44 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 trigger for the migration may be local climate, local availability of food, the season of the year or for mating reasons. 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, such as Northern Hemisphere birds migrating south for the winter; wildebeest migrating annually for seasonal grazing; or a major habitat change as part of their life, such as young Atlantic salmon or sea lamprey leaving the river of their birth when they have reached a few inches in size.

Migration, in ecology, is the large-scale movement of members of a species to a different environment. Migration is a natural behavior and component of the life cycle of many species of mobile organisms, not limited to animals, though animal migration is the best known type. Migration is often cyclical, frequently occurring on a seasonal basis, and in some cases on a daily basis. Species migrate to take advantage of more favorable conditions with respect to food availability, safety from predation, mating opportunity, or other environmental factors.

Altitudinal migration is a short-distance animal migration from lower altitudes to higher altitudes and back. It is commonly thought to happen in response to climate and food availability changes as well as increasingly due to anthropogenic influence. These migrations can occur both during reproductive and non-reproductive seasons. Altitudinal avian migration is common, and can also be found in other vertebrates, and can be seen in some invertebrates.

Animal migration tracking is used in wildlife biology, conservation biology, ecology, and wildlife management to study animals' behavior in the wild. One of the first techniques was bird banding, placing passive ID tags on birds legs, to identify the bird in a future catch-and-release. Radio tracking involves attaching a small radio transmitter to the animal and following the signal with a RDF receiver. Sophisticated modern techniques use satellites to track tagged animals, and GPS tags which keep a log of the animal's location. One of the many goals of animal migration research has been to determine where the animals are going; however, researchers also want to know why they are going "there". Researchers not only look at the animals' migration but also what is between the migration endpoints to determine if a species is moving to new locations based on food density, a change in water temperature, or other stimulus, and the animal's ability to adapt to these changes. Migration tracking is a vital tool in efforts to control the impact of human civilization on populations of wild animals, and prevent or mitigate the ongoing extinction of endangered species.

Animal navigation is the ability of many animals to find their way accurately without maps or instruments. Birds such as the Arctic tern, insects such as the monarch butterfly and fish such as the salmon regularly migrate thousands of miles to and from their breeding grounds, and many other species navigate effectively over shorter distances.

The bogong moth is a temperate species of night-flying moth, notable for its biannual long-distance seasonal migrations towards and from the Australian Alps, similar to the diurnal monarch butterfly. During the autumn and winter it is found in southern Queensland, western New South Wales, western Victoria, and also in South and Western Australia. Adult bogong moths breed and larvae hatch during this period, consuming winter pasture plants during their growth. During the spring, the moths migrate south or east and reside in mountains such as Mount Bogong, where they gregariously aestivate over the summer until their return towards breeding grounds again in the autumn.

A butterfly count is an event that is organized for the purpose of identifying and counting butterflies in a specific geographical area. Butterfly counts occur regularly in North America and Europe.

The desert locust is a species of locust, a periodically swarming, short-horned grasshopper in the family Acrididae. They are found mainly in Africa, through Arabia and West Asia, and extending into parts of South Asia. During population surge years, they may extend into parts of western Spain. The desert locust shows periodic changes in its body form and can change, in response to environmental conditions, over generations, from a solitary, shorter-winged, highly fecund, nonmigratory form to a gregarious, long-winged, and migratory phase in which they may travel long distances into new areas. In some years, they may thus form locust plagues, invading new areas, where they may consume all vegetation including crops, and at other times, they may live unnoticed in small numbers.

Diel vertical migration (DVM), also known as diurnal vertical migration, is a pattern of movement used by some organisms, such as copepods, living in the ocean and in lakes. The migration occurs when organisms move up to the uppermost layer of the sea at night and return to the bottom of the daylight zone of the oceans or to the dense, bottom layer of lakes during the day. The word diel comes from the Latin dies day, and means a 24-hour period. In terms of biomass, it is the greatest migration in the world. It is not restricted to any one taxon as examples are known from crustaceans (copepods), molluscs (squid), and ray-finned fishes (trout). Various stimuli are responsible for this phenomenon, the most prominent being response to changes in light intensity, though evidence suggests that biological clocks are an underlying stimulus as well. The phenomenon may arise for a number of reasons, though it is most typically to access food and avoid predators. While this mass migration is generally nocturnal, with the animals ascending from the depths at nightfall and descending at sunrise, the timing can be altered in response to the different cues and stimuli that trigger it. Some unusual events impact vertical migration: DVM is absent during the midnight sun in Arctic regions and vertical migration can occur suddenly during a solar eclipse.

A drift fence is any long, continuous fence used to control the movement of animals in a particular open range, or to collect animals for research.

Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few metres to thousands of kilometres. Fish usually migrate to feed or to reproduce, but in other cases the reasons are unclear.

Great Migrations is a seven-episode nature documentary television miniseries that airs on the National Geographic Channel, featuring the great migrations of animals around the globe. The seven-part show is the largest programming event in the ten-year history of the channel and is part of the largest cross-platform initiative since the founding of the National Geographic Society. It was filmed in HD, and premiered on November 7, 2010 with accompanying coverage in the National Geographic magazine and an official companion book.

Herding is the act of bringing individual animals together into a group (herd), maintaining the group, and moving the group from place to place—or any combination of those. Herding can refer either to the process of animals forming herds in the wild, or to human intervention forming herds for some purpose. While the layperson uses the term "herding" to describe this human intervention, most individuals involved in the process term it mustering, "working stock", or droving.

Homing is the inherent ability of an animal to navigate towards an original location through unfamiliar areas. This location may be either a home territory, or a breeding spot.

The hummingbird hawk-moth is a species of moth. It was first described by Carl Linnaeus in his 1758 10th edition of Systema Naturae. As of 2018, its entire genome and mitogenome have been sequenced.

Insect migration is the seasonal movement of insects, particularly those by species of dragonflies, beetles, butterflies and moths. The distance can vary with species and in most cases these movements involve large numbers of individuals. In some cases the individuals that migrate in one direction may not return and the next generation may instead migrate in the opposite direction. This is a significant difference from bird migration.

Kasanka National Park is a park located in the Serenje District of Zambia’s Central Province. At roughly 390 km2 (150 sq mi), Kasanka is one of Zambia’s smallest national parks. Kasanka was the first of Zambia’s national parks to be managed by a private-public partnership. The privately funded Kasanka Trust Ltd has been in operation since 1986 and undertakes all management responsibilities, in partnership with the Department of National Parks and Wildlife. The park has an average elevation between 1,160 m (3,810 ft) and 1,290 m (4,230 ft) above mean sea level. It has a number permanent shallow lakes and water bodies with the largest being Wasa. There are five perennial rivers in the park, with the largest being the Luwombwa River. The Luwombwa is the only river that drains the NP, which flows out in the northwestern corner. It is a tributary of the Luapula, which further upstream also drains the Bangweulu Swamp and forms the main source of the Congo River. Although Kasanka NP is part of the Greater Bangweulu Ecosystem, there is no direct hydrological connection between the park and the Bangweulu Wetlands.

Many populations of Lepidoptera migrate, sometimes long distances, to and from areas which are only suitable for part of the year. Lepidopterans migrate on all continents except Antarctica, including from or within subtropical and tropical areas. By migrating, these species can avoid unfavorable circumstances, including weather, food shortage, or over-population. In some lepidopteran species, all individuals migrate; in others, only some migrate.

The Levantine corridor is the relatively narrow strip between the Mediterranean Sea to the northwest and deserts to the southeast which connects Africa to Eurasia. This corridor is a land route of migrations of animals between Eurasia and Africa. In particular, it is believed that early hominins spread from Africa to Eurasia via the Levantine corridor and Horn of Africa. The corridor is named after the Levant.

Libellula is a genus of dragonflies, commonly called skimmers, in the family Libellulidae, distributed throughout the temperate zone of the Northern Hemisphere. Most species are found in the United States, where they are the best-known large dragonflies, often seen flying over freshwater ponds in summer. Many have showy wing patterns.

The McArthur Lake Wildlife Corridor (MLWC) is a wildlife corridor in northern Idaho, United States. It links the wilderness areas of the Selkirk and Cabinet mountains, and is used by species such as grizzly bears that move between these areas. It also provides a wintering area for deer and other ungulates. A highway and two railway lines run through the corridor, with a strip of side roads, buildings and fences along the highway. The highway section running through the corridor has high rates of vehicle collisions with wildlife. There is limited opportunity for creating safe wildlife crossings due to the difficult terrain. Conservation groups have been active in obtaining easements on timber land to prevent further development in the corridor while allowing sustainable forestry.

The world's oceans are warming due to climate change. Climate change is caused by three major factors which are the greenhouse effect, variation in the sun's energy that reaches Earth, and changes in reflectivity within Earth's atmosphere and its surface. The greenhouse effect is caused by greenhouse gases that absorb sunlight. Energy from the sun that reaches Earth is either retained or sent into space. Greenhouse gases in Earth's atmosphere such as carbon dioxide, methane, and water vapor absorb energy which cause a blanketing effect that warms the earth. Aerosols such as black carbon also catalyze the warming effect as they are unreflective and absorb energy from the sun supplementing greenhouse gases in the warming effect.

The migratory locust is the most widespread locust species, and the only species in the genus Locusta. It occurs throughout Africa, Asia, Australia and New Zealand. It used to be common in Europe but has now become rare there. Because of the vast geographic area it occupies, which comprises many different ecological zones, numerous subspecies have been described. However, not all experts agree on the validity of some of these subspecies.

The monarch butterfly or simply monarch is a milkweed butterfly in the family Nymphalidae. Other common names, depending on region, include milkweed, common tiger, wanderer, and black veined brown. It may be the most familiar North American butterfly, and is considered an iconic pollinator species. Its wings feature an easily recognizable black, orange, and white pattern, with a wingspan of 8.9–10.2 cm (3 1⁄2–4 in) A Müllerian mimic, the viceroy butterfly, is similar in color and pattern, but is markedly smaller and has an extra black stripe across each hindwing.

Monarch butterfly migration is the phenomenon, mainly across North America, where the subspecies Danaus plexippus plexippus migrates each summer and autumn to and from overwintering sites on the West Coast of California or mountainous sites in Central Mexico. Other subspecies perform minor migrations or none at all. This massive movement of butterflies has been called "one of the most spectacular natural phenomena in the world".

Monarch Watch is a volunteer-based citizen science organization that tracks the fall migration of the monarch butterfly. It is self-described as "a nonprofit education, conservation, and research program based at the University of Kansas that focuses on the monarch butterfly, its habitat, and its spectacular fall migration."

Olfactory navigation is a hypothesis put forward to explain navigation and homing of pigeons, in particular the homing pigeon.

Path integration is the method thought to be used by animals for dead reckoning.

A pest-exclusion fence is a barrier that is built to exclude certain types of animal pests from an enclosure. This may be to protect plants in horticulture, preserve grassland for grazing animals, separate species carrying diseases from livestock, prevent troublesome species entering roadways, or to protect endemic species in nature reserves. These fences are not necessarily traditional wire barriers, but may also include barriers of sound, or smell.

The State Barrier Fence of Western Australia, formerly known as the Rabbit Proof Fence, the State Vermin Fence, and the Emu Fence, is a pest-exclusion fence constructed between 1901 and 1907 to keep rabbits and other agricultural pests, from the east, out of Western Australian pastoral areas.

The reindeer is a widespread and numerous species in the northern Holarctic, being present in both tundra and taiga. Originally, the reindeer was found in Scandinavia, eastern Europe, Russia, Mongolia, and northern China north of the 50th latitude. In North America, it was found in Canada, Alaska, and the northern conterminous USA from Washington to Maine. In the 19th century, it was apparently still present in southern Idaho. It also occurred naturally on Sakhalin, Greenland, and probably even in historical times in Ireland. During the late Pleistocene era, reindeer were found as far south as Nevada and Tennessee in North America and Spain in Europe. Today, wild reindeer have disappeared from many areas within this large historical range, especially from the southern parts, where it vanished almost everywhere. Populations of wild reindeer are still found in Norway, Finland, Siberia, Greenland, Alaska, and Canada.

The Sahara pump theory is a hypothesis that explains how flora and fauna migrated between Eurasia and Africa via a land bridge in the Levant region. It posits that extended periods of abundant rainfall lasting many thousands of years in Africa are associated with a "wet-Sahara" phase, during which larger lakes and more rivers existed. This caused changes in the flora and fauna found in the area. Migration along the river corridor was halted when, during a desert phase 1.8–0.8 million years ago (mya), the Nile ceased to flow completely and possibly flowed only temporarily in other periods due to the geologic uplift of the Nile River region.

Sea turtle migration refers to the long-distance movements of sea turtles notably as adults but may also refer to the offshore migration of hatchings. Sea turtle hatchings emerge from underground nests and crawl across the beach towards the sea. They then maintain an offshore heading until they reach the open sea. The feeding and nesting sites of adult sea turtles are often distantly separated meaning some must migrate hundreds or even thousands of kilometres.

The silver Y is a migratory moth of the family Noctuidae which is named for the silvery Y-shaped mark on each of its forewings.

Species distribution is the manner in which a biological taxon is spatially arranged. The geographic limits of a particular taxon's distribution is its range, often represented as shaded areas on a map. Patterns of distribution change depending on the scale at which they are viewed, from the arrangement of individuals within a small family unit, to patterns within a population, or the distribution of the entire species as a whole (range). Species distribution is not to be confused with dispersal, which is the movement of individuals away from their region of origin or from a population center of high density.

Swarm behaviour, or swarming, is a collective behaviour exhibited by entities, particularly animals, of similar size which aggregate together, perhaps milling about the same spot or perhaps moving en masse or migrating in some direction. It is a highly interdisciplinary topic. As a term, swarming is applied particularly to insects, but can also be applied to any other entity or animal that exhibits swarm behaviour. The term flocking or murmuration can refer specifically to swarm behaviour in birds, herding to refer to swarm behaviour in tetrapods, and shoaling or schooling to refer to swarm behaviour in fish. Phytoplankton also gather in huge swarms called blooms, although these organisms are algae and are not self-propelled the way animals are. By extension, the term "swarm" is applied also to inanimate entities which exhibit parallel behaviours, as in a robot swarm, an earthquake swarm, or a swarm of stars.

Swarming is a honey bee colony's natural means of reproduction. In the process of swarming, a single colony splits into two or more distinct colonies.

Sympetrum is a genus of small to medium-sized skimmer dragonflies, known as darters in the UK and as meadowhawks in North America. The more than 50 species predominantly live in the temperate zone of the Northern Hemisphere; no Sympetrum species is native to Australia.

Tracking collars are collars used as a radio beacon to track animal migration for research. Some pet owners use these collars for GPS tracking and geofencing of their pets.

Vagrancy is a phenomenon in biology whereby individual animals appear well outside their normal range; individual animals which exhibit vagrancy are known as vagrants. The term accidental is sometimes also used. There are a number of factors which might cause an individual to become a vagrant—genetic factors and weather conditions are two—but the causes are overall poorly understood. Vagrancy can be a precursor to colonisation if individuals survive.

Vanessa atalanta, the red admiral or, previously, the red admirable, is a well-characterized, medium-sized butterfly with black wings, red bands, and white spots. It has a wingspan of about 2 inches (5 cm). It was first described by Carl Linnaeus in his 1758 10th edition of Systema Naturae. The red admiral is widely distributed across temperate regions of North Africa, the Americas, Europe, Asia, and the Caribbean. It resides in warmer areas, but migrates north in spring and sometimes again in autumn. Typically found in moist woodlands, the red admiral caterpillar's primary host plant is the stinging nettle ; it can also be found on the false nettle. The adult butterfly drinks from flowering plants like Buddleia and overripe fruit. Red admirals are territorial; females will only mate with males that hold territory. Males with superior flight abilities are more likely to successfully court females. It is known as an unusually calm butterfly, often allowing observation at a very close distance before flying away, also landing on and using humans as perches.

Vanessa cardui is a well-known colourful butterfly, known as the painted lady, or formerly in North America as the cosmopolitan.

A wildlife corridor, habitat corridor, or green corridor is an area of habitat connecting wildlife populations separated by human activities or structures. This allows an exchange of individuals between populations, which may help prevent the negative effects of inbreeding and reduced genetic diversity that often occur within isolated populations. Corridors may also help facilitate the re-establishment of populations that have been reduced or eliminated due to random events.

Wolf distribution is the species distribution of the wolf. Originally, wolves occurred in Eurasia above the 12th parallel north and in North America above the 15th parallel north. However, deliberate human persecution has reduced the species' range to about one-third, because of livestock predation and fear of wolf attacks on humans. The species is now extirpated in much of Western Europe, in Mexico, and much of the United States. In modern history, the gray wolf occurs mostly in wilderness and remote areas, particularly in Canada, Alaska and the Northern United States, Europe and Asia from about the 75th parallel north to the 12th parallel north. Wolf population declines have been arrested since the 1970s, and have fostered recolonization and reintroduction in parts of its former range, due to legal protection, changes in land-use and rural human population shifts to cities. Competition with humans for livestock and game species, concerns over the danger posed by wolves to people, and habitat fragmentation pose a continued threat to the species. Despite these threats, because of the gray wolf's relatively widespread range and stable population, it is classified as Least Concern on the IUCN Red List.