tibiotarsus to extinct and extant members of Leptoptilos, the fossil remains from Liang Bua were assigned as a new species robustus. L. robustus was described by Hanneke J.M. Meijer and Rokus Awe Due in April 2009.
The island of Flores, Indonesia is distinct in its isolation, separated from the Sunda continental shelf by deep water all year round. Currently, the limited number of species and the unbalanced nature of the species present is a consequence of the extremely insular nature of the island. Liang Bua supports only a few of the clades from the mainland and lacks specific groups such as mammalian carnivores. This resulted in the distinct dwarfism of mammals and the gigantism of other vertebrate species, an effect known as the island rule. L. robustus in the Pleistocene epoch would have experienced similar, if not the same, geographical conditions as the extant species residing on the island today.
Debate over the relation between the Liang Bua specimen and other stork species was compared using the size measurements of the fragments found to extant species. It can be inferred from the recorded dimensions of the bones that L. robustus was substantially taller and heavier than other species of Leptoptilos, which reach a maximum weight of 9 kg. The only other known Leptoptilos species that outweighs robustus is L. falconeri which is estimated to have reached up to 2 meters and weighed approximately 20 kg. L. robustus may have evolved in situ on Liang Bua from a flying ancestor. Unfortunately, the sparse fossil record of birds from South-East Asia makes the evolutionary history of robustus difficult to trace. Only Java has yielded other Leptoptilini fossils including L. dubius and L. titan from the Pleistocene. L. falconeri remains have been found in a wide geographical range from Central Asia, Africa, and central Europe. This wide range is evidence that L. robustus may be at least descended from that species. The morphological differences between the two however, rule out conspecificity. The dimensions of the fragments found suggests that L. robustus is most closely related to L. dubius, the two sharing a common ancestor.


Woodpeckers and allies (Piciformes)

The largest woodpecker is the possibly extinct imperial woodpecker (Campephilus imperialis) with a total length of about 22 inches (50 centimeters).
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The imperial woodpeckers typical size ranges from 56 to 60 cm, an enormous, stunning black-and-white woodpecker. The male imperial woodpecker has a red-sided crest, centered black, but otherwise mostly black, with large white wing-patch, thin white "braces" on its mantle and a huge ivory bill. They are all black except for the inner primaries, which are white-tipped, the white secondaries, and a white scapular stripe which, unlike the ivory-billed woodpecker, does not extend onto the neck. The female is similar, but her crest is all black and (unlike the female ivorybill) recurved at the top, lacking red. Much larger than any other sympatric woodpecker, it is the only woodpecker in the area with solid black underparts. Its voice is reportedly toy-trumpet-like. The bird was once widespread and, until the early 1950s, not uncommon throughout the Sierra Madre Occidental of Mexico, from western Sonora and Chihuahua southwards to Jalisco and Michoacбn. There is a chance that imperialis followed the mountain region northward into southern Arizona.
The imperial woodpecker prefers open montane forests made up of Durango, Mexican white, loblolly and Montezuma pines, as well as oak, usually between 2100 and 2700 meters above sea level. Most records are from elevations of 1,920-3,050 m, but there are records as low as 1,675 m. It feeds mainly on bark scaled from dead pine trees and feeding on the insect larvae found underneath. There are many reports of more than four individuals, and this grouping behaviour may be related to its foraging specialisation. Breeding has been recorded between February and June, and probably 1-4 eggs are laid. A mated pair requires a very large area of untouched mature forest to survive, approximately 26 km2 (10 sq mi); outside the breeding season, the birds are reported to form small groups of up to a dozen individuals and move about a wide area, apparently in response to the availability of food.The main food source, beetle larvae in snags, is probably distributed in patches and peaks within a short period of time. Consequently, feeding-sites are probably best exploited by "nomadic" groups. If operating in groups of seven or eight individuals, the minimum area of old-growth forest for a group is 98 km2.
The habitat in which the imperial woodpecker was located was predominantly in coniferous forests (terrain levels at 2,700-2,900 m. elevation). The area in which they lived was abundant with large dead trees which could be linked to their extinction. The area had been cleared and logged multiple times by 2010. Increasing effort in conservation biology is being devoted to the analysis of the extinction risk as well as the search for the rare, long unseen, species. There are a handful of more recent, unconfirmed sightings,the most recent of which closely followed the 2005 publication of the purported rediscovery of the ivory-billed woodpecker. Lammertink et al. (1996), after extensively reviewing post-1956 reports, conclude that the species did indeed survive into the 1990s in the central part of its range, but also consider a continued survival very unlikely. According to them, the population was always restricted in historic times, although the species was indeed present in maximum density before a catastrophic decline during the 1950s. The lack of good records from that time is apparently based more on lack of research than on actual rarity, but this seems to have changed radically only one decade later.
Recent field research by Tim Gallagher and Martjan Lammertink has found evidence — in the form of accounts by elderly residents in the bird"s range, who saw imperial woodpeckers decades earlier, and who discussed their recollections with the researchers — that foresters working with Mexican logging companies in the 1950s told the local people that the woodpeckers were destroying valuable timber, and encouraged the people to kill the birds. As part of this campaign, the foresters gave the local residents poison to smear on trees that the birds foraged on. Because groups of imperial woodpeckers tended to feed on a single huge, dead, old-growth pine tree for as long as two weeks, applying poison to such a tree would be an effective way to wipe out a group of up to a dozen of these huge woodpeckers — and, perhaps, even to kill off succeeding groups of the birds that might move in to the area, and be attracted to the same tree. Gallagher suspects that such a campaign of poisoning may be the key to the species" apparent catastrophic population crash in the 1950s, which has hitherto lacked a satisfactory explanation. A campaign of poisoning could well have killed whole groups of the bird in a short time. The premise of protecting valuable timber from the woodpeckers was, in fact, baseless. Imperial woodpeckers do not forage on, or excavate nest or roosting holes in live, healthy trees.
In Gallagher"s recent novel, The Grail Bird, in 2006, he discusses how difficult the search is for the imperial woodpecker due to its dangerous location. In Mexico"s Sierra Madre Occidental, there are major marijuana and poppy-growing regions that are patrolled by armed guards. The drug cartels often kill anyone who comes close to their crops.Gallagher"s inspiration to search for the imperial woodpecker, was the discovery of a 1956 film by dentist William Rhein, who made several trips to Mexico in search of the imperial woodpecker. This is the only known photographic record of the species.
The imperial woodpecker is known from about 160 museum specimens and a single amateur film from 1956 depicting one bird climbing, foraging and flying. The film has been restored and released by Cornell University.

 

The largest woodpecker confirmed to be extant is the great slaty woodpecker (Mulleripicus pulverulentus).
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It is found in the Indian subcontinent and Southeast Asia, ranging across Bangladesh, Bhutan, Brunei, Cambodia, India, Indonesia, Laos, Malaysia, Myanmar, Nepal, the Philippines, Singapore, Thailand and Vietnam. It is found in the greater Sundas but does not inhabit Bali.
This species prefers to inhabit areas of primary semi-open, moist deciduous and tropical evergreen forest though can on occasion range into adjacent secondary forests, clearings with scattered tall trees and similar almost park-like areas but do not generally visit heavily disturbed areas. Locally, the great slaty woodpecker prefers sprawling stands of dipterocarp and teak trees. Also found in mature sal forests, swamp forest and mangroves with tall, mature trees. The species usually occurs below an elevation of 600 m (2,000 ft), but also locally in montane areas of up to 1,100 m (3,600 ft), occasionally ranging up to 2,000 m (6,600 ft).
With the probable extinctions of the imperial woodpecker and the ivory-billed woodpecker, this species, at 48–58 cm (19–23 in) long and a weight of 360–563 g (0.794–1.241 lb), stands as the largest woodpecker in the world.Among standard measurements, the wing chord is 21.5 to 25 cm (8.5 to 9.8 in), the tail is 13.4 to 16.2 cm (5.3 to 6.4 in), the bill is 6 to 6.5 cm (2.4 to 2.6 in) and the tarsus is 3.6 to 4.1 cm (1.4 to 1.6 in). This unique-looking woodpecker has several obvious distinctive features: a very long, strong chisel-tipped bill, an elongated neck and a long tail. A slight crest maybe occasionally evident. This species plumage is almost entirely dark grey or blackish slate-grey overlaid with small white spots. The throat is paler grey and males have small red moustache. Normally, the nominate subspecies is the darkest, most slaty gray race. M. p. harterti has a more pale throat with a greater amount of whitish feather tips forming small spot and is slightly paler below than the nominate, sometimes appearing almiost whitish on the belly. The size and structure readily distinguishes this bird from almost any other species, including other woodpeckers. Occasionally, at first glance, the great slaty woodpecker is mistaken for a hornbill but, obviously, such a resemblance is slight at best.
For a bird of such great size, the great slaty woodpecker has a weak, quiet voice, especially compared to other large woodpeckers, which tend to have loud, booming voices. The species call is a whinnying cackle of 2 to 5, usually 4 notes, woikwoikwoikwoik, the initial being higher in pitched and the middle note being distinctly lower. Single dwot calls, variable in sound, strength and duration, are sometimes given while perched or in flight. Breeding pairs of these woodpeckers have been heard to softly mew at each other. In more antagonistic situations, sharp taw-whit or dew-it calls are uttered while the birds swing their heads back and forth.
Great slaty woodpeckers are mostly seen in groups consisting of 3 to 6 individuals, which consist of a breeding pair and their young from prior years. Groups often forage on shared feeding sites in the form of nests of social insects as ants, termites, wood-boring beetles and stingless bees. Ants seem to be generally favored in the diet, though larvae of other species may be eaten quite regularly as well. Occasionally, small fruit may supplement the diet. Females spend more time searching for feeding sources and males, which have slightly larger bills, spend more time opening the sources. Preferred feeding sources are mostly found in large branches or trunks of large, living trees. The groups will travel considerable distance to access these trees and, as such, the home ranges of the species are quite large. Occasionally, though, they will feed at lower levels in trees and even amongst saplings. Usually, feeding groups of these woodpeckers do not linger in any given area for long. Sometimes this species associates with slightly smaller white-bellied woodpeckers and considerably smaller greater flamebacks, with the foraging methods of the very different woodpeckers minimizing competition between the species. Perhaps more considerable competition for food sources generally comes in the form of hornbills and arboreal (or tree-dwelling) mammals. The great slaty woodpecker usually works a tree upwards and, though capable of swifter movements, has been described while foraging as if moving in "slow motion". It forages by gleaning, probing, pecking, prising off bark and hammering with powerful and loud blows to excavate the wood. Gleaning is the most important foraging method for the species, with the long neck and bill allowing it to reach out over a considerable distance into the crevices and cracks of trees. This species often flies high over the trees for long distances between successful foraging patches. In flight, its feather rustle noisily. The great slaty woodpecker usually engages in less dipping during than other woodpeckers and flies in a mixed flying style described as quite crow-like.
Like all woodpeckers, breeding pairs roost in separate tree holes but regularly vocalized to stay in contact. The pair bond appears to be lifelong. These woodpeckers engage in displays, largely for territorial purposes. Displays include head-swinging, where the appears to lag behind the body in swinging movements, whinnying calls and widen their wings and tail considerably. Few nests of the species have been described in detail, but at least occasionally nests are raised cooperatively by groups.Known nests, at anywhere from 9 to 45 m (30 to 148 ft) in height in the trees, were located in very large trees. When excavating the nest hole, both parents participate but reportedly the male does the majority of the work. The nest hole entrance will be around 10 cm (3.9 in) across, but much wider inside the tree. The pair will only use a nest from a prior year if competition is too overbearing for a newly constructed hole. The nesting season, in Malaysia at least, appears to be from March to August. The clutch reportedly consists of 2 to 4 eggs, which are incubated by both parents. Both parents also feed and generally brood the young. The young great slaty woodpeckers probably stay with their parents until the next breeding season.










 




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Автор: valentint
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