MIGRATION OF ANIMALS...pptx

good for BS hons

1. MIGRATION OF ANIMALS NAME: EHTISHAM SHAFIQUE COLLEGE ROLL NO: 539 University Roll NO: 035975 Subject: Animal Behaviour Submitted To: Prof. Dr. Amir Sab

2. Contents 1 Overview 1.1 Concepts 1.2 Seasonal 1.3 Circadian 1.4 Tidal 1.5 Diel 2 In specific groups 2.1 In birds 2.2 In fish 2.3 In insects 2.4 In mammals 2.5 In other animals 3 Tracking migration

3. 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, 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. A major habitat change could include young  Atlantic salmon  or sea lamprey leaving the river of their birth when they have reached a few inches in size.

4. Concepts: Migration can take very different forms in different species, and has 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 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   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.

5. Seasonal Seasonal migration 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 the winter to escape poor environmental conditions.

6. Circadian 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 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.

7. Tidal Tidal migration is the use of tides by organisms to move periodically from one habitat to another. This type of migration 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 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 the tidal movements. Tidal migration is often facilitated by  ocean currents .

8. Diel 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 .

9. In specific groups Different kinds of animals migrate in different ways. In birds: Approximately 1,800 of 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 kilometer's 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 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 the ability to  detect magnetic fields .

10. In fish 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 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 the east coast of  South Africa  between May and July.

11. In insects: 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 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 . [27] 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 the migration.

12. In mammals: 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). Humans are mammals, but  human migration , as commonly defined, is when individuals often permanently change where they live, which does not fit 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 .

13. In other animals 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 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. They then return to 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.

14. Tracking migration 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 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 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 the bird flies, for analysis on recapture. There is scope for further development of systems able to track small animals globally.

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