external image pigeon.jpg



PigeonBy Leah Carlson

Classification/Diagnostic Characteristics
Kingdom: Animalia

Phylum: Chordata

Subphylum: Vertebrata

Class: Aves

Order: Columbiformes

Family: Columbidae
Pigeons range from about 12 to 33 inches, generally much larger than the dove that ranges from the 6 to 12 inches. Pigeons generally have round or square tails that has a fleshy growth at the base of the tail. The plumage, or birds feathers, are thick with metallic sections. The feathers appearance vary from a uniform brown of the temperate-zone species to bright/bold hues and patterns in tropical areas. Also, male and female species tend to look similar. (2) (PS)
  • 32-37 cm long
  • 64-72 cm wingspan
  • Dark bluish-grey head, neck and chest with glossy greenish and reddish-purple iridescence around the neck and wing feathers
  • Orange or red iris with pale inner ring (adult) or brown or greyish brown (juveniles)
  • Black bill with off-white cere
  • Red feet and legs
  • black bars on wings
  • White lower back feathers (8)(KG)



the-pigeon-diagram.jpg

A diagram illustrating the anatomy of a pigeon. (3) (E.S.S.)
Relationship to humansPigeons are known to live in large cities and many people feed them scraps of food.
fat pigeon.jpg
Figure 3. Rotund pigeons feed on human food, exemplifying the fattening effects of modern human diet[12] (AY)





Throughout history people have used the pigeons amazing homing abilities. Pigeons have a very good sense of direction, and because of this people have used them to carry messages. Rock Pigeons (the most common species in the United States) are originally from Europe and Asia, however, when the Europeans settled in America, they introduced them to the continent. These birds now use our buildings as nesting sites rather than cliffs that they utilized in Europe and Asia. (5) (WSS)
Mike Tyson got in his first fight defending his pet pigeons. (13) (ES)
Pigeons appear throught common mythology. In the Jewish Bible a dove (pigeon) was the first animal to sight land after the Great Flood. Jesus's parents offered doves after Jesus was circumcised. Thus the "peace dove" became a common symbol for the Holy Spirit. In Islam it is believed that pigeons assisted Muhammad by distracting his enemies. (17)(BS)
Habitat and NichePigeons live in northern cities and tend to live in flocks.
Pigeons live everywhere on the earth except for the driest areas of the Sahara Desert, Antarctica and its surrounding islands, and the most northern parts of the Arctic. The most number of species have inhabited tropical forests and woodlands. Other regions include savanna, grasslands, deserts, temperate woodlands, forests, mangrove forests, and even barren atolls. Pigeons have also inhabited the majority of the world's oceanic islands. (8) (BH)
Due to pigeons ability to distinguish areas and good sense of direction people used pigeons to send letter across the country. (HSC)
Predator Avoidance
Hawks are a known predator and pigeons tend to live in flocks to avoid attack. Living in large flocks allows the pigeons to warn each other faster than a smaller flock.


In addition to traveling in large packs, pigeons also use a common defense mechanism of birds known as the broken wing display that divert a predators attention away from a birds nest. Pigeons also have rather short nesting periods to avoid the chance that a predator can attack the nest [1] (CC)
Nutrient acquisitionPigeons acquire nutrients from fruits, insects, seeds, nectar, pollen, leaves, buds, as well as food from humans.
Pigeons, like most avian creatures have a gizzard that uses grit (small sharp stones) to grind up grain. When the stones become worn down and rounded they are eliminated via the droppings. Grit also contains calcium. The strongly acid stomach juices quickly make it available. This calcium can only be partly absorbed. (9) (MC)


Reproduction and Life CyclePigeons are amniotes; reproduction requires internal fertilization and they lay eggs.

When pigeons are young, they have little reproductive success, but they claim territory for future reproduction.

When the pigeons hatch, imprinting occurs. This allows the mother to teach the hatchlings the sound of her call as well as the mother recognizing the sound of her hatchlings.

Pigeons are monogamous, meaning they usually mate for life with the same partner. Female pigeons can reproduce starting at 7 months. 8 to 12 days after mating a female pigeon will lay 1 to 3 eggs that hatch in 18 days. New born chicks are sparse yellow or white down and fledge (leave the nest) in 25 to 32 days. [2] , (SM)
Pigeons breed all year round with but breed the most during the spring and summer. Pigeons will start to breed at about 6 months of age. (8)(KG)

Pigeons build nests from sticks and anything they can pick up which may be placed in trees, on ledges, or on the ground. They lay one or two eggs, and both parents care for the young, who leave the nest after 1 to 4 weeks. Unlike most birds, both sexes of pigeons produce "crop milk" to feed to their young, secreted by a collection of fluid-filled cells from the lining of the crop. Pigeon young are called "squabs". (Shwetha) (15)

Growth and Development


Once the cell starts to cleave, or split, it results in a flat, circular disc of cells called a blastodisc.

Cells that break off of the blastodisc form a layer called the hypoblast, which will support and nourish the developing pigeon embryo.

Pigeon Growth Day by Day (AWC)
The cells over the hypoblast form the epiblast, which will form the pigeon embryo.

First, the posterior of the epiblast thickens, which forms a midline ridge called the midline streak. Along the primitive streak, the primitive groove forms. This acts as the blastopore in which cells migrate through to the blastocoel. Cells are then determined between the endoderm and the mesoderm.

Then, the endoderm and mesoderm start to form the gut and other structures. The anterior of the primitive groove thickens, called Hensen’s node, which is like the dorsal lip of the amphibian blastopore.

Once the pigeon is fully formed, it then breaks the shell open and is taken care of by the mother.

After the pigeon becomes an adult, it can be hard to tell the difference between and a male and female pigeon, so there are four distinct characteristics between the sexes- size, color, sex organs, and behavior. The male pigeons tend to be huge and fatter than the female pigeons. Male pigeons also have bright orange rings around the iris while females light orange or green-gray rings. Also males testicles in pigeons are bigger in the mating season while females have one ovary that is attached to an oviduct. When mating season occurs, male pigeon make loud and slow noises while tipping to the ground and their tails unfasten into a shape of half of a circle while females admire their feathers. Male pigeons also poke at the females' heads with their beaks.(11)(NC)

IntegumentPigeons have a dry epidermis, or skin, which allows for minimum water loss.

They also have a layer of feathers, which are lightweight and structurally complex. These feathers allow the pigeon to fly and also provide insulation.
Many Scientists believe that the driving evolutionary force behind feathers was insulation and for protection against u.v light. Feathers evolved out of keratinous scales and pigeons still have those scales on their legs and feet. Feathers are made out of the protein keratin, common among many species for its use as an outer layer of skin, and are similar in composition to nails or hair. In many species of pigeon feathers are used as a determining factor in sexual section. (12) (DA)


Movement

Structure of the wing (10) (AA)
Structure of the wing (10) (AA)

The feathers allow the pigeon to fly. The tail feathers act as a stabilizer and the feathers on the wings allow flight.
The pigeon can fly because its bones are lightweight, it has strong wing muscles, and its wings are designed for flight. The hollow bones allows the pigeons skeleton to be extremely light and the strong wing muscles gives the pigeon enough power to propel itself through the air. Furthermore, the wing has evolved such that air moves at a greater velocity above the wing than below. Bernoulli's principle dictates that the faster moving air has lower pressure, so the higher pressure air below the wing forces the wing up, generating lift. This is allows the pigeon to use as little energy as possible to maintain vertical position. On the downstroke of the wing, it is fully extended, so the pigeon uses as much surface area as possible to push air downwards (thus forcing the pigeon upwards). However, on the upstroke, the wings are folded, minimizing the surface area used to push air upwards and therefore minimizing how much the pigeon moves downwards. [3] (FZ)



Slow-Motion Video of Pigeon in Flight at 300fps. (DM) (16)






Sensing the EnvironmentPigeons have a nervous system that allows them to sense the temperature of the environment. When the weather is colder, pigeons tend to move south for survival.
Gas ExchangeThe lungs within a pigeon do not change significantly in volume because the air moves unidirectionally, although there is a slight decrease in volume during inhalation and a slight increase in volume during exhalation.external image 533px-BirdRespiration.svg.pngDiagram of the pigeon respiratory system. (4)(BB-V)

The air enters the posterior of the lungs and flows through tubes called parabronchi. These branch into capillaries where gas exchange occurs between oxygen and carbon dioxide. The capillaries then form back into parabronchi, which then coalesce into larger bronchi to allow air to flow out the anterior of the lungs.

Waste RemovalPigeons remove toxic waste, such as ammonia, through uric acid.

Uric acid is not soluble in water therefore it is secreted as a semisolid (whitish paste). Uric acid also allows the pigeon to conserve water because it does not require a significant amount of water to remove from the body, this allows the excess water to be absorbed back into the pigeons body.

Environmental PhysiologyPigeons can survive very well without much water. They lay eggs, which allows them to reproduce without water and the eggs do not allow evaporation. They also have dry skin to minimize water loss and excreting uric acid allows them to conserve water.

Pigeons can also survive in cooler temperatures than other birds because of their thick coat of feathers.
Most Pigeons can be found in an urban or suburban area. They like to stand or rest on man-made buildings. Most often if you looked upon a building and saw a pigeon, you would see a lot of them because that is where they all congregate. (18)(ES)

Internal CirculationPigeons have a four-chambered heart to maximize the circulation of arterial, or oxygenated blood. The left atrium receives arterial blood from the pulmonary circuit (lungs) and it then flows into the left ventricle. The left ventricle then pumps the arterial blood through the systemic circuit, or the body.

The right atrium receives the venous blood, or deoxygenated blood, from the body. This pumps the venous blood into the right ventricle from which it is pumped back into the pulmonary circuit.

Separate pulmonary and systemic circuit allows for a high metabolic rate and direct blood flow for the pigeon to keep a steady body temperature.


birddigestive[1].gif (TM)


Chemical ControlThe hormone testosterone plays a part in the tone of the pigeons call which allows for easier imprinting.

The hypothalamus sets a body temperature rate for the birds to control their body temperature using metabolic heat; therefore they are considered to be endothermic.

The hormone prolactin stimulates nesting and parental care for female pigeons.


Review Questions1. A mother pigeon uses what technique to teach her hatchlings the sound of her call? (JLev)2. What aspect of a pigeon's heart allow the pigeon's organs to receive the most possible oxygen and to remove the most waste? (AA)3. Why do people always see pigeons in flocks? (JLau)


References
  1. ^ http://animaldiversity.ummz.umich.edu/accounts/Columbidae/
  2. ^ __https://ovocontrol.com/pigeons/pigeons/__
  3. ^ http://van.physics.illinois.edu/qa/listing.php?id=760

1. Hillis, David M. Principles of Life. Sunderland, MA: Sinauer Associates, 2012. Print
2. http://animals.howstuffworks.com/birds/pigeon-info1.htm
3.

http://www.google.com/imgres?q=pigeon+diagrams&um=1&hl=en&client=firefox-a&rls=org.mozilla:en-US:official&tbm=isch&tbnid=G0lCJ3BmBUktQM:&imgrefurl=http://thepigeon.co.nz/about/attachment/the-pigeon-diagram/&docid=BKLvo9o9B9c36M&imgurl=http://thepigeon.co.nz/wp-content/uploads/2010/11/the-pigeon-diagram.jpg&w=550&h=420&ei=y_vLUL7TMYnh0wHR0IDgDA&zoom=1&iact=hc&vpx=266&vpy=117&dur=4464&hovh=196&hovw=257&tx=153&ty=96&sig=102556723403260693261&page=1&tbnh=144&tbnw=189&start=0&ndsp=13&ved=1t:429,r:1,s:0,i:73&biw=958&bih=601
4. http://upload.wikimedia.org/wikipedia/commons/thumb/f/f2/BirdRespiration.svg/533px-BirdRespiration.svg.png
5. http://nationalzoo.si.edu/scbi/migratorybirds/featured_birds/default.cfm?bird=Rock_Pigeon
6. __https://ovocontrol.com/pigeons/pigeons/__

8. http://www.pigeoncontrolresourcecentre.org/html/about-pigeons.html
9. http://www.pigeonracingpigeon.com/menu/digestion-process-in-pigeons/
10. http://www.pigeonracingpigeon.com/wp-content/uploads/2011/05/wing-anatomy.jpg
11.http://www.ehow.com/info_8525438_difference-between-male-female-pigeons.html
12. http://www.earthlife.net/birds/feathers.html
13. http://www.mnn.com/lifestyle/arts-culture/blogs/mike-tysons-first-fight-was-over-birds
14. "Fat Pigeon Pie" <http://slice.seriouseats.com/archives/2011/11/photo-of-the-day-fat-pigeon-pie.html>
15. http://en.wikipedia.org/wiki/Columbidae16. http://www.youtube.com/watch?v=U8oLBGRxBeU17. Kovacs, Maureen Gallery (1989). The epic of Gilgamesh. Stanford University Press. p. 10218.http://web.extension.illinois.edu/wildlife/directory_show.cfm?species=pigeon