Bird Adaptations

Question 1

Beak anatomy

Answer 1

• toothlessness a recent adaption = more lightweight
• bone beak with keratin sheath = aids ripping/piercing flesh
• bone integral to skull
• re-evolution of teeth-like structures appearing to hold fish

Question 2

Finches beak adaption

Answer 2

Crossed mandibles

Twists apart pine cones to get seeds

Question 3

Which species has longest bill relative to body

Answer 3

Sword-billed hummingbird

Can access nectar/pollen that other birds cant

Question 4

Relationship between prey and beak length

Answer 4

Long beak = locating prey by touch

Short bill= locating prey by sight

Question 5

E,g, of convergent evolution in bills

Answer 5

Spoonbill birds sieve sand in search of prey = flattened end of bill
Also found in ducks

Question 6

Describe kiwi bill adaptations

Answer 6

• Ground dwelling..eat invertebrates e,g, worms
• detect prey via touch and smell
• nostrils just back from edge so not clogged
• tip has sensory pits with clusters of touch receptors = Grandry and Herbst corpuscles

Question 7

E.g. tools used by birds

Answer 7

Some species have learnt to use tools out of body

E.g. woodpecker finches (Galapagos) and New Caledonian crow: sticks poked in holes to retrieve insects

Question 8

bird voice anatomy

Answer 8

Membranes that vibrate at diff frequencies when air drawn across
Bronchus splits in 2 with 2 membranes = 2 voices
- separate air flow and innervation

Question 9

Visualising bird song

Answer 9

On a sonogram
2 dimensional plot
Wide = harsh
Thin = pure

Question 10

Bill casque

Answer 10

Hollow chamber above bill
creates echoes of call so louder and diff frequency
E.g. rhinoceros hornbill

Question 11

Other methods of birds modifying sound

Answer 11

• snipe makes bleating sounds by dividing through air which rushes past stiff tail feathers
• Woodpeckers drum on hollow trunk = acts as resonating chamber
• Cockapoos make booming sound by facing bowl shaped depression in ground that amplifies sound
• barn owl clicks and hisses

Question 12

Correlated evolution of bill morphology and sing structure in Darwin’s finches

Answer 12

Sound involved in mate selection = reinforces natural selection 
- large birds make different sound to small, preventing mating 
Larger bill:
- low rate syllable repetition 
- narrow waveband 
Smaller bill:
- high rate syllable repetition
- wide waveband

Question 13

Character displacement

Answer 13

Anatomical changes resulting from a selective environment

Question 14

E.g. character displacement

Answer 14

Grant, Grant and Schulter
Daphne Major island
- Originally just small finches with medium beaks
- Large finches with medium beaks arrived
When both present small had small beaks, large had large beaks
- Due to competition
- increased when there was a drought as more intense competition

Question 15

Gene expression changes in finches under selection

Answer 15

• gene expression patterns during embryonic development of bill examined
• differences in cartilage and bone growth
• drives changes in depth, width and length of bill

Question 16

What can be derived when mapping diet onto finch phylogeny

Answer 16

Last common ancestor probably an insect eater
Ancestral species from S. America probably ate seed
Seed eating re-evolved more than once = evolutionary oscillation