Cormorant
Phalacrocoracidae is a family of 40 species of aquatic birds known as cormorants and shags. Several different classifications of the family have been proposed and the number of genera is disputed; the great cormorant and the common shag are the only two species of the family encountered on the British Isles, "cormorant" and "shag" appellations have been assigned to different species in the family somewhat haphazardly. Cormorants and shags are medium-to-large birds, with body weight in the range of 0.35–5 kilograms and wing span of 45–100 centimetres. The majority of species have dark feathers; the bill is long and hooked. Their feet have webbing between all four toes. All species are fish-eaters, they are excellent divers, under water they propel themselves with their feet with help from their wings. They have short wings due to their need for economical movement underwater, have the highest flight costs of any flying bird. Cormorants nest in colonies on trees, islets or cliffs, they are coastal rather than oceanic birds, some have colonised inland waters – indeed, the original ancestor of cormorants seems to have been a fresh-water bird.
They range around the world, except for the central Pacific islands. No consistent distinction shags; the names'cormorant' and'shag' were the common names of the two species of the family found in Great Britain, Phalacrocorax carbo and P. aristotelis. "Shag" refers to the bird's crest. As other species were discovered by English-speaking sailors and explorers elsewhere in the world, some were called cormorants and some shags, depending on whether they had crests or not. Sometimes the same species is called a cormorant in one part of the world and a shag in another, e.g. the great cormorant is called the black shag in New Zealand. Van Tets proposed to divide the family into two genera and attach the name "cormorant" to one and "shag" to the other, but this flies in the face of common usage and has not been adopted; the scientific genus name is Latinised Ancient Greek, from φαλακρός and κόραξ. This is thought to refer to the creamy white patch on the cheeks of adult great cormorants, or the ornamental white head plumes prominent in Mediterranean birds of this species, but is not a unifying characteristic of cormorants.
"Cormorant" is a contraction derived either directly from Latin corvus marinus, "sea raven" or through Brythonic Celtic. Cormoran is the Cornish name of the sea giant in the tale of Jack the Giant Killer. Indeed, "sea raven" or analogous terms were the usual terms for cormorants in Germanic languages until after the Middle Ages; the French explorer André Thévet commented in 1558, "... the beak similar to that of a cormorant or other corvid," which demonstrates that the erroneous belief that the birds were related to ravens lasted at least to the 16th century. Cormorants and shags are medium-to-large seabirds, they range in size from the pygmy cormorant, at as little as 45 cm and 340 g, to the flightless cormorant, at a maximum size 100 cm and 5 kg. The extinct spectacled cormorant was rather larger, at an average size of 6.3 kg. The majority, including nearly all Northern Hemisphere species, have dark plumage, but some Southern Hemisphere species are black and white, a few are quite colourful.
Many species have areas of coloured skin on the face which can be bright blue, red or yellow becoming more brightly coloured in the breeding season. The bill is long and hooked, their feet have webbing between all four toes, as in their relatives. They are coastal rather than oceanic birds, some have colonised inland waters – indeed, the original ancestor of cormorants seems to have been a fresh-water bird, judging from the habitat of the most ancient lineage, they range around the world, except for the central Pacific islands. All are fish-eaters, dining on small eels and water snakes, they dive from the surface, though many species make a characteristic half-jump as they dive to give themselves a more streamlined entry into the water. Under water they propel themselves with their feet, though some propel themselves with their wings; some cormorant species have been found, using depth gauges, to dive to depths of as much as 45 metres. After fishing, cormorants go ashore, are seen holding their wings out in the sun.
All cormorants have preen gland secretions. Some sources state that cormorants have waterproof feathers while others say that they have water permeable feathers. Still others suggest that the outer plumage absorbs water but does not permit it to penetrate the layer of air next to the skin; the wing drying action is seen in the flightless cormorant but in the Antarctic shags and red-legged cormorants. Alternate functions suggested for the spread-wing posture include that it aids thermoregulation or digestion, balances the bird, or indicates presence of fish. A detailed study of the great cormora
Impala
The impala is a medium-sized antelope found in eastern and southern Africa. The sole member of the genus Aepyceros, it was first described to European audiences by German zoologist Hinrich Lichtenstein in 1812. Two subspecies are recognised—the common impala, the larger and darker black-faced impala; the impala weighs 40 -- 76 kg. It features a reddish brown coat; the male's slender, lyre-shaped horns are 45–92 centimetres long. Active during the day, the impala may be gregarious or territorial depending upon the climate and geography. Three distinct social groups can be observed: the territorial males, bachelor herds and female herds; the impala is known for two characteristic leaps. Browsers as well as grazers, impala feed on monocots, forbs and acacia pods. An annual, three-week-long rut takes place toward the end of the wet season in May. Rutting males fight over dominance, the victorious male courts female in oestrus. Gestation lasts six to seven months, following which a single calf is born and concealed in cover.
Calves are suckled for four to six months. The impala is found sometimes on the interface between woodlands and savannahs. While the black-faced impala is confined to southwestern Angola and Kaokoland in northwestern Namibia, the common impala is widespread across its range and has been reintroduced in Gabon and southern Africa; the International Union for Conservation of Nature classifies the impala as a species of least concern. The first attested English name, in 1802, was palla or pallah, from the Tswana phala'red antelope', its Afrikaans name, rooibok'red buck', is sometimes used in English. The scientific generic name Aepyceros comes from Ancient Greek αἰπύς + κέρας; the impala belongs to the family Bovidae. It was first described by German zoologist Martin Hinrich Carl Lichtenstein in 1812. In 1984, palaeontologist Elisabeth Vrba opined that the impala is a sister taxon to the alcelaphines, given its resemblance to the hartebeest. A 1999 phylogenetic study by Alexandre Hassanin and colleagues, based on mitochondrial and nuclear analyses, showed that the impala forms a clade with the suni.
This clade is sister to another formed by the klipspringer. An rRNA and β-spectrin nuclear sequence analysis in 2003 supported an association between Aepyceros and Nesotragus; the following cladogram is based on the 1999 study: Up to six subspecies have been described, although only two are recognised on the basis of mitochondrial data. Though morphologically similar, the subspecies show a significant genetic distance between them, no hybrids between them have been reported. A. m. melampus Lichtenstein, 1812: Known as the common impala, it occurs across eastern and southern Africa. The range extends from central Kenya westward into southeastern Angola. A. m. petersi Bocage, 1879: Known as the black-faced impala, it is restricted to southwestern Africa, occurring in northwestern Namibia and southwestern Angola. According to Vrba, the impala developed from an alcelaphine ancestor, she noted that while this ancestor has diverged at least 18 times into various morphologically different forms, the impala has continued in its basic form for at least five million years.
Several fossil species have been discovered, including A. datoadeni from the Pliocene of Ethiopia. The oldest fossil discovered suggests its ancient ancestors were smaller than the modern form, but otherwise similar in all aspects to the latter; this implies. Its gregarious nature, variety in diet, positive population trend, defence against ticks and symbiotic relationship with the tick-feeding oxpeckers could have played a role in preventing major changes in morphology and behaviour; the impala is a slender antelope similar to the kob or Grant's gazelle in build. The head-and-body length is around 130 centimetres. Males reach 75–92 centimetres at the shoulder, while females are 70–85 centimetres tall. Males weigh 53–76 kilograms and females 40–53 kilograms. Sexually dimorphic, females are hornless and smaller than males. Males grow lyre-shaped horns 45 -- 92 centimetres long; the horns ridged and divergent, are circular in section and hollow at the base. Their arch-like structure allows interlocking of horns, which helps a male throw off his opponent during fights.
The glossy coat of the impala shows two-tone colouration – the reddish brown back and the tan flanks. Facial features include white rings around a light chin and snout; the ears, 17 centimetres long, are tipped with black. Black streaks run from the buttocks to the upper hindlegs; the bushy white tail, 30 centimetres long, features a solid
Crocodile
Crocodiles or true crocodiles are large semiaquatic reptiles that live throughout the tropics in Africa, the Americas and Australia. Crocodylinae, all of whose members are considered true crocodiles, is classified as a biological subfamily. A broader sense of the term crocodile, Crocodylidae that includes Tomistoma, is not used in this article; the term crocodile here applies to only the species within the subfamily of Crocodylinae. The term is sometimes used more loosely to include all extant members of the order Crocodilia, which includes the alligators and caimans, the gharial and false gharial, all other living and fossil Crocodylomorpha. Although they appear similar, crocodiles and the gharial belong to separate biological families; the gharial, with its narrow snout, is easier to distinguish, while morphological differences are more difficult to spot in crocodiles and alligators. The most obvious external differences are visible in the head, with crocodiles having narrower and longer heads, with a more V-shaped than a U-shaped snout compared to alligators and caimans.
Another obvious trait is that the upper and lower jaws of the crocodiles are the same width, the teeth in the lower jaw fall along the edge or outside the upper jaw when the mouth is closed. When the crocodile's mouth is closed, the large fourth tooth in the lower jaw fits into a constriction in the upper jaw. For hard-to-distinguish specimens, the protruding tooth is the most reliable feature to define the species' family. Crocodiles have more webbing on the toes of the hind feet and can better tolerate saltwater due to specialized salt glands for filtering out salt, which are present, but non-functioning, in alligators. Another trait that separates crocodiles from other crocodilians is their much higher levels of aggression. Crocodile size, morphology and ecology differ somewhat among species. However, they have many similarities in these areas as well. All crocodiles are semiaquatic and tend to congregate in freshwater habitats such as rivers, lakes and sometimes in brackish water and saltwater.
They are carnivorous animals, feeding on vertebrates such as fish, reptiles and mammals, sometimes on invertebrates such as molluscs and crustaceans, depending on species and age. All crocodiles are tropical species that, unlike alligators, are sensitive to cold, they separated from other crocodilians during the Eocene epoch, about 55 million years ago. Many species are at the risk of some being classified as critically endangered; the word "crocodile" comes from the Ancient Greek κροκόδιλος, "lizard", used in the phrase ho krokódilos tou potamoú, "the lizard of the river". There are several variant Greek forms of the word attested, including the form κροκόδειλος found cited in many English reference works. In the Koine Greek of Roman times and crocodeilos would have been pronounced identically, either or both may be the source of the Latinized form crocodīlus used by the ancient Romans. Crocodilos or crocodeilos is a compound of krokè, drilos/dreilos, although drilos is only attested as a colloquial term for "penis".
It is ascribed to Herodotus, describes the basking habits of the Egyptian crocodile. The form crocodrillus is attested in Medieval Latin, it is not clear whether this derives from alternative Greco-Latin forms. A corrupted form cocodrille was borrowed into Middle English as cocodril; the Modern English form crocodile was adapted directly from the Classical Latin crocodīlus in the 16th century, replacing the earlier form. The use of -y- in the scientific name Crocodylus is a corruption introduced by Laurenti. A total of 15 extant species have been recognized. Further genetic study is needed for the confirmation of proposed species under the genus Osteolaemus, monotypic. A crocodile's physical traits allow it to be a successful predator, its external morphology is a sign of its predatory lifestyle. Its streamlined body enables it to swim swiftly. Crocodiles have webbed feet which, though not used to propel them through the water, allow them to make fast turns and sudden moves in the water or initiate swimming.
Webbed feet are an advantage in shallow water. Crocodiles have a palatal flap, a rigid tissue at the back of the mouth that blocks the entry of water; the palate has a special path from the nostril to the glottis. The nostrils are closed during submergence. Like other archosaurs, crocodilians are diapsid; the walls of the braincase lack supratemporal and postfrontal bones. Their tongues are not held in place by a membrane that limits movement. Crocodiles have smooth skin on their bellies and sides, while their dorsal surfaces are armoured with large osteoderms; the armoured skin is thick and rugged, providing some protection. They are still able to absorb heat through this armour, as a network of small capillaries allows blood through the scales to absorb heat. Crocodilian scales have pores believed to be sensory in function, analogous to the lateral line in fishes, they are seen on their upper an
Saddle-billed stork
The saddle-billed stork is a large wading bird in the stork family, Ciconiidae. It is a widespread species, a resident breeder in sub-Saharan Africa from Sudan and Kenya south to South Africa, in The Gambia, Senegal, Côte d'Ivoire and Chad in west Africa; this is a close relative of the widespread Asian and Australian black-necked stork, the only other member of the genus Ephippiorhynchus. This is a huge bird that attains a height of 150 cm, a length of 142 cm and a 2.4–2.7 m wingspan. The male is larger and heavier than the female, with a range of 5.1–7.52 kg, with a mean mass of 6.38 kg. The female is between 5 and 6.84 kg, with a mean mass of 5.95 kg. It is the tallest of the storks, due in no small part to it long legs; the long bill measures from 27.3 to 36 cm. The sexes can be distinguished by the golden yellow irises of the female and the brown irises and dangling yellow wattles of the male, it is spectacularly plumaged. The head, back and tail are iridescent black, with the rest of the body and the primary flight feathers being white.
Juveniles are browner grey in plumage. The massive bill is red with a yellow frontal shield; the legs and feet are black with pink hocks. On the chest is a bare red patch of skin, whose colour darkens during breeding season, they are silent except for bill-clattering at the nest. Like most storks, these fly with the neck outstretched, not retracted like a heron. To experienced birdwatchers on the other hand, this makes them recognizable if seen from a distance, it has been suggested that due to the large size and unusual appearance in flight, this species is the basis for the "big bird" and kongamato cryptids. The saddle-billed stork breeds in other floodlands in tropical lowland, it builds a large, deep stick nest in a tree, laying one or two white eggs weighing about 146 g each. It does not form breeding colonies, is found alone or in pairs; the incubation period is 30–35 days, with another 70 – 100 days before the chicks fledge. The saddle-billed stork, like most of its relatives, feeds on fish and crabs, but on small birds and reptiles.
They move in a similar way to the larger herons. This bird is represented in an Ancient Egyptian hieroglyph that had the phonetic value "bꜣ": Its description is erroneously given as "jabiru", this species' Latin American relative; the Third Dynasty pharaoh Khaba incorporated this hieroglyph in his name. Saddle-billed Stork - The Atlas of Southern African Birds Afrika online: Okawango – Sattelstorch – Ephippiorhynchus senegalensis – Saddlebilled stork photo
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Video: Zambia's Bangweulu Wetlands, National Geographic Society