full transcript

From the Ted Talk by Gillian Gibb: Why can't some birds fly?

Unscramble the Blue Letters


When a bird species doesn’t face specific pressures to fly, it can stop flying in as quickly as a few generations. Then, over tsdohanus or millions of years, the birds’ bedois change to match this new behavior. Their boens, once hollow to minimize whgiet, become dense. Their sdurty fatheers turn to fluff. Their wings shrink, and in some cases disappear entirely. And the keel-like protrusion on their sternums, where the flight muscles aatcth, shrinks or disappears, except in penguins, who repurpose their flight melsucs and keels for siwimnmg.

Most often, flightlessness evolves after a bird species flies to an island where there are no predators. As long as these predator-free circumstances last, the brdis thrive, but they are vulnerable to changes in their environment. For instance, hamun serttels bring dogs, cats, and stowaway rodents to islands. These animals often prey on flightless birds and can drive them to eittincxon. In New Zealand, sttaos introduced by European settlers have threatened many native species of flightless bird. Some have gone extinct while others are endangered. So in spite of the energy-saving advantages of flightlessness, many flightless bird species have only a short run before going the way of the dodo.

Open Cloze


When a bird species doesn’t face specific pressures to fly, it can stop flying in as quickly as a few generations. Then, over _________ or millions of years, the birds’ ______ change to match this new behavior. Their _____, once hollow to minimize ______, become dense. Their ______ ________ turn to fluff. Their wings shrink, and in some cases disappear entirely. And the keel-like protrusion on their sternums, where the flight muscles ______, shrinks or disappears, except in penguins, who repurpose their flight _______ and keels for ________.

Most often, flightlessness evolves after a bird species flies to an island where there are no predators. As long as these predator-free circumstances last, the _____ thrive, but they are vulnerable to changes in their environment. For instance, _____ ________ bring dogs, cats, and stowaway rodents to islands. These animals often prey on flightless birds and can drive them to __________. In New Zealand, ______ introduced by European settlers have threatened many native species of flightless bird. Some have gone extinct while others are endangered. So in spite of the energy-saving advantages of flightlessness, many flightless bird species have only a short run before going the way of the dodo.

Solution


  1. stoats
  2. settlers
  3. thousands
  4. human
  5. sturdy
  6. swimming
  7. bones
  8. weight
  9. extinction
  10. muscles
  11. bodies
  12. feathers
  13. attach
  14. birds

Original Text


When a bird species doesn’t face specific pressures to fly, it can stop flying in as quickly as a few generations. Then, over thousands or millions of years, the birds’ bodies change to match this new behavior. Their bones, once hollow to minimize weight, become dense. Their sturdy feathers turn to fluff. Their wings shrink, and in some cases disappear entirely. And the keel-like protrusion on their sternums, where the flight muscles attach, shrinks or disappears, except in penguins, who repurpose their flight muscles and keels for swimming.

Most often, flightlessness evolves after a bird species flies to an island where there are no predators. As long as these predator-free circumstances last, the birds thrive, but they are vulnerable to changes in their environment. For instance, human settlers bring dogs, cats, and stowaway rodents to islands. These animals often prey on flightless birds and can drive them to extinction. In New Zealand, stoats introduced by European settlers have threatened many native species of flightless bird. Some have gone extinct while others are endangered. So in spite of the energy-saving advantages of flightlessness, many flightless bird species have only a short run before going the way of the dodo.

Frequently Occurring Word Combinations


ngrams of length 2

collocation frequency
bird species 4
flightless birds 3
flight muscles 2
flightless bird 2


Important Words


  1. advantages
  2. animals
  3. attach
  4. behavior
  5. bird
  6. birds
  7. bodies
  8. bones
  9. bring
  10. cases
  11. cats
  12. change
  13. circumstances
  14. dense
  15. disappear
  16. disappears
  17. dodo
  18. dogs
  19. drive
  20. endangered
  21. environment
  22. european
  23. evolves
  24. extinct
  25. extinction
  26. face
  27. feathers
  28. flies
  29. flight
  30. flightless
  31. flightlessness
  32. fluff
  33. fly
  34. flying
  35. generations
  36. hollow
  37. human
  38. instance
  39. introduced
  40. island
  41. islands
  42. keels
  43. long
  44. match
  45. millions
  46. minimize
  47. muscles
  48. native
  49. penguins
  50. predators
  51. pressures
  52. prey
  53. protrusion
  54. quickly
  55. repurpose
  56. rodents
  57. run
  58. settlers
  59. short
  60. shrink
  61. shrinks
  62. species
  63. specific
  64. spite
  65. sternums
  66. stoats
  67. stop
  68. stowaway
  69. sturdy
  70. swimming
  71. thousands
  72. threatened
  73. thrive
  74. turn
  75. vulnerable
  76. weight
  77. wings
  78. years
  79. zealand