Hi Everybody!!
Bird Migration is in progress. I have shared an excerpt info from Wikipedia to give you a little background on the Migration, but check out the link for complete article. On the map below, I am on the pink line in Texas close to the Gulf of Mexico. My location is good for viewing the birds as they fly over or stop off for awhile to eat. I have shared pics for 5 years now of the different migrants (See my G+ Web Album Gallery). The most favorite migrant for my viewers is the Hummingbird! They usually arrive on August 12 and stay thru October. Last Thanksgiving one showed up after the others were gone. He has stayed all winter. Your photostudy tonight is of this little hummer as of yesterday. He is still here and enjoying all the flowers.
Enjoy and feed your birds!
https://en.wikipedia.org/wiki/Hummingbird
Hummingbird
From Wikipedia, the free encyclopedia
| Hummingbirds | |
|---|---|
 | |
| Female Black-chinned Hummingbird | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Subclass: | Neornithes |
| Infraclass: | Neognathae |
| (unranked): | Cypselomorphae |
| Order: | Apodiformes |
| Family: | Trochilidae |
Hummingbirds are New World birds that constitute the family Trochilidae. They are among the smallest of birds, most species measuring in the 7.5–13 cm (3–5 in) range. Indeed, the smallest extant bird species is a hummingbird, the 5-cm Bee Hummingbird.
They are known as hummingbirds because of the humming sound created by their beating wings which flap at high frequencies audible to humans. They hover in mid-air at rapid wing flapping rates, typically around 50 times per second,[1] but possibly as high as 200 times per second, allowing them also to fly at speeds exceeding 15 m/s (54 km/h; 34 mph),[2] backwards or upside down.[3][4]
Hummingbirds have the highest metabolism of any homeothermic animal.[5] To conserve energy when food is scarce, they have the ability to go into a hibernation-like state (torpor) where their metabolic rate is slowed to 1/15th of its normal rate.[6]The smallest species of hummingbird weighs less than a penny.
https://plus.google.com/u/0/photos/117645114459863049265/albums/6012519454089224625
https://en.wikipedia.org/wiki/Bird_migration
Bird migration
From Wikipedia, the free encyclopedia
Examples of long distance bird migration routes.
Bird migration is the regular seasonal movement, often north and south along a flyway between breeding and wintering grounds, undertaken by many species of birds. Migration, which carries high costs in predation and mortality, including from hunting by humans, is driven primarily by availability of food. Migration occurs mainly in the Northern Hemisphere where birds are funnelled on to specific routes by natural barriers such as the Mediterranean Sea or the Caribbean Sea.
Historically, migration has been recorded as much as 3,000 years ago by Ancient Greek authors including Homer and Aristotle, and in theBook of Job, for species such as storks, Turtle Doves, and swallows. More recently, Johannes Leche began recording dates of arrivals of spring migrants in Finland in 1749, and scientific studies have used techniques including bird ringing and satellite tracking. Threats to migratory birds have grown with habitat destruction especially of stopover and wintering sites, as well as structures such as power lines and wind farms.
The Arctic Tern holds the long-distance migration record for birds, travelling between Arctic breeding grounds and the Antarctic each year. Some species of tubenoses (Procellariiformes) such as albatrossescircle the earth, flying over the southern oceans, while others such asManx Shearwaters migrate 14,000 km (8,700 mi) between their northern breeding grounds and the southern ocean. Shorter migrations are common, including altitudinal migrations on mountains such as the Andes and Himalayas.
The timing of migration is controlled primarily by changes in day length. Migrating birds navigate using celestial cues from the sun and stars, the earth's magnetic field, and probably also mental maps. Migration has developed independently in different groups of birds and does not appear to require genetic change; some birds have acquired migratory behaviour since the last ice age.
General patterns[edit]
Migration is the regular seasonal movement, often north and south, undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat, or weather. Sometimes, journeys are not termed "true migration" because they are irregular (nomadism, invasions, irruptions) or in only one direction (dispersal, movement of young away from natal area). Migration is marked by its annual seasonality.[1] Non-migratory birds are said to be resident or sedentary. Approximately 1800 of the world's 10,000 bird species are long-distance migrants.[2]
Many bird populations migrate long distances along a flyway. The most common pattern involves flying north in the spring to breed in the temperate or Arctic summer and returning in the autumn to wintering grounds in warmer regions to the south. Of course, in the Southern Hemisphere the directions are reversed, but there is less land area in the far South to support long-distance migration.[3]
The primary motivation for migration appears to be food; for example, some hummingbirds choose not to migrate if fed through the winter.[4] Also, the longer days of the northern summer provide extended time for breeding birds to feed their young. This helps diurnal birds to produce larger clutches than related non-migratory species that remain in the tropics. As the days shorten in autumn, the birds return to warmer regions where the available food supply varies little with the season.[5]
These advantages offset the high stress, physical exertion costs, and other risks of the migration such as predation. Predation can be heightened during migration: theEleonora's Falcon, which breeds on Mediterranean islands, has a very late breeding season, coordinated with the autumn passage of southbound passerine migrants, which it feeds to its young. A similar strategy is adopted by the Greater Noctule bat, which preys on nocturnal passerine migrants.[6][7][8] The higher concentrations of migrating birds at stopover sites make them prone to parasites and pathogens, which require a heightened immune response.[3]
Within a species not all populations may be migratory; this is known as "partial migration". Partial migration is very common in the southern continents; in Australia, 44% of non-passerine birds and 32% of passerine species are partially migratory.[9] In some species, the population at higher latitudes tends to be migratory and will often winter at lower latitude. The migrating birds bypass the latitudes where other populations may be sedentary, where suitable wintering habitats may already be occupied. This is an example of leap-frog migration.[10] Many fully migratory species show leap-frog migration (birds that nest at higher latitudes spend the winter at lower latitudes), and many show the alternative, chain migration, where populations 'slide' more evenly North and South without reversing order.[11]
Within a population, it is common for different ages and/or sexes to have different patterns of timing and distance. FemaleChaffinches in Eastern Fennoscandia migrate earlier in the autumn than males do.[12]
Most migrations begin with the birds starting off in a broad front. Often, this front narrows into one or more preferred routes termed flyways. These routes typically follow mountain ranges or coastlines, sometimes rivers, and may take advantage of updrafts and other wind patterns or avoid geographical barriers such as large stretches of open water. The specific routes may be genetically programmed or learned to varying degrees. The routes taken on forward and return migration are often different.[3] A common pattern in North America is clockwise migration, where birds flying North tend to be further West, and flying South tend to shift Eastwards.
Many, if not most, birds migrate in flocks. For larger birds, flying in flocks reduces the energy cost. Geese in a V-formation may conserve 12–20% of the energy they would need to fly alone.[13][14] Red Knots Calidris canutus and Dunlins Calidris alpina were found in radar studies to fly 5 km per hour faster in flocks than when they were flying alone.[3]
Birds fly at varying altitudes during migration. An expedition to Mt. Everest found skeletons of Pintail and Black-tailed Godwitat 5000 m (16,400 ft) on the Khumbu Glacier.[15] Bar-headed Geese have been recorded by GPS flying at up to 6,540 metres while crossing the Himalayas, at the same time engaging in the highest rates of climb to altitude for any bird. Anecdotal reports of them flying much higher have yet to be corroborated with any direct evidence.[16] Seabirds fly low over water but gain altitude when crossing land, and the reverse pattern is seen in landbirds.[17][18] However most bird migration is in the range of 150 m (500 ft) to 600 m (2000 ft). Bird strike aviation records from the United States show most collisions occur below 600 m (2000 ft) and almost none above 1800 m (6000 ft).[19]
Bird migration is not limited to birds that can fly. Most species of penguin migrate by swimming. These routes can cover over 1000 km. Blue Grouse Dendragapus obscurus perform altitudinal migration mostly by walking. Emus in Australia have been observed to undertake long-distance movements on foot during droughts.[3]
Long-distance migration[edit]
The typical image of migration is of northern landbirds, such as swallows and birds of prey, making long flights to the tropics. However, many Holarctic wildfowl and finchspecies winter in the North Temperate Zone, but in regions with milder winters than their summer breeding grounds. For example, the pink-footed goose migrates fromIceland to Britain and neighbouring countries, whilst the Dark-Eyed Junco migrates from subarctic and arctic climates to the contiguous United States[27] and the American Goldfinch from taiga to wintering grounds extending from the American South northwestward to Western Oregon.[28] Migratory routes and wintering grounds are traditional and learned by young during their first migration with their parents. Some ducks, such as the Garganey, move completely or partially into the tropics. The European pied flycatcher also follows this migratory trend, breeding in Asia and Europe and wintering in Africa.
The same considerations about barriers and detours that apply to long-distance land-bird migration apply to water birds, but in reverse: a large area of land without bodies of water that offer feeding sites is a barrier to may also be a barrier to a bird that feeds in coastal waters. Detours avoiding such barriers are observed: for example, Brent Geese migrating from the Taymyr Peninsula to the Wadden Seatravel via the White Sea coast and the Baltic Sea rather than directly across the Arctic Ocean and northern Scandinavia.[29]
A similar situation occurs with waders (called shorebirds in North America). Many species, such as Dunlin and Western Sandpiper, undertake long movements from their Arctic breeding grounds to warmer locations in the same hemisphere, but others such as Semipalmated Sandpiper travel longer distances to the tropics in the Southern Hemisphere. Like the large and powerful wildfowl, the waders are strong fliers. This means that birds wintering in temperate regions have the capacity to make further shorter movements in the event of particularly inclement weather.[citation needed]
For some species of waders, migration success depends on the availability of certain key food resources at stopover points along the migration route. This gives the migrants an opportunity to refuel for the next leg of the voyage. Some examples of important stopover locations are the Bay of Fundy and Delaware Bay.[30][31]
Some Bar-tailed Godwits have the longest known non-stop flight of any migrant, flying 11,000 km from Alaska to their New Zealand non-breeding areas.[32] Prior to migration, 55 percent of their bodyweight is stored fat to fuel this uninterrupted journey.
Seabird migration is similar in pattern to those of the waders and waterfowl. Some, such as the Black Guillemot and some gulls, are quite sedentary; others, such as most terns and auks breeding in the temperate northern hemisphere, move varying distances south in the northern winter. The Arctic Tern has the longest-distance migration of any bird, and sees more daylight than any other, moving from its Arctic breeding grounds to the Antarctic non-breeding areas. One Arctic Tern, ringed(banded) as a chick on the Farne Islands off the British east coast, reachedMelbourne, Australia in just three months from fledging, a sea journey of over 22,000 km (14,000 mi). A few seabirds, such as Wilson's Petrel and Great Shearwater, breed in the southern hemisphere and migrate north in the southern winter. Seabirds have the additional advantage of being able to feed during migration over open waters.[citation needed]
The most pelagic species, mainly in the 'tubenose' order Procellariiformes, are great wanderers, and the albatrosses of the southern oceans may circle the globe as they ride the "roaring forties" outside the breeding season. The tubenoses spread widely over large areas of open ocean, but congregate when food becomes available. Many are also among the longest-distance migrants; Sooty Shearwaters nesting on the Falkland Islands migrate 14,000 km (8,700 mi) between the breeding colony and the North Atlantic Ocean off Norway. Some Manx Shearwaters do this same journey in reverse. As they are long-lived birds, they may cover enormous distances during their lives; one record-breaking Manx Shearwater is calculated to have flown 8 million km (5 million miles) during its over-50 year lifespan.[33]
Some large broad-winged birds rely on thermal columns of rising hot air to enable them to soar. These include many birds of prey such as vultures, eagles, andbuzzards, but also storks. These birds migrate in the daytime. Migratory species in these groups have great difficulty crossing large bodies of water, since thermals only form over land, and these birds cannot maintain active flight for long distances. Mediterranean and other seas present a major obstacle to soaring birds, which must cross at the narrowest points. Massive numbers of large raptors and storks pass through areas such as Gibraltar, Falsterbo, and the Bosphorus at migration times. More common species, such as the European Honey Buzzard, can be counted in hundreds of thousands in autumn. Other barriers, such as mountain ranges, can also cause funnelling, particularly of large diurnal migrants. This is a notable factor in the Central American migratory bottleneck. Batumi bottleneck in the Caucasus is one of the heaviest migratory funnels on earth. Avoiding flying over the Black Sea surface and across high mountains, hundreds of thousands of soaring birds funnel through an area around the city of Batumi, Georgia.[34] It has been suggested [35] that birds of prey (such as Honey Buzzards) which migrate using thermals may benefit from losing 10 to 20% of their weight and that this may explain why they forage less on migration than do smaller birds of prey with more active flight such as Falcons, Hawks and Harriers.
Many of the smaller insectivorous birds including the warblers, hummingbirds andflycatchers migrate large distances, usually at night. They land in the morning and may feed for a few days before resuming their migration. The birds are referred to aspassage migrants in the regions where they occur for short durations between the origin and destination.[36]
Nocturnal migrants minimize predation, avoid overheating, and feed during the day.[20] One cost of nocturnal migration is the loss of sleep. Migrants may be able to alter their quality of sleep to compensate for the loss.[37]
Physiology and control[edit]
The control of migration, its timing and response are genetically controlled and appear to be a primitive trait that is present even in non-migratory species of birds. The ability to navigate and orient themselves during migration is a much more complex phenomenon that may include both endogenous programs as well as learning.[43]
Timing[edit]
The primary physiological cue for migration are the changes in the day length. These changes are also related to hormonal changes in the birds.
In the period before migration, many birds display higher activity or Zugunruhe (German: migratory restlessness) as well as physiological changes such as increased fat deposition. The occurrence of Zugunruhe even in cage-raised birds with no environmental cues (e.g. shortening of day and falling temperature) has pointed to the role of circannual endogenousprograms in controlling bird migrations. Caged birds display a preferential flight direction that corresponds with the migratory direction they would take in nature, even changing their preferential direction at roughly the same time their wild conspecifics change course.[citation needed]
In species where there is polygyny and with considerable sexual dimorphism, there is a tendency for males to return earlier to the breeding sites than their females. This is termed as protandry.[44][45]
[edit]
Main article: Animal navigation
Navigation is based on a variety of senses. Many birds have been shown to use a sun compass. Using the sun for direction involves the need for making compensation based on the time. Navigation has also been shown to be based on a combination of other abilities including the ability to detect magnetic fields (magnetoception), use visual landmarks as well as olfactory cues.[46]
Long distance migrants are believed to disperse as young birds and form attachments to potential breeding sites and to favourite wintering sites. Once the site attachment is made they show high site-fidelity, visiting the same wintering sites year after year.[47]
The ability of birds to navigate during migrations cannot be fully explained by endogenous programming, even with the help of responses to environmental cues. The ability to successfully perform long-distance migrations can probably only be fully explained with an accounting for the cognitive ability of the birds to recognize habitats and form mental maps. Satellite tracking of day migrating raptors such as Ospreys and Honey Buzzards has shown that older individuals are better at making corrections for wind drift.[48]
As the circannual patterns indicate, there is a strong genetic component to migration in terms of timing and route, but this may be modified by environmental influences. An interesting example where a change of migration route has occurred because of such a geographical barrier is the trend for some Blackcaps in central Europe to migrate west and winter inBritain rather than cross the Alps.[citation needed]
Migratory birds may use two electromagnetic tools to find their destinations: one that is entirely innate and another that relies on experience. A young bird on its first migration flies in the correct direction according to the Earth's magnetic field, but does not know how far the journey will be. It does this through a radical pair mechanism whereby chemical reactions in special photo pigments sensitive to long wavelengths are affected by the field. Although this only works during daylight hours, it does not use the position of the sun in any way. At this stage the bird is similar to a boy scout with a compass but no map, until it grows accustomed to the journey and can put its other facilities to use. With experience they learn various landmarks and this "mapping" is done by magnetites in the trigeminal system, which tell the bird how strong the field is. Because birds migrate between northern and southern regions, the magnetic field strengths at different latitudes let it interpret the radical pair mechanism more accurately and let it know when it has reached its destination.[49] More recent research has found a neural connection between the eye and "Cluster N", the part of the forebrain that is active during migrational orientation, suggesting that birds may actually be able to see the magnetic field of the earth.[50][51]
Vagrancy[edit]
Migrating birds can lose their way and appear outside their normal ranges. This can be due to flying past their destinations as in the "spring overshoot" in which birds returning to their breeding areas overshoot and end up further north than intended. Reverse migration, where the genetic programming of young birds fails to work properly, can lead to great rarities turning up as vagrants thousands of kilometres out of range. Certain areas, because of their location, have become famous as watchpoints for migrating birds. Examples are the Point Pelee National Park in Canada, and Spurn in England. Drift migration of birds blown off course by the wind can result in "falls" of large numbers of migrants at coastal sites.[citation needed]
A related phenomenon called "abmigration" involves birds from one region joining similar birds from a different breeding region in the common winter grounds and then migrating back along with the new population. This is especially common in some waterfowl, which shift from one flyway to another.[52]
Migration conditioning[edit]
It has been possible to teach a migration route to a flock of birds, for example in re-introduction schemes. After a trial withCanada Geese, microlight aircraft were used in the US to teach safe migration routes to reintroduced Whooping Cranes.[53][54]
Adaptations[edit]
Birds need to alter their metabolism in order to meet the demands of migration. The storage of energy through the accumulation of fat and the control of sleep in nocturnal migrants require special physiological adaptations. In addition, the feathers of a bird suffer from wear-and-tear and require to be molted. The timing of this molt - usually once a year but sometimes two - varies with some species molting prior to moving to their winter grounds and others molting prior to returning to their breeding grounds.[55][56] Apart from physiological adaptations, migration sometimes requires behavioural changes such as flying in flocks to reduce the energy used in migration or the risk of predation.[57]
Evolutionary and ecological factors[edit]
Migration in birds is highly labile and is believed to have developed independently in many avian lineages.[58] While it is agreed that the behavioral and physiological adaptations necessary for migration are under genetic control, some authors have argued that no genetic change is necessary for migratory behavior to develop in a sedentary species because the genetic framework for migratory behavior exists in nearly all avian lineages.[59] This explains the rapid appearance of migratory behavior after the most recent glacial maximum.[60]
Whether a particular species migrates depends on a number of factors. The climate of the breeding area is important, and few species can cope with the harsh winters of inland Canada or northern Eurasia. Thus the partially migratory BlackbirdTurdus merula is migratory in Scandinavia, but not in the milder climate of southern Europe. The nature of the staple food is also significant. Most specialist insect eaters outside the tropics are long-distance migrants, and have little choice but to head south in winter.[citation needed]
Sometimes the factors are finely balanced. The Whinchat Saxicola rubetra of Europe and the Siberian Stonechat Saxicola maura of Asia are long-distance migrants wintering in the tropics, whereas their close relative, the European StonechatSaxicola rubicola is a resident bird in most of its range, and moves only short distances from the colder north and east. A possible factor here is that the resident species can often raise an extra brood.[citation needed]
Recent research suggests that long-distance passerine migrants are of South American and African, rather than northern hemisphere, evolutionary origins. They are effectively southern species coming north to breed rather than northern species going south to winter.[citation needed]
Theoretical analyses, summarized by Alerstam (2001), show that detours that increase flight distance by up to 20% will often be adaptive on aerodynamic grounds - a bird that loads itself with food to cross a long barrier flies less efficiently. However some species show circuitous migratory routes that reflect historical range expansions and are far from optimal in ecological terms. An example is the migration of continental populations of Swainson's Thrush, which fly far east across North Americabefore turning south via Florida to reach northern South America; this route is believed to be the consequence of a range expansion that occurred about 10,000 years ago. Detours may also be caused by differential wind conditions, predation risk, or other factors.[citation needed]
Climate change[edit]
Large scale climatic changes, as have been experienced in the past, are expected to have an effect on the timing of migration. Studies have shown a variety of effects including timing changes in migration, breeding[61] as well as population variations.[62][63]
Ecological effects[edit]
The migration of birds also aids the movement of other species, including those of ectoparasites such as ticks and lice,[64]which in turn may carry micro-organisms including those of concern to human health. Considerable interest has been taken due to the global spread of avian influenza, however migrant birds have not been found to be a special risk, with import of pet and domestic birds being a greater threat.[65] Some viruses that are maintained in birds without lethal effects, such as the West Nile Virus may however be spread by migrating birds.[66] Birds may also have a role in the dispersal of propagules of plants and plankton.[67][68]
Some predators take advantage of the concentration of birds during migration. Greater Noctule bats feed on nocturnal migrating passerines.[7] Some birds of prey specialize on migrating waders.[69]
Threats and conservation[edit]
Main article: Bird migration perils
Human activities have threatened many migratory bird species. The distances involved in bird migration mean that they often cross political boundaries of countries and conservation measures require international cooperation. Several international treaties have been signed to protect migratory species including the Migratory Bird Treaty Act of 1918 of the US.[78] and theAfrican-Eurasian Migratory Waterbird Agreement[79]
The concentration of birds during migration can put species at risk. Some spectacular migrants have already gone extinct, the most notable being the Passenger Pigeon (Ectopistes migratorius). During migration the enormous flocks were a mile (1.6 km) wide, darkening the sky and 300 miles (480 km) long, taking several days to pass.[80]
Other significant areas include stop-over sites between the wintering and breeding territories.[81] A capture-recapture study of passerine migrants with high fidelity for breeding and wintering sites did not show similar strict association with stop-over sites.[82]
Hunting along the migratory route can also take a heavy toll. The populations of Siberian Cranes that wintered in Indiadeclined due to hunting along the route, particularly in Afghanistan and Central Asia. Birds were last seen in their favourite wintering grounds in Keoladeo National Park in 2002.[83]
Structures such as power lines, wind farms and offshore oil-rigs have also been known to affect migratory birds.[84] Habitat destruction by land use changes is the biggest threat, and shallow wetlands that are stopover and wintering sites for migratory birds are particularly threatened by draining and reclamation for human use.
...this is brendasue signing off from Rainbow Creek. See You next time!
Record Cold Coming Tomorrow to Texas!
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