Misplaced Pages

#26973

27-573: The African jacana ( Actophilornis africanus ) is a wader in the family Jacanidae . It has long toes and long claws that enables it to walk on floating vegetation in shallow lakes, its preferred habitat. It is widely distributed in sub-Saharan Africa . For the origin and pronunciation of the name, see Jacanidae . The African jacanas was formally described in 1789 by the German naturalist Johann Friedrich Gmelin in his revised and expanded edition of Carl Linnaeus 's Systema Naturae . He placed it in

54-465: A paraphyletic assemblage. However, it indicated that the plains wanderer actually belonged into one of them. Following recent studies (Ericson et al., 2003; Paton et al., 2003; Thomas et al., 2004a, b; van Tuinen et al., 2004; Paton & Baker, 2006), the waders may be more accurately subdivided as follows, with Charadrii being repurposed into a monophyletic suborder of plovers, oystercatchers, and their close relatives. The waders are traditionally

81-416: A floating nest. The jacana has evolved a highly unusually polyandrous mating system, meaning that one female mates with multiple males and the male alone cares for the chicks. Such a system has evolved due to a combination of two factors: firstly, the lakes that the jacana lives on are so resource-rich that the relative energy expended by the female in producing each egg is effectively negligible. Secondly

108-562: A greatly enlarged order Ciconiiformes . However, the classification of the Charadriiformes is one of the weakest points of the Sibley-Ahlquist taxonomy, as DNA–DNA hybridization has turned out to be incapable of properly resolving the interrelationships of the group. Formerly, the waders were united in a single suborder Charadrii , but this has turned out to be a " wastebasket taxon ", uniting no fewer than four charadriiform lineages in

135-530: A group of two Charadriiform suborders which include 13 families . Species in the third Charadriiform suborder, Lari , are not universally considered as waders, though the Larine families which may variously be included are listed below as well. Shorebirds is a blanket term used to refer to multiple bird species that live in wet, coastal environments. Because most these species spend much of their time near bodies of water, many have long legs suitable for wading (hence

162-403: A result, an increase in dimorphism. Bigger males tend to have greater access (and appeal) to female mates because their larger size aids them in defeating other competitors. Likewise, if the species exhibits gender role reversal (where males take on roles traditionally done by females such as childcare and feeding), then males will select female mates based on traits that are the most appealing. In

189-443: A single female partner, males typically do not have distinctive dimorphic characteristics such as colored feathers, but they still tend to be larger in size compared to females. The suborder Charadrii displays the widest range of sexual dimorphisms seen in the order Charadriiformes. However, cases of sexual monomorphism, where there are no distinguishing physical features besides external genitalia, are also seen in this order. One of

216-400: A source of oxygen to live. Insects draw air into their bodies through spiracles , holes found along the sides of the abdomen . These spiracles are connected to tracheal tubes where oxygen can be absorbed. All aquatic insects have become adapted to their environment with the specialization of these structures The nymphs of the hemimetabolous orders mayflies, dragonflies and stoneflies, and

243-571: Is the least sandpiper , small adults of which can weigh as little as 15.5 grams (0.55 oz) and measure just over 13 centimetres (5 inches). The largest species is believed to be the Far Eastern curlew , at about 63 cm (25 in) and 860 grams (1 pound 14 ounces), although the beach thick-knee is the heaviest at about 1 kg (2 lb 3 oz). In the Sibley-Ahlquist taxonomy , waders and many other groups are subsumed into

270-462: The Jacana species, females compete with each other for access to male mates, so females are larger in size. Males choose female mates based on who presents herself as the strongest and who 'owns' the most territory. Another factor that leads to the development of dimorphisms in species is natural selection . Natural selection focuses on traits and the environment's response to the traits in question; if

297-451: The genus Parra and coined the binomial name Parra africana . Gmelin based his description on that by the English ornithologist John Latham who in 1785 had described and illustrated the species in his A General Synopsis of Birds . Gmelin and Latham gave the locality as "Africa": this was restricted to Ethiopia in 1915. The African jacana is now placed in the genus Actophilornis that

SECTION 10

#1733122061027

324-481: The Arctic species, such as the little stint , are amongst the longest distance migrants, spending the non- breeding season in the southern hemisphere . Many of the smaller species found in coastal habitats, particularly but not exclusively the calidrids , are often named as "sandpipers", but this term does not have a strict meaning, since the upland sandpiper is a grassland species. The smallest member of this group

351-438: The adults, only in juveniles they are white with a chestnut belly patch. The blue bill extends up as a coot -like head shield, and the legs and long toes are grey. African jacanas feed on insects and other invertebrates picked from the floating vegetations or the surface of the water. African jacanas breed throughout sub- Saharan Africa . It is sedentary apart from seasonal dispersion. It lays four black-marked brown eggs in

378-489: The biggest factors that leads to the development of sexual dimorphism in shorebirds is sexual selection . Males with ideal characteristics favored by females are more likely to reproduce and pass on their genetic information to their offspring better than the males who lack such characteristics. Mentioned earlier, male shorebirds are typically larger in size compared to their female counterparts. Competition between males tends to lead to sexual selection toward larger males and as

405-742: The body. In these insects, the volume of the film is small enough, and their respiration slow enough, that diffusion from the surrounding water is enough to replenish the oxygen in the pocket of air as fast as it is used. The large proportion of nitrogen in the air dissolves in water slowly and maintains the gas volume, supporting oxygen diffusion. Insects of this type only rarely need to replenish their supply of air. Other aquatic insects can remain under water for long periods due to high concentrations of hemoglobin in their hemolymph circulating freely within their body. Hemoglobin bonds strongly to oxygen molecules. A few insects such as water scorpions and mosquito larvae have breathing tubes ("siphons") with

432-448: The female is on average larger than the male. Males can weigh from 115 to 224 g (4.1 to 7.9 oz), averaging 137 g (4.8 oz) and females from 167 to 290 g (5.9 to 10.2 oz), averaging 261 g (9.2 oz). Alongside the similarly-sized Madagascar jacana , this appears to be the heaviest jacana species. They have chestnut upperparts with black wingtips, rear neck, and eyestripe. The underparts are also chestnut in

459-413: The insect dives into the water, it carries a layer of air over parts of its surface, and breathes using this trapped air bubble until it is depleted, then returns to the surface to repeat the process. Other types of insects have a plastron or physical gill that can be various combinations of hairs, scales, and undulations projecting from the cuticle, which hold a thin layer of air along the outer surface of

486-406: The jacana, as a bird, lays eggs, and eggs can be equally well incubated and cared for by a parent bird of either sex. This means that the rate-limiting factor of the jacana's breeding is the rate at which the males can raise and care for the chicks. Such a system of females forming harems of males is in direct contrast to the more usual system of leks seen in animals such as stags and grouse, where

513-503: The larvae of the holometabolous orders megalopterans and caddisflies, possess tracheal gills, which are outgrowths of the body wall containing a dense network of tracheae covered by a thin cuticle through which oxygen in the water can diffuse. Some insects have densely packed hairs ( setae ) around the spiracles that allow air to remain near, while keeping water away from, the body. The trachea open through spiracles into this air film, allowing access to oxygen. In many such cases, when

540-462: The males compete and display in order to gain harems of females. The parent that forms part of the harem is almost always the one that ends up caring for the offspring; in this case, each male jacana incubates and rears a nest of chicks. The male African jacana has therefore evolved some remarkable adaptations for parental care, such as the ability to pick up and carry chicks underneath its wings. Wader Waders or shorebirds are birds of

567-477: The name 'Waders'). Some species prefer locations with rocks or mud. Many shorebirds display migratory patterns and often migrate before breeding season. These behaviors explain the long wing lengths observed in species, and can also account for the efficient metabolisms that give the birds energy during long migrations . The majority of species eat small invertebrates picked out of mud or exposed soil. Different lengths of bills enable different species to feed in

SECTION 20

#1733122061027

594-473: The opening surrounded by hydrofuge hairs, allowing them to breathe without having to leave the water. EPT insects, an acronym for Ephemeroptera, Plecoptera and Trichoptera (mayflies, stoneflies and caddisflies), are sensitive to pollutants and are used as an indicator of water quality in streams, rivers and lakes. The aquatic insects live mostly in freshwater habitats since there are very few marine insect species. The only true example of such insects are

621-781: The order Charadriiformes commonly found wading along shorelines and mudflats in order to forage for food crawling or burrowing in the mud and sand, usually small arthropods such as aquatic insects or crustaceans . The term "wader" is used in Europe, while "shorebird" is used in North America, where "wader" may be used instead to refer to long-legged wading birds such as storks and herons . There are about 210 species of wader, most of which live in wetland or coastal environments. Many species of Arctic and temperate regions are strongly migratory , but tropical birds are often resident, or move only in response to rainfall patterns. Some of

648-435: The said trait increases the overall fitness of the individual possessing it, then it will be 'selected' and eventually become a permanent part of the population's gene pool. For example, depending on the food available in a shorebird specie's respective niche , bigger bill sizes may be favored in all individuals. This would essentially lead to monomorphism within the species but is subject to change once sexual selection acts on

675-818: The same habitat, particularly on the coast, without direct competition for food. Many waders have sensitive nerve endings at the end of their bills which enable them to detect prey items hidden in mud or soft soil. Some larger species, particularly those adapted to drier habitats will take larger prey including insects and small reptiles . Shorebirds, like many other animals, exhibit phenotypic differences between males and females, also known as sexual dimorphism . In shorebirds, various sexual dimorphisms are seen, including, but not limited to, size (e.g. body size, bill size), color, and agility. In polygynous species, where one male individual mates with multiple female partners over his lifetime, dimorphisms tend to be more diverse. In monogamous species, where male individuals mate with

702-421: The trait. Sexual selection could give rise to males with relatively larger bills than females if males used their bills to compete with other males. If larger bill size assisted the male in gathering resources, it would also make him more attractive to female mates. Aquatic insect One problem that aquatic insects must overcome is how to get oxygen while they are under water. Almost all animals require

729-562: Was introduced in 1925 by the American ornithologist Harry C. Oberholser . The genus name combines the Ancient Greek aktē meaning "river bank" or "coastal strand", -philos meaning "-loving" and ornis meaning "bird". The species is considered to be monotypic : no subspecies are recognised. The African jacanas is a conspicuous and unmistakable bird . It measures 23 to 31 cm (9.1 to 12.2 in) in overall length. As in other jacanas,

#26973