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42-605: The Tarangire Ecosystem hosts the second-largest population of migratory ungulates in East Africa and the largest population of elephants in northern Tanzania. The Tarangire Ecosystem is defined by watershed boundaries of the Lake Manyara Basin and the Engaruka Basin, and the long distance migratory movements of eastern white-bearded wildebeest and plains zebra . It includes the dry season wildlife concentration area near

84-546: A basin of internal drainage that lost water through evaporation and deep percolation. Subsequent rises in the Rift Valley floor changed drainage patterns and the lake was reduced in size and divided into the two shallow, alkali lakes currently seen. Topography is now mainly low ridges of gneiss and pre-Cambrian rocks covered with well-drained, medium textured, stony soils. Large areas of valley bottoms are montmorillonite black cotton soils. Ancient lake sediments produced clay soils in

126-409: A fraction of tagged individuals were recovered. More convenient, therefore, are electronic devices such as radio-tracking collars that can be followed by radio, whether handheld, in a vehicle or aircraft, or by satellite. GPS animal tracking enables accurate positions to be broadcast at regular intervals, but the devices are inevitably heavier and more expensive than those without GPS. An alternative

168-474: A greater scale (in both space and time) than its normal daily activities; seasonal to-and-fro movement of a population between two areas; and movement leading to the redistribution of individuals within a population. Migration can be either obligate , meaning individuals must migrate, or facultative, meaning individuals can "choose" to migrate or not. Within a migratory species or even within a single population, often not all individuals migrate. Complete migration

210-568: A variety of causes. As such, there is no simple accepted definition of migration. One of the most commonly used definitions, proposed by the zoologist J. S. Kennedy is Migratory behavior is persistent and straightened-out movement effected by the animal's own locomotory exertions or by its active embarkation on a vehicle. It depends on some temporary inhibition of station-keeping responses, but promotes their eventual disinhibition and recurrence. Migration encompasses four related concepts: persistent straight movement; relocation of an individual on

252-429: Is advantageous in birds that, during the winter, remain close to the equator, and also allows the monitoring of the auditory and spatial memory of the bird's brain to remember an optimal site of migration. These birds also have timing mechanisms that provide them with the distance to their destination. Tidal migration is the use of tides by organisms to move periodically from one habitat to another. This type of migration

294-621: Is also known as the Masai Steppe , or the Tarangire-Manyara Ecosystem . Tarangire has approximately 500 species of birds, and more than 60 species of larger mammal. The area falls within the eastern branch of the East African Rift Valley which has widened and the valley floor fallen over the past few million years. About 250,000 years ago Lake Manyara and Lake Burunge were part of a larger lake called Proto-Manyara,

336-439: Is often used in order to find food or mates. Tides can carry organisms horizontally and vertically for as little as a few nanometres to even thousands of kilometres. The most common form of tidal migration is to and from the intertidal zone during daily tidal cycles. These zones are often populated by many different species and are rich in nutrients. Organisms like crabs, nematodes, and small fish move in and out of these areas as

378-457: Is the Argos Doppler tag, also called a 'Platform Transmitter Terminal' (PTT), which sends regularly to the polar-orbiting Argos satellites; using Doppler shift , the animal's location can be estimated, relatively roughly compared to GPS, but at a lower cost and weight. A technology suitable for small birds which cannot carry the heavier devices is the geolocator which logs the light level as

420-460: Is the movement of various species from one habitat to another during the year. Resource availability changes depending on seasonal fluctuations, which influence migration patterns. Some species such as Pacific salmon migrate to reproduce; every year, they swim upstream to mate and then return to the ocean. Temperature is a driving factor of migration that is dependent on the time of year. Many species, especially birds, migrate to warmer locations during

462-510: Is the rift valley escarpment, the northern boundary is the Kenyan border near Lake Natron, the southern and eastern boundaries are not defined by any strict geographic features. Elevation ranges from about 1000 m in the southwest to 2660 m in the northeast. Tarangire has a bimodal rainfall averaging 650 mm per annum, with short rains from November to February, long rains from March to May, and dry season from June to October. The rains, particularly

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504-441: Is when all individuals migrate, partial migration is when some individuals migrate while others do not, and differential migration is when the difference between migratory and non-migratory individuals is based on discernible characteristics like age or sex. Irregular (non-cyclical) migrations such as irruptions can occur under pressure of famine, overpopulation of a locality, or some more obscure influence. Seasonal migration

546-475: The Antarctic and back again each year, a distance of at least 19,000 km (12,000 mi), giving it two summers every year. Bird migration is controlled primarily by day length, signalled by hormonal changes in the bird's body. On migration, birds navigate using multiple senses. Many birds use a sun compass, requiring them to compensate for the sun's changing position with time of day. Navigation involves

588-522: The Serengeti 'great migration' , an annual circular pattern of movement with some 1.7 million wildebeest and hundreds of thousands of other large game animals, including gazelles and zebra . More than 20 such species engage, or used to engage, in mass migrations. Of these migrations, those of the springbok , black wildebeest , blesbok , scimitar-horned oryx , and kulan have ceased. Long-distance migrations occur in some bats – notably

630-738: The Tarangire River in Tarangire National Park , and the wet-season dispersal and calving grounds to the north in the Northern Plains and to the east in Simanjiro Plains, spanning in total approximately 20,500 km (7,900 sq mi). Migratory animals must have access to both the dry-season water source in the park, and the nutrient-rich forage available only on the calving grounds outside the park to successfully raise their calves and maintain their high abundance. The Tarangire Ecosystem

672-549: The British colonial administration/legislation was adopted by the new government. In the 1960s and 1970s the rinderpest that had previously killed many wildlife and livestock species was controlled. The control of rinderpest resulted in the increased numbers of wildebeest in the Serengeti ecosystem. This pushed Maasai into Tarangire area to avoid contact with wildebeest calving areas in the short grass-plains. Such areas are associated with

714-668: The European farmers/settlers. Many game parks were created at the same time, often evicting pastoralists from key dry season grazing areas and watering points. Because of the abundant water and pasture in the Tarangire ecosystem, it had a reputation as one of the best pastoral areas in Tanzania. Many herders who were evicted from the Serengeti National Park in the 1950s relocated to this area. Tanzania became independent in 1961 and most of

756-587: The Maa-speaking pastoral people expanded into the area, replacing other pastoral groups like Nilotes and farming Bantu groups. By 1880 the Maasai reached their greatest extent. Around 1900 they suffered pleuro-pneumonia and smallpox diseases that killed many. At the same time the outbreak of the rinderpest decimated Maasai livestock and wildlife. The colonial period of 1880s to 1950s saw the displacement of Maasai from lands with high potential for agricultural development by

798-551: The North Atlantic ocean. The capelin, for example, spawn around the southern and western coasts of Iceland; their larvae drift clockwise around Iceland, while the fish swim northwards towards Jan Mayen island to feed and return to Iceland parallel with Greenland's east coast. In the ' sardine run ', billions of Southern African pilchard Sardinops sagax spawn in the cold waters of the Agulhas Bank and move northward along

840-540: The Northern Plains. 3°50′0″S 36°00′0″E  /  3.83333°S 36.00000°E  / -3.83333; 36.00000 Animal migration Animal migration is the relatively long-distance movement of individual animals , usually on a seasonal basis. It is the most common form of migration in ecology. It is found in all major animal groups, including birds , mammals , fish , reptiles , amphibians, insects , and crustaceans . The cause of migration may be local climate, local availability of food,

882-521: The Proto-Manyara area. Minjingu Hill and Vilima Vitatu were islands in Proto-Manyara Lake and their phosphate deposits there are derived from accumulated waterbird feces. Volcanic ash deposits produce rich soils on the Northern Plains and Simanjiro Plains where migratory wildebeest and zebra find forage with the nutrients necessary for lactation and healthy calf growth. The current western boundary

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924-517: The ability to detect magnetic fields . Most fish species are relatively limited in their movements, remaining in a single geographical area and making short migrations to overwinter, to spawn , or to feed. A few hundred species migrate long distances, in some cases of thousands of kilometres. About 120 species of fish, including several species of salmon , migrate between saltwater and freshwater (they are 'diadromous'). Forage fish such as herring and capelin migrate around substantial parts of

966-700: The best rangelands into more marginal areas. In 1970, the Tarangire Game Reserve was upgraded to become Tarangire National Park. By the mid-1980s the movement of commercial interests and farmers into the area had expanded, blocking many traditional migratory routes for wildlife. In 2001, the Tanzanian government turned over the National Ranching Company land at Manyrara Ranch to the Tanzania Land Conservation Trust to help conserve

1008-511: The bird flies, for analysis on recapture. There is scope for further development of systems able to track small animals globally. Radio-tracking tags can be fitted to insects, including dragonflies and bees . Before animal migration was understood, various folklore and erroneous explanations were formulated to account for the disappearance or sudden arrival of birds in an area. In Ancient Greece , Aristotle proposed that robins turned into redstarts when summer arrived. The barnacle goose

1050-568: The desert locust, Schistocerca gregaria , flew westwards across the Atlantic Ocean for 4,500 kilometres (2,800 mi) during October 1988, using air currents in the Inter-Tropical Convergence Zone . In some migratory butterflies , such as the monarch butterfly and the painted lady , no individual completes the whole migration. Instead, the butterflies mate and reproduce on the journey, and successive generations continue

1092-468: The east coast of South Africa between May and July. Some winged insects such as locusts and certain butterflies and dragonflies with strong flight migrate long distances. Among the dragonflies, species of Libellula and Sympetrum are known for mass migration, while Pantala flavescens , known as the globe skimmer or wandering glider dragonfly, makes the longest ocean crossing of any insect: between India and Africa. Exceptionally, swarms of

1134-475: The length of the wet season. For example, the wet season lasted 38 days in 1983/1984 and 200 days in 1987/1988. The oldest known elephant to give birth to twins is found in Tarangire. A recent birth of elephant twins in the Tarangire National Park of Tanzania is a great example of how the birth of these two healthy and thriving twins can beat the odds. Between the sixteenth and nineteenth centuries,

1176-450: The mass migration of the Mexican free-tailed bat between Oregon and southern Mexico. Migration is important in cetaceans , including whales, dolphins and porpoises; some species travel long distances between their feeding and their breeding areas. Humans are mammals, but human migration , as commonly defined, is when individuals often permanently change where they live, which does not fit

1218-476: The migration. Some mammals undertake exceptional migrations; reindeer have one of the longest terrestrial migrations on the planet, reaching as much as 4,868 kilometres (3,025 mi) per year in North America. However, over the course of a year, grey wolves move the most. One grey wolf covered a total cumulative annual distance of 7,247 kilometres (4,503 mi). Mass migration occurs in mammals such as

1260-509: The open sea. Juvenile green sea turtles make use of Earth's magnetic field to navigate. Some crustaceans migrate, such as the largely-terrestrial Christmas Island red crab , which moves en masse each year by the millions. Like other crabs, they breathe using gills, which must remain wet, so they avoid direct sunlight, digging burrows to shelter from the sun. They mate on land near their burrows. The females incubate their eggs in their abdominal brood pouches for two weeks. Then they return to

1302-436: The patterns described here. An exception is some traditional migratory patterns such as transhumance , in which herders and their animals move seasonally between mountains and valleys, and the seasonal movements of nomads . Among the reptiles, adult sea turtles migrate long distances to breed, as do some amphibians. Hatchling sea turtles, too, emerge from underground nests, crawl down to the water, and swim offshore to reach

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1344-536: The river of their birth when they have reached a few inches in size. Some traditional forms of human migration fit this pattern. Migrations can be studied using traditional identification tags such as bird rings , or tracked directly with electronic tracking devices. Before animal migration was understood, folklore explanations were formulated for the appearance and disappearance of some species, such as that barnacle geese grew from goose barnacles . Migration can take very different forms in different species, and has

1386-424: The sea to release their eggs at high tide in the moon's last quarter. The larvae spend a few weeks at sea and then return to land. Scientists gather observations of animal migration by tracking their movements. Animals were traditionally tracked with identification tags such as bird rings for later recovery. However, no information was obtained about the actual route followed between release and recovery, and only

1428-473: The season of the year or for mating. To be counted as a true migration, and not just a local dispersal or irruption, the movement of the animals should be an annual or seasonal occurrence, or a major habitat change as part of their life. An annual event could include Northern Hemisphere birds migrating south for the winter, or wildebeest migrating annually for seasonal grazing. A major habitat change could include young Atlantic salmon or sea lamprey leaving

1470-400: The short rains, are very unreliable and often fail. Rainfall varies inter-annually, the standard deviation of the annual rainfall is equal to 37% of the mean annual rainfall. The inter-annual variation of monthly rainfall varies even more markedly, the standard deviation of monthly rainfall is 72% of the mean. This high variability in rainfall is also reflected in a high inter-annual variation of

1512-719: The spread of Malignant Catarrhal Fever that affects cattle. Between 1962 and 1963 the worst drought in 50 years hit most parts of the country including Tarangire area and killed many wildlife and livestock. In 1967 agriculture was promoted as the backbone of the national economy. Large-scale farms like the Lolkisale bean farms were established in Tarangire to produce crops for export as well as for national reserves during droughts and food shortage. Human population increased in Tarangire area due both to natural increase and immigration of agriculturists from nearby regions of Kilimanjaro and Arusha. This displaced Maasai pastoralists and wildlife from

1554-473: The tidal movements. Tidal migration is often facilitated by ocean currents . While most migratory movements occur on an annual cycle, some daily movements are also described as migration. Many aquatic animals make a diel vertical migration , travelling a few hundred metres up and down the water column, while some jellyfish make daily horizontal migrations of a few hundred metres. Different kinds of animals migrate in different ways. Approximately 1,800 of

1596-403: The tides rise and fall, typically about every twelve hours. The cycle movements are associated with foraging of marine and bird species. Typically, during low tide, smaller or younger species will emerge to forage because they can survive in the shallower water and have less chance of being preyed upon. During high tide, larger species can be found due to the deeper water and nutrient upwelling from

1638-470: The wildlife migration corridor between Tarangire National Park and the calving grounds to the north on the Gelai Plains. Conservation easements are being used as conservation tools on the calving grounds east of Tarangire National Park on the Simanjiro Plains. Land-use planning informed by wildlife survey data is being tried to help conserve pastoral rangelands, wildlife migration routes, and calving grounds in

1680-399: The winter to escape poor environmental conditions. Circadian migration is where birds utilise circadian rhythm (CR) to regulate migration in both fall and spring. In circadian migration, clocks of both circadian (daily) and circannual (annual) patterns are used to determine the birds' orientation in both time and space as they migrate from one destination to the next. This type of migration

1722-538: The world's 10,000 bird species migrate long distances each year in response to the seasons. Many of these migrations are north-south, with species feeding and breeding in high northern latitudes in the summer and moving some hundreds of kilometres south for the winter. Some species extend this strategy to migrate annually between the Northern and Southern Hemispheres. The Arctic tern has the longest migration journey of any bird: it flies from its Arctic breeding grounds to

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1764-479: Was explained in European Medieval bestiaries and manuscripts as either growing like fruit on trees, or developing from goose barnacles on pieces of driftwood. Another example is the swallow , which was once thought, even by naturalists such as Gilbert White , to hibernate either underwater, buried in muddy riverbanks, or in hollow trees. Rinderpest Too Many Requests If you report this error to

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