What is Bird: Definition and 124 Discussions

Birds are a group of warm-blooded vertebrates constituting the class Aves , characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweight skeleton. Birds live worldwide and range in size from the 5.5 cm (2.2 in) bee hummingbird to the 2.8 m (9 ft 2 in) ostrich. There are about ten thousand living species, more than half of which are passerine, or "perching" birds. Birds have wings whose development varies according to species; the only known groups without wings are the extinct moa and elephant birds. Wings, which evolved from forelimbs, gave birds the ability to fly, although further evolution has led to the loss of flight in some birds, including ratites, penguins, and diverse endemic island species. The digestive and respiratory systems of birds are also uniquely adapted for flight. Some bird species of aquatic environments, particularly seabirds and some waterbirds, have further evolved for swimming.
Birds are a group of feathered theropod dinosaurs and constitute the only living dinosaurs. Likewise, birds are considered reptiles in the modern cladistic sense of the term, and their closest living relatives are the crocodilians. Birds are descendants of the primitive avialans (whose members include Archaeopteryx) which first appeared about 160 million years ago (mya) in China. According to DNA evidence, modern birds (Neornithes) evolved in the Middle to Late Cretaceous, and diversified dramatically around the time of the Cretaceous–Paleogene extinction event 66 mya, which killed off the pterosaurs and all non-avian dinosaurs.
Many social species pass on knowledge across generations, which is considered a form of culture. Birds are social, communicating with visual signals, calls, and songs, and participating in such behaviours as cooperative breeding and hunting, flocking, and mobbing of predators. The vast majority of bird species are socially (but not necessarily sexually) monogamous, usually for one breeding season at a time, sometimes for years, but rarely for life. Other species have breeding systems that are polygynous (one male with many females) or, rarely, polyandrous (one female with many males). Birds produce offspring by laying eggs which are fertilised through sexual reproduction. They are usually laid in a nest and incubated by the parents. Most birds have an extended period of parental care after hatching.
Many species of birds are economically important as food for human consumption and raw material in manufacturing, with domesticated and undomesticated birds being important sources of eggs, meat, and feathers. Songbirds, parrots, and other species are popular as pets. Guano (bird excrement) is harvested for use as a fertiliser. Birds figure throughout human culture. About 120 to 130 species have become extinct due to human activity since the 17th century, and hundreds more before then. Human activity threatens about 1,200 bird species with extinction, though efforts are underway to protect them. Recreational birdwatching is an important part of the ecotourism industry.

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  1. Emmanuel Pil

    B Why doesn't wind drag a hovering Kestrel bird backwards?

    I know it's all about drag and lift, but why doesn't the wind drag this bird backwards?
  2. DaveC426913

    What bird species laid these eggs in my garden?

    Found this clutch of eggs in my front garden today, not 2 yards from the sidewalk. Have never seen any large bird take an interest in garden. Count: 3 Colour: solid white, maybe a faint tinge of green, like the heron egg in this pic. No speckles. Matte finish. Size: 55mm long, 40mm in diameter*...
  3. J

    MHB Bird Flying Speed at 10m Altitude

    A bird is flying at an altitude of 10m above you, his angular position from your point of view is changing at 0.5 rad · s^-1. How fast is the bird flying when he is directly above you?
  4. iVenky

    When a bird flaps it's wings up, doesn't the pressure drop below?

    I am trying to understand how birds fly. If you consider a plane, using it's engine & streamline shape of the wings, it can create a low pressure region above the wings and high pressure region below and this makes it fly and the upward force is proportional to the speed. Birds seem to flap its...
  5. M

    Is This Bird Inspired by the Peregrine Falcon?

    What kind of bird is this? Anyone know?
  6. karush

    MHB 5.1.313 AP Calculus Exam DE on bird weight

    I just posted a image due to overleaf newcommands and graph ok (a) if we use f(20) then the $B=0$ so their no weight gain. (b), (c), was a little baffled and not sure how this graph was derived...
  7. E

    I Pressure vs Normal Stress: Exploring Bird Transport Phenomena

    What's really the difference between pressure and normal stress? Also I know pressure acts normal to a surface from the outside Do normal stress acts from inside? I'm reading bird transport phenomena and this is confusing
  8. Benjamin_harsh

    Is it possible to use the center of gravity to balance a bird toy?

    Here is the picture where person balancing a toy bird with using center of mass. I am bored with center of mass. I want to try same experiment with center of gravity. Is it possible to use center of gravity to balance bird toy ?
  9. D

    Why is a drinking bird colder than the ambient temperature?

    In a drinking bird, water from the wet on the outside of the head evaporates, causing the vapor inside the head of the bird to cool. This reduces the pressure of the vapor at the top, allowing the higher pressure in the lower bulb to push up the column of liquid. But the bird's body (including...
  10. C

    I need some clarification for a high school vectors question (accelerating bird)

    Homework Statement A bird flying in the air accelerates 2.82 m/s2 north for 4.11 seconds. the final velocity of the bird is 9.09 m/s [east]. What was the initial velocity of the bird? Homework Equations vf=v0+a*t v(average)=(v0+vf)/2 v=d/t d=v0t +½at2 tanθ=opp/adj The Attempt at a Solution...
  11. opus

    1-D Kinematics: Trains and a bird

    Homework Statement Two trains, each having a speed of 30km/h, are headed at each other on the same straight track. A bird that can fly 60 km/h flies off the front of one train when they are 60 km apart and heads directly for the other train. On reaching the other train, the bird flies directly...
  12. jim mcnamara

    Why Are People Risking Their Lives for the Bird Box Challenge?

    https://techcrunch.com/2019/01/02/netflix-pleads-with-people-to-stop-doing-the-bird-box-challenge/ People are driving with their eyes covered, wearing blindfolds for tasks that will get them hurt. Call it the Bird Box meme if you like. I prefer marginal insanity as a better label. Sounds like...
  13. Fabrizio Vassallo

    Weight of a box with a flying bird

    Hello! This is my first post here, and I look forward to many more! This is a sort of riddle I was told today, and left me full of doubts. So, the 'puzzle' was the following: " There's a man carrying behind his truck an enclosed trailer full of birds inside it. All the birds are standing on...
  14. Monoxdifly

    MHB [ASK] How much velocity is needed for the rock to be able to hit that bird?

    A bird is located at the (50, 8 ) m coordinate. A boy shot a rock at it using a slingshot with the elevation angle 37^{\circ}. How much velocity is needed for the rock to be able to hit that bird? I substituted all known variables (including the gravity acceleration 10m/s^2, with...
  15. J

    Relative velocity help -- A bird flying in a wind trying to get to its nest

    Homework Statement A bird can fly in still air at 100km/h. The wind blows at 90km/h from W(x degrees)S. The bird wishes to return to its nest which is due E of its present position. In which direction, relative to the air, should it fly?My textbook says that the velocity of the bird relative to...
  16. M

    MHB How many birds are at the top and bottom of the tree?

    Some birds are at the top of the tree while the others are at the botton, if one bird goes up, the birds of the top of the tree will be twice as the below of the tree while if one bird comes down the number of the birds at the top of the tree and below will be the same. How many birds are at...
  17. D

    Bird ID, please (seen at at the Sweetwater Wetlands in Tucson)

    Last week we saw this bird at the Sweetwater Wetlands in Tucson along the bank of a pond. The rigid upright position of the tail and the thickness at the base of the tail seemed to me to be the two most unusual features. Does anyone know what kind of bird it is? Thank you.
  18. A

    Quetzalcoatlus the 500 pound flying bird?

    Quetzalcoatlus is a prehisotric bird that can weigh up to 500 pounds. I am so shocked how a bird weighing up to 500 pounds can fly. How is this possible? Wouldn't the bird be to heavy to fly? Does the bird defy the laws of physics?
  19. jtbell

    Identify Mystery Bird in South Carolina

    I saw this while walking home today: I've seen it or one of its friends/relatives occasionally in the same area, over the years. It has a broad wingspan when flying. Unfortunately I wasn't quick enough to get a picture while it was in the air, and I couldn't get very close to it. This is in...
  20. I

    What forces act on a bird sitting on a sagging wire?

    Homework Statement 0.5 kg bird lands on wire of telephone poles that are 50m apart. The wire sags 0.15m. What's the tension in the wire? Ignore weight of the wire Homework EquationsThe Attempt at a Solution I figured out the angle that would be created (0.34 degrees) when the bird lands and...
  21. DaveC426913

    Preventing bird strikes on screens

    I am installing screening around my roofed deck. This is special stuff that's virtually invisible. My deck is well-shaded among dense trees, so that makes it even harder to see the screening. Birds visit my yard all the time, partly because of the foliage, and partly because I have a pond with...
  22. Evo

    99 Million-Year-Old Baby Bird Trapped in Amber

    99 Million-Year-Old Baby Bird Trapped in Amber Discovered in Myanmar https://www.yahoo.com/news/m/53c2c567-c77f-3c0d-a792-fccda32cdcc8/a-99-million-year-old-baby.html
  23. M

    MHB Probability of Turning into a Bird

    Substitute teacher, Baraba Rose, convinced a class of kindergarden kids that she would turn into a bird before the school day ends. What is the probability that this event will take place? Solution: Let P = probability P(turning into bird) = 0 The answer is 0 because human beings cannot turn...
  24. Dr_Jekyll

    I Trying to understand the drinking bird toy better

    I bought the drinking bird toy, and I want to get a better understanding of it, (https://en.wikipedia.org/wiki/Drinking_bird) I understand the basic way it works and that it is a simple heat engine, but I can't seem to find any information that helps me answer the following - I notice all...
  25. H

    Classical BSL Transport Phenom. vs. BSLK Introductory Transport Phenom

    I'd like to purchase one of these books for self-study. The BSLK Introductory Transport Phenomena claims: "Devoting more space to mathematical derivations and providing fuller explanations of mathematical developments—including a section of the appendix devoted to mathematical topics—allows...
  26. F

    I Can the bird return home?(about probability)

    Here's a question makes me confused. A bird leaves its home to find some food. It won't return if it doesn't find any food. Suppose the probability it returns in the first day is 1/2 and returns in the second day is 1/4 and returns in the third day is 1/8 ... returns in the nth day is (1/2)^n...
  27. M

    How to calculate the foraging radius of a bird?

    I would love someone to verify the answer for equation 8 in this paper (bottom of page 263) http://onlinelibrary.wiley.com/doi/10.1046/j.1365-2028.2002.00368.x/epdf For the sake of clarity here is the equation is LaTeX which you can render at the following link \frac{QC + Q\lambda \sigma -...
  28. Junjou

    What angle should the bird head?

    Homework Statement Canada geese migrate essentially along a north-south direction for well over a thousand kilometers in some cases, traveling at speeds up to about 100 km/h. The one goose is flying at 100 km/h relative to the air but a 34 km/h wind is blowing from west to east. At what angle...
  29. RJLiberator

    Conservation of Angular Momentum of a bird

    Homework Statement A bird m_b=0.470kg, is flying horizontally at v_b=2.50 m/s, not paying much attention, when it suddenly flies into a stationary vertical rod, hitting it d=25cm below the top. The rod is uniform, L=0.740m long, has a mass of m_r =1.60kg and is hinged at its base. This time the...
  30. L

    Rescuing Baby Bird: Advice Needed

    I found this baby bird in the parking lot with no trees above it. I have no idea how it got there. So I brought it inside and I don't know what to do. It keeps opening its mouth. What can I feed it? Is there any realistic chance this thing will survive? Thanks.
  31. S

    Distance and time of an Angry bird

    Homework Statement An angry bird of mass 2m is launched at theta = 45 degrees with initial velocity = 10 m/s above the horizontal. It then drops an egg of mass m= 1 kg vertically down with velocity 5sqrt(2) m/s when it is at the topmost point in its trajectory. (Bird's mass after egg drop is...
  32. Evo

    Have You Heard of a Half-Male, Half-Female Bird?

    I was not aware of such a thing. http://www.huffingtonpost.com/2014/12/30/half-male-half-female-bird-cardinal-plumage_n_6392336.html?utm_hp_ref=birds
  33. E

    BBC Jim Al-Khalili Presentation -- robin bird eyes use quantum entanglement?

    http://www.bbc.co.uk/programmes/b04v85cj I searched in this forum and no one has mentioned this. What are the thoughts of general physicists regarding Al-khalili presentation how the robin bird eyes use quantum entanglement? Searching at the net producing the following...
  34. B

    Simple continuous back-and-forth linear movement

    I need to purchase a device that will push something forward and backward continuously, in order to make wings flap like a bird. Linear actuators seem to be the right thing to buy, except these require pressing buttons to go forward and then back. What can I buy/what can I do that will allow a...
  35. H

    Why can a bird survive on a high voltage power line without getting fried?

    Homework Statement Birds can be seen perched on a high voltage power line yet seem unaffected by the high voltage. This is due to... A) Low resistance of the birds compared to the wire, minimizing current through the birds B) birds keeping only one foot on the wire, thus not completing a...
  36. I

    How to Calculate the Motion of a Dropped Fish in a Projectile Problem

    Homework Statement A sea bird catches a fish and then flies in an easterly direction with a speed v=7.39 m/s, h = 4.69 m above the surface of the sea. The fish has a mass of 115.3 g and is still alive. It thrashes and wiggles and as a result the bird drops the fish. i) What is the speed...
  37. M

    Is still there a bird group classified as Palmipedes?

    Hi, Is still there a bird group classified as Palmipedes? I can not find enough information in the internet for it and this is also the first entry in this science forum. Best Regards.
  38. lisab

    Identifying a Bird in Western Washington: Unusual Behavior.

    We used to have a bird thread here a long time ago, but it went dormant - maybe it's time for a new one? I need help identifying a bird. It's thrush-sized (~15 cm), nondescript brown-grey. I noticed it had unusual behavior: It perches on a branch, then flies out about a meter, does a...
  39. S

    Bird eyes - and how to model them

    OK so I am not sure if this should be on a physics forum, a maths forum or a biology forum. All I know is I am stuck. A little back ground: Researchers have modeled how various animals can see depending on their visual sensor cells, namely cones (colours vision) and rods (luminance)...
  40. D

    Jet-engine Bird Strike Protection

    Every time I see news of a bird killing a jet engine I immediately wonder why some sort of screen cannot be placed over its inlet to either catch the bird or at least dice it into small pieces. Why is this not possible?
  41. T

    When a bird flies into a bar; solving for angular velocity

    Homework Statement A 550.0g bird is flying horizontally at 2.20m/s , not paying much attention, when it suddenly flies into a stationary vertical bar, hitting it 25.0cm below the top. The bar is uniform, 0.730m long, has a mass of 2.20kg , and is hinged at its base. The collision stuns the...
  42. P

    What is the velocity of a flying bird on a windy day?

    A bird is flying through the air with an airspeed of 12.6m/s heading 27.7*west of north. it is a windy day with the wind blowing at 8.95m/s heading 12.5* south of west. what is the velocity of the bird as seen by the person on the ground
  43. 7

    How Do Birds Generate Lift and Drag While Gliding?

    1. A bird is gliding at an angle of 15° to the horizontal at a constant velocity. If the mass of the bird is 0.45 kg, calculate the lift and drag forces acting on the bird. 2.A bird is gliding with a constant velocity. Its forward speed is 5 m/s and its sinking speed is 0.88 m/s. If the...
  44. D

    What times is the bird flying horizontally/vertically?

    The flight of a bird follows the curve x=t-cos(t), y=3-2sin(t)... where 0<=t<=4pi is the time in seconds. a) What times is the bird flying horizontally? find the (x,y) coordinates of the corresponding points. b) What times is the bird flying vertically? find the (x,y) coordinates of the...
  45. P

    FBD representing a bird feeder.

    Homework Statement A bird sits in a birdfeeder suspended from a tree by a wire, as shown in the diagram below. Let WB and WF be the weight of the bird and the feeder respectively. Let T be the tension in the wire and N be the normal force between the bird and the feeder. Which of the...
  46. F

    Bird on an overhead line - Current flow

    Hi I have a basic question. When birds sit on an overhead line, they are sitting on a bare conductor which is transmitting high power, but they don't get electrocuted. I think the answer is because the bird itself doesn't complete the circuit so current won't flow through them, but I don't fully...
  47. Astronuc

    Transport Phenomena by Bird, Stewart, Lightfoot

    Author: R. Byron Bird, Warren E. Stewart, Edwin N. Lightfoot Title: Transport Phenomena, Revised 2nd Edition [Hardcover] Amazon Link: https://www.amazon.com/dp/0470115394/?tag=pfamazon01-20 Prerequisities: Advanced Calculus, Differential Equations (ODE, PDE), Introductory Heat Transfer...
  48. C

    Flight of Bird, Cubic Function

    Homework Statement A bird dove under water and re-emerged with a fish. Following is the table which shows the bird's estimated flight: Time(s),Height(m) 0, 7 2, 10 4, 5 6, 0 7, 0 8, 3 Find a cubic equation to model the data. 2. The...