Birds Flashcards
What types of feathers are there?
down (nessoptiles)
Flight
Contour
Semiplumes
What are the components of feathers?
Keratin
Melanin
Carotenoid pigments
How are colours made in feathers?
White: caused by reflection of all wavelengths
Blue: caused by reflection of incident light from turbid porous layers over melanin
Irridescent colours: generated by interference
Are feathers dead or alive
Dead, but during growth are full of blood vessels
What’s a contour feather
Cover the body
Symmetrical
What’s a down feather
Soft and fluffy
Trap air and create layer of insulation
What are bristle feathers?
Stiff shaft with barbs only on base
Around eye, nose, bill and as eye lashes
What are filoplume feathers?
Hair like
Very fine shaft with a few short barbs at end
Function as pressure and vibration receptors
What are semiplume feathers?
Fill in between contour and down feathers
Have veiny barbs near shaft which break down to fluffy stuff
Where are the primary flight feathers attached?
Hand bones
Where are the secondary flight feathers attached?
Attached to ulna
What’s a quill knob?
Where feathers are attached to forelimb bones in birds, indicated that some dinosaur species had feathers including velociraptor
What extra layers of feathers are there covering parts of the primaries?
Lesser coverts
Median coverts
Greater coverts
What is the alula,
Important for flight, attached to base of thumb
Can move independently from rest of hand
What is emargination?
A thinning of the width of the feather at a distance down the flight feathers
It causes gaps in wing tips, forcing air up through the gaps leading to increased lift
What are pterylae,
Discrete tracts of contour and flight feathers growing down the body and wings
What are apteryia
Spaces in between covered with down and semiplume
What is birds skin like?
Loose thin and dry
No sweat glands, only cutaneous gland is the uropygial (preen) gland
How do birds keep feathers in good nick?
Uropygial gland at base of tail excretes waxes, fatty acids, fat and water to coat feathers
What are the structures of the feather?
Quill, shaft, barbs, barbules, hooks and ridges, vanes
What are the potential stages during feather development?
- filamentous -> downy -> vaned
OR - strap -> vaned -> downy
What are the hypothesised reasons for feather development?
- flight (not supported by fossil evidence)
- insulation
- display
- prey capture
- temperature regulation
What roll does the tail have in flight?
Minimises drag
Control
Additional lift at low speeds
What types of birds use feet in flight and how?
Webbed feet in water birds, use for lift control and stability
What is moulting In birds
Periodic shedding of feathers
Why do birds moult?
Feathers wear out:
- Inefficient in flight
- Inefficient for insulation
- Inefficient for waterproofing
- Dull and not good for attracting mate
What can wear result from
Abrasion UV damage Bacterial activity Mallophaga General wear and tear
What does melanin do to feather structural strength?
Increases it
Strips of dark will be less worn away on feathers
What’s the 3 part plumage sequence of birds in their lives?
Nessoptile - few down feathers on feather tracts
Juvenile - bird starts to develop its main body feathers, but lacks ability for sustained flight
Adult - fully developed feathers
What moult types are there?
Partial - body only (juvenile moult is partial moult)
Full - body and flight feathers
Where does moult start on body and wings?
On body starts from center of dorsal tract
On wings, starts at shoulder, moves down the wing
Why do birds migrate?
Follow food:
Within a season (hard weather movements)
Between seasons (seasonal migrants)
How many birds in Europe and Asia are involved in autumn migration per year
5 billion
For how long can warblers fly non stop
86 hours, north to South America
How many miles do bristle thighs curlews fly between winter and breeding
2000
What are true migrants?
Birds that move long distances, retain historical patterns of dispersal
What are the costs vs benefits of migration?
Costs: increased mortality risk
Benefits: favourable conditions elsewhere or increased breeding success
What are the sources of fuel for migration?
Mainly fat: small migrants increase upto 150% mass in fat (eg. Garden warbler increase by 60%)
Flight muscle mass needs to be increased to generate additional power to carry extra weight
How much more energy per gram does fat have than protein and carbohydrate
Twice as much
Birds with large amounts of fat can fly how far?
2000km in one flight, for example birds need to fly across Sahara desert in one go, 600 miles!
How do some birds show phenotypic plasticity for flight?
Reduce size weights of body organs - consequences for refuelling
What causes migratory behaviour?
Changes in photoperiod, which results in increase in thyroid hormone (TH)
What does increase in TH also cause?
Moult
What are the 3 important processes in migratory species
Migration
Moult
Reproduction
- only do them one at once
How do we know where birds go?
Ringing, in use since 1909
