BIRD BEHAVIOR, SONGS, SOUNDS, FLOCKING AND MIGRATING

BIRD BEHAVIOR

Birds preen, bathe and go through a lot of efforts to stay clean. They will even try to keep their feet from getting dirty. When no water is available they take dust bathes or expose themselves to sunlight. All birds bathe and usually follow their bathes with drying, shaking or scratching, feather-smoothing and using their bill to massage oil from a preening gland into their roughed up feathers. Cleaning and preening are necessary to keep plumage healthy

Many birds sleep at night. When they are sleeping, half of a bird's brain sleeps while half remains alert. This might explain why many birds sleep with one eye open. Some birds can sleep while flying. Some protect themselves from snakes by fluffing up their feathers so that a striking snake would only get a mouthful of feathers.

It is believed that some birds hang out in flocks because members of the group can alert others if there is predator or other danger in the area. They also flock for social reasons. Website: flock patterns: www.red3d.com/cwr/boids/

The Austrian naturalist Konrad Lorenz was the first person to describe how the young of some species of birds have a psychological mechanism in their brains that impels them to follow the first large moving object they see after the hatch from their eggs. Lorenz called the process "imprinting." Imprinting has been observed in geese, rails, coots and most famously with ducks. With the mallard ducking the process is very precise: taking place between 13 and 16 hours after the ducking hatches. In almost all cases the first large objects the young see is their mother but Lorenz shoed that birds deprived of their mother would follow him.

Research has shown that 30 percent of the flying birds is done for fun.

Websites and Resources: ; Essays on Various Topics Related to Birds stanford.edu/group/stanfordbird ; Avibase avibase.bsc-eoc.org ; Avian Web avianweb.com/birdspecies ; Bird Species Birdlife.org birdlife.org ; Bird.com birds.com Wikipedia article on Birds Wikipedia ; Birdlife International birdlife.org ; National Audubon Society birds.audubon.org ; Cornell Lab of Ornithology birds.cornell.edu ; Ornithology ornithology.com ; Internet Bird Collection (videos and recordings of bird species) ibc.lynxeds.com ; International Field Guides /media.library.uiuc.edu ;

Websites and Resources on Animals: ARKive arkive.org Animal Info animalinfo.org ; Animal Picture Archives (do a Search for the Animal Species You Want) animalpicturesarchive ; BBC Animals Finder bbc.co.uk/nature/animals ; Animal Diversity Web animaldiversity.ummz.umich.edu ; International Field Guides media.library.uiuc.edu ; animals.com animals.com/tags/animals-z ; Encyclopedia of Life eol.org ; World Wildlife Fund (WWF) worldwildlife.org ; National Geographic National Geographic ; Animal Planet animal.discovery.com ; Wikipedia article on Animals Wikipedia ; Animals.com animals.com ; Endangered Animals iucnredlist.org ; Endangered Species Resource List ucblibraries.colorado.edu ; Biodiversity Heritage Library biodiversitylibrary.org

Bird Sounds

Birds produce vocal sounds in a similar way to humans except they use a syrinx, a box-shaped organ surrounded by rings of cartilage, rather than a larynx. Running between the syrinx and the lungs are tubes. Noises and songs are produced by fleshy lip that control the air flow into the syrinx and vibrating muscles within the syrinx that control pitch and note quality.

Birds have a larynx but it does not produce sound. It prevents food and water from entering its windpipe and lungs. The bird larynx is located at the base of the windpipe (trachea) as opposed to the top where mammals make their sounds.

To make sounds birds push air out of their lungs through the syringeal muscles, which the bird can squeeze almost shut until they vibrate like a trumpeter's lips. These vibrations produce sound waves that travel from the base of the birds windpipe to its mouth. Bigger birds generally have bigger tracheas and a deeper timbre to their voices.

Young birds often go through a babbling stage similar to of human infants as they learn to make notes and produce songs. Their brains are wired so that they learn songs of their species and ignore other songs the same way babies learn to speak by listening to people and shutting out noises from cars and dishwashers.

Bird Songs

Bird produce a variety of sounds for a variety of reasons. Most are believed to be associated with courtship, defining territory, sounding alarms, calling other birds, and distinguishing friendly neighbors form potentially hostile strangers. Some species have difficulty identifying their own kind by sight but can easily identify them by their song. In temperate areas the best time to hear birds is in the spring and summer during the morning.

Studies indicate that birds don’t just make random trills and noises but produce what can arguably be called music. They often make the same acoustic and aesthetic choices and abide by the same rules of composition that human musicians and composers do. Birds use notes, rhythmic variations, harmonic patterns and pitch relationships found in human music and musical phrases of a similar length. Some thrushes sing in the so-called pentatonic scale, in which octaves are divided into five notes, which is the basis of music, including rock n' roll, found in many human cultures.

Males songbird often sing to let other males know that a particular territory belongs to them. Their courting songs are among the most complex songs. Many of these have traditionally been thought to be linked to the male demonstrating his ability to the female to provide food and fight predators but songs themselves have no link to any such purpose. Studies show that bird with the most complex songs often get the girl but as soon as they get the girl the singing stops. Among many species, though, females need a song cue from their mate to begin producing eggs and building a nest.

The number os songs that a particular species can sing varies quite a bit. A woodpecker may sing just three songs; a thrush, 50. A thrasher can sing more tan 2,000. In at least 200 species of birds, males and females sing "tightly-scripted duets throughout their relationship.” As a rule the bird with the most beautiful and sophisticated songs are unremarkable looking while the bird with most beautiful feathers and displays have the most unremarkable songs.

Book: Why Birds Sing by David Rothenberg (Basic Books, 2006)

Bird Babbling and Communication

Research by a team at MIT lead by Michael Fee published in the May 2008 edition of Science found that baby zebra fiches “babble” before they learn to sing their adult songs. “Birds start out babbling, just as humans do,” Fee told AP, while the adult bird produces a very precise pattern. With the finches the babbling took place during a 30 to 35 day period. The study also found that different parts of the brain controlled babbling and singing. Scientists were excited about the findings in that it offered insights into how language develops in humans and other animals.

Scientists have long wondered whether duets were the result of a pair birds singing together or an effort by two birds to avoid interfering with one another. A study of dueting Peruvian antbirds published in Current Biology by Joseph A. Tobias and Bathalue Seddon of Oxford University suggests it may be little of both with a pair singing together most of the time but the female occasionally attempting to jam the male’s song by singing over it. The findings were made by exposing antbird pairs to recorded songs of other antbirds and monitoring how they responded. When a tape of an intruding pair was played both the male and female cooperated to send out a message to stay away but when the song of a single female was splayed the male flirted while the female tried to drown out his song.

Bird Sex

About 90 percent of bird species are monogamous. Many times the male defends a territory with a sufficient food supply for his mate and their young. Male birds often have more flashy plumage than females. This may be at least partly because females need camouflage when they are nesting.

Birds copulate very quickly. Some species even copulate while they in the air. And male birds don't have a penis. Scientists speculate the reason for this may be a penis would weigh to much or interfere with standing or flying or engaging in a lengthy copulation would make the vulnerable to attacks for predators.

Both males and females posses a single rear vent called cloaca, which is connected to their sexual organs and their digestive tracts. During sex, both the male and female turn their cloacae inside out and place them end to end. Sperm from the male's sperms sacs travel through a duct and is transferred within seconds to the female's oviducts. It usually take some time for the sperm to travel up the oviduct and unite with the an egg. The sperm may remain alive in oviduct for days, even weeks.

David Attenborough wrote: "The actual mechanics of mating used by birds is clumsy. The male...has to mount rather precariously on the female's back, steadying himself by clinging onto her head feathers with his beak. She twists her tail to one side so that the two vents are brought together and the sperm, with a certain amount of muscle assistance from both partners is transferred to the female....The female has to remain very still or he topples off."

About 90 percent of bird species form pair bonds to breed. But some are not always faithful and will even pay for sex. Male great gray shrikes---elegant raptor-like birds with silver capes, white bellies and black tails---usually presents his mate with rodents, lizards, small birds and large insects that may be impaled on a stick. When seeking extra-marital sex he will offer a bigger kebab with even more goodies. Shrikes are also known for issuing alarm calls to warn one another of predators but also for issuing false alarms to drive other shrikes away.

Eggs

All birds lay eggs, a trait they inherited from reptiles. Bird are only vertebrates that exclusively lay eggs. Some species of other egg laying creatures such as reptiles and fish give birth to live young. Mammals give birth to live young partly because many mammal young need to move around to some degree to escape from predators soon after they are born.

Caring for eggs and young birds in many ways is more demanding and requires more attention than caring for live young. One of the main reasons that birds lay eggs is that carrying young around inside their body adversely affects the ability of the mother to fly. If the young can be removed from the body as quickly as possible in the form of an egg then the mother can continue flying even if she has had half a dozen young.

As an ovum passes down the duct leading from the female's ovary it is joined by a bag of yolk that provides nearly all the food needs for the developing embryo and chick. The ovum is then fertilized by a single sperm. Water and other nutrients are provided by the albumen which is wrapped around the yoke.

The ovum yolk and albumen mass then moves down passage called the ovidcye until they reach a section with a lime-secreting gland, which produces the shell. Further down are other glands which may decorate the shells with specks of pigment. The eggs is then pushed further and expelled.

Once embryos begin developing in their eggs they need to be kept warm. Otherwise they will die. Most often their mothers, and sometimes their fathers, keep them warm by sitting on them in the nest. Many birds have brood patches---areas denuded of feathers and rich in blood vessels used to warm the eggs. The incubation period can be anywhere from 10 to 80 days. usually small birds ahem shorter incubation period.

Young Birds

Bird eggs contain copious amounts of yoke so that the hatchlings emerge relatively large and strong and can quickly reach a size in which they are less vulnerable attacks from predators. An egg shell is not thicker than it is because the chick ultimately has to break out of it and the shell must be porous so that oxygen can reach the embryo.

Most chicks have an egg tooth---a tiny white spike usually on the upper mandible---and a special muscle on the back of their necks---which give strength to pull their heads backward an deliver pecks that are for strong enough to break the shell.

Some birds emerge helpless and need considerable attention for some weeks after they are born. Others like ducklings emerge relatively ready to take care of themselves.

Baby bird usually require between one half to their full body weight in food every day. Many parent birds regurgitate food to their young.

Flocking Birds

A flock that moves as a group in one direction can form as birds begin to orient themselves more strongly with other birds in the group.

Flocks of birds are effective at maintaining the well being of the flock. A flocking group is able to monitor a large area; gather information of what is there; relay the information to others and respond collectively to dangers and opportunities.

To examine the flocking behavior of birds, Craig Reynolds, a computer graphics researcher, created a seemingly simple steering program in 1986 called boids that helps demonstrate how flocking works. In the program generic birdlike objects, or boids, follow three simple rules: 1) avoid crowding nearby boids; 2) fly in the general direction of nearby boids, and 3) stay close to nearby boids. The result: convincing simulations of flocking behavior, including lifelike and unpredictable movements. The concept has been used to simulate swarming behavior in Hollywood movies, Sony video games and groups of small robots.

Studies by Iain Cousin at Oxford University found that a large group’say a flock of migrating birds---can head to a desired direction with only a couple of individuals knowing the way and each member of the group having two instincts; 1) staying with the group; and 2) moving in a desired direction. Two leaders may try to pull the flock in different direction but the flock tends to stay together.

Couzin told the New York Times, “As we increased the difference of opinion between the informed individuals, the groups would spontaneously come to a consensus and move in the direction chosen by the majority. They can make these decisions without mathematics or even recognizing each other or knowing that decision has been made.”

Migrating Birds

Every year billions of bird migrate between summering areas, where they nest and breed, and wintering areas where they feed and escape the escape the cold. The travel to the wintering areas in the autumn, navigating through fog, night skies and sometimes long expanses of ocean and desert and return in the spring. When choosing their time to migrate, birds seem to respond to cues such as lengthening or shortening amounts of daylight. The birds that arrive first often get their pick of the best feeding and nesting areas.

Some birds migrate several thousand miles. The fly over deserts, tundra and mountain ranges and rely on wetlands along the way to rest and replenish themselves. Often they will take a more circuitous route over land than a more direct route over the sea to gain access to wetlands and feeding spots.

Every year tens of thousands of migrating birds are killed when they fly into buildings. Many are attracted by light or of fly into windows after seeing reflections of things such as trees. In New York City and Chicago more than 32,000 birds from 147 species have died this way.

Species of songbirds may divide into new species when different subopulations decide to take different migration routes. European backcaps, for example, are divided into two major subpopulations, each with its own migratory pattern. Members of the subpopopualtes tend to only mate with their own kind. Over time they could develop into new species.

The migration patterns of some birds already seems to be disrupted by global warming. Populations of pied flycatchers, for example, a bird that nests in Europe and winters in Africa, are shrinking because caterpillars that parents traditionally fed to their young are appearing earlier because of warming temperatures and past their peak in numbers when the flycatchers fed them to their young. Fewer young birds are surviving because they don’t get enough to eat.

Studying Migrating Birds

Surprising little is known about the migrating habits of birds. Many patterns are thought to have evolved in the last 10,000 years because many places where birds spend the summer were under ice before that.

Scientist attempt to study migrating habits of birds by banding them. If someone finds a bird they are supposed to notify the contact imprinted on the band. A bird found in Ireland, for example, may have been banded and have a contact in Austria. The recovery rate of these bands is very poor. Of 450,000 pied flycatchers banded in their summering areas in Europe during a 60 year period fewer than five were recaptured in their wintering area.

Transmitters that send signals to satellites are too large for most birds. Tags placed on large sea birds, however, have recorded levels of ambient lights that can be translated into longitude and latitude and picked up by satellites. Sometimes birds are captured and kept in enclosures with ink on their feet. The direction the birds migrate is gauged by checking direction the birds want to fly based on the ink marks they leave behind.

Some scientists study whether birds winter or nest in southern or northern latitudes based on the amount of deuterium (the “heavy hydrogen” isotope) in their bodies. Deuterium is more prevalent on water supplies in northen latitudes. Migrations of large numbers of birds can be tracked with radar and satellites.

Using very small geolocaters, which weigh as little as paper clips and can be attached to even small birds, scientists have been able to track the migration of songbirds such as wood thrushes and purple martins for the first time. The scientist were surprised to find out how far the birds could fly. Some species traveled 480 kilometers a day, much further and faster than the 145 kilometers that had previously been estimated. Some purple martins that spend the winters in the Amazon, left Brazil in mid April and were back in North United States by the end of the month. Scientists had previously thought they must have left at least as early as March. The research was carried out by a team lead by Bridget Stutchbury, a professor of biology at the York University in Toronto.

The geolocators are small plastic devises that weigh 1.5 grams and record sunrise and sunset. They are placed in small backpacks that are fitted on the birds. When the birds are recaptured the times of the sunrises and sunset gives the location of the bird at each recording. In 2007 the devices were placed in 14 wood thrushes and 20 purples martins. In 2008 the geolocaters were retrieved on five wood thrushes and two purple martins. The wood thrushes wintered in Nicaragua and Honduras. The purple martins wintered in the Amazon, During the migration the birds rested for a few days in the southern United States and Mexico’s Yucatan area.

Endangered Birds and the Illegal Bird Trade

According to the official Red List by the World Conservation Union one in eight bird species is threatened. By some estimates at least on in ten bird species is likely to die out by the end of the 21st century, with another 15 percent hoovering on the brink of extinction. There are already some species that are raised in captivity but extinct in the wild..

In the last 500 years 135 species of bird have become extinct in the last 500 years, including, 8 in the 16th century, 11 in the 17th century, 26 in the 18th century, 49 in the 19th century and 43 in the 20th century.

Species have been lost due to poaching, habitat loss and overdevelopment. In the last three decades 21 species have been lost, including the Spixs macaw and the Hawaiian honeycreeper. Among the species that been saved through conservation efforts are the Bengal Florican in Cambodia, the Belding’s Yellowthroat in Mexico and the Restinga Antwren from Brazil.

Pet store birds generally have not had a very pleasant past. Some have been caught in the wild and subject to cramped cages and uncomfortable transportation. Many birds have been bred under stressful conditions.

In 2005, 1.5 million exotic birds as pets, 90 percent of the world’s total, were imported by Europe. In 2006, a ban that was put in place in Europe to halt the spread of bird flu also shut down the exotic bird trade, which was issued for all wild-caught birds.

Bird Conservation

Scientist say progress has been helping some of the most endangered bird species. A total of 31 birds including the California condor and Mauritius parakeet are said to have probably become extinct if it wasn’t for human intervention. Among the measures tat have helped birds are preserving their habitats, breeding and moving birds and controlling cats.

Britain-based Birdlife International launched an ambitious plan in 2007 to raise millions of dollars to help protect 189 endangered species of bird on the brink of extinction. The efforts is aimed at protecting habitats, raising awareness and reducing invasive species that often eat bird eggs and compete for food.

Birds and Global Warming

See Global Warming

According to research by a team lead by Victor Devictor, a researcher at the French National Museum of Natural History found that the habitats of wild bird species are shifting in response to global warming but not fast enough to stay ahead do rising temperatures. The study found that the geographic range of 105 bird species in France---accounted for 99.5 percent of the country’s wild birds---had shifted an average of 91 kilometers north between 1989 and 2006. The evidence was based on observations of birds by ornithologists and amateur birders at different times in 1,500 well-defined plots starting in 1989.

There have a number of observations of individual species shifting northward. What was particularly startling about the French study was that virtually all the bird species studied moved northward, “The response is faster than we thought but it is still not fast enough to keep up with climate change.”

Perhaps the worst consequence of global change for birds is that timing of their birds and their insect prey is getting out of sync. “The flora and fauna around us are shifting over time due to climate change,” Devictor told AFP. The result is desynchronisation. If birds and the insects upon which they depends do not react in the same way, we are headed for an upheaval in the interaction between species.”

A study by Stephen Willis of Durham University in Britain found that global warming is causing migrating birds to migrate further as their breeding grounds shift northward. His team that found that some types of warblers have to add 400 kilometers onto a already exhausting trips up to 6,000 kilometers to and from Africa. “For some bird the extra distance might make the difference between being able it make it or not. The study was published April 2009 in the Journal of Biogeography.

Image Sources: 1) 2) 3) 4) 5) 6) 7) 8)

Text Sources: Mostly National Geographic articles. Also Life on Earth by David Attenborough (Princeton University Press), New York Times, Washington Post, Los Angeles Times, Smithsonian magazine, Natural History magazine, Discover magazine, Times of London, The New Yorker, Time, Newsweek, Reuters, AP, AFP, Lonely Planet Guides, Compton’s Encyclopedia and various books and other publications.

Last updated March 2011

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