Lecture 9 Flashcards
What are the types of feathers?
. Down
. Flight
. Contour
. Semipljmes (inbetween down and contour feathers)
What are down feathers also known as?
Neossoptiles
What are all other types of feathers than down feathers known as?
Teleoptiles (true feathers)
What is the covering of the beak made from?
Keratin
What are the biochemical components of feathers?
. Keratin
. Melanin (pigment)
. Carotenoid pigments (physical colours- yellow and red colours also have colours due to physical mechanisms as well)?
How are the colours of feathers other than those generated by carotenoid pigments (physical colours- yellow and red) generated?
By physical mechanisms:
. White- a colour generated by reflection of all wavelengths
. Blue colours- formed by reflection of incident light from turbid porous layers over melanin
. Iridescent colours (e.g. Hummingbirds) are generated by physical wavelength mechanisms of interference)
What are feathers anchored in by?
The epidermisand
Describe bristle feathers
Stiff shaft and barbs only on the base, or not at all. Occur most commonly around the base of the bill, eyes, and as eye lashes
Highly adapted
Describe down feathers
Soft and fluffy, trap air and Crete a layer of insulation next to the birds body
Where are contour feathers on a bird?
Cover the body
Where are semiplume feathers on birds?
Fill in between contour and down feathers
Describe filoplume feathers
Hairline feathers- very fine shaft with a few short barbs at the end. Typically covered by other feathers: may function as pressure and vibration receptors
Describe contour feathers, why they are like this and what is between them
Fairly symmetrical because they serve an airfoil function in flight but they do form a surface that air flows over (they cover the body). Between them are down feathers
There are specialised much smaller down feathers called what?
Power down feathers
Describe semiplume feathers and what their purpose is
The barbs at the base of the feather has been lost and the barbs at the top remain and they often serve some sort of display function
Which feathers are inserted over the hand in wings?
Primary (provide thrust on the downstroke)
How many secondary feathers do hummingbirds and albatross have?
Hummingbirds: very few
Albatross: lots
Where are the secondary feathers inserted? Where are they inserted?
Over the ulna- so they are imbedded into the skin (the epidermal structures) but they are not inserted into the bone
What are quill knobs?
Where secondary feathers are imbedded into the skin over the ulna. There are ligaments that maintain a connection between the bone and the feather in the skin. So, although the feather is not inserted into the bone there are ligamentous connections that maintain the strength/ integrity of the feather in relation to the wing
What are the discrete tracts of feathers growing down the body and wings called?
Pterylae (contour feathers, flight feathers)
What are the spaces in between the pterylae (main contour feather tracts) called and what are they covered by? Give the difference between temperate and tropical regions in these spaces and why they are different
Apteryia- covered with down feathers and with semiplume feathers a the edges- at least in northern temperate species that need to conserve heat
Tropical species tend not to have feathers on the apteria to lose as much heat as possible
Whether or not the apteryia are covered in feathers depends on what? Give an example
Where he bird lives/ where the species is adapted to live
E.g. in cooler countries the apteryia tend to be covered in down e.g. the UK they tend to be covered in feathers because temperature regulation and maintenance of temperature is important in winter
What kind of structures are feathers?
Epidermal
Describe the skin of birds and how they are different to other vertebrates
Is loose, thin and dry (different to other vertebrates). No sweat glands; the only cutaneous gland is the uropygial gland (secretes oils that the bird uses to coat its feathers)
How are feathers kept in good order?
Preen gland (uropygial gland) at base of tail- waxes, fatty acids, fat and water to coat the feathers and keep them in good condition
Describe the structure of a wing (what it consists of/ what makes up the wing)
. Calamus or quill
. Rachis- shaft (the ridge down the middle of the wing)
. Barbs- originate from the shaft
. Barbules- are smaller structures that originate from the barbs
. Hooks and ridges- in the barbules and these keep the barbs aligned with one another and it is that alignment that gives the feather its function as an air barrier as a surface to generate
. Vanes
Give possible reasons for feathers evolving
. Flight (not supported by fossil evidence)
. Insulation
. Display
. Prey capture
. Waterproofing
. Temperature regulation (as opposed to just insulation)
Give the two hypotheses of the potential stages of he evolution of features (alternative modes)
- Filamentous> downy> vaned (as we see in flight feathers)
2. Strap> vaned> downy (May have started out like strap-like extensions or scales/ skin that differentiated into vaned
What are protopteryx fengningensis?
Most primitive known Enantiornithes, extinct group of birds dominant in the Mesozoic era
(Critical evidence for the origin and early evolution of feathers)
What do strap or strap-like tail feathers resemble?
Both reptilian scales and modern feathers
Give the evolutionary model for the 4 early stages of feathers
- Elongation of scales (on the epidermis)
- Appearance of central shaft (to keep it fairly rigid)
- Differentiation of vaned into bards
- Appearance of barbules and bar ovens
Describe the tail as an additional flight surface
Minimises drag
Imparts control
Additional lift at low speeds
The outer feathers of the tail are adapted for aerodynamic function- asymmetrical- the feathers in he centre are less asymmetrical
Describe the feet as an additional flight surface
Esp. Webbed feet in auks and other water birds- these will also generate lift and impart control and stability
Extend their feet- they provide additional lift and additional movability
Streamlined back-end is important
Reduced drag
Tail feathers are aerofoil
Control and lift
Increases manoeuvrability
Define moulting
Periodic shredding of the epidermal structures called feathers
Why do birds moult?
. Feathers wear out . Inefficient in flight . Inefficient for insulation . Inefficient waterproofing . Dull and not good for attracting a mate
Wear from feathers results from what?
. Abrasion (rocks, vegetation) . UV damage . Bacterial activity . Mallophaga (feather lice) . General wear and tear
What are Mallophaga?
Feather love
What is the structural strength of feathers increased by?
Melanin
What feather wear change?
Colours (display) both in visible and UV spectrum
What are the 2 mould types?
Partial (body only) or full (body and flight feathers
What is juvenile moult? (Processes occurring)
A partial moult (usually)- processes occurring: follicles- neossoptiles teleoptiles; new teleoptiles
In Europe/ Asia how many birds are involved in autumn migration every year?
5 million
Small, new world warblers can fly non-stop for how many hours from where to where?
86 hours from north to South America
What is meant by ‘true migrants’?
Move long distances, retain historical patterns of dispersal
What are the costs and benefits of migration?
Costs: travel- increased mortality risks, imperative to getting back to breed on time
Advantages: favourable conditions elsewhere may lead to higher survival or greater breeding success
How do birds fuel for migration? Give example
Mainly fat: small migrants can increase body mass 50% by accumulating subcataneous and intra-abdominal fat
E.g. garden warbler- normal weight is 16g; autumn weight might be 26g, an increase of 60%
Why do birds increase flight muscle mass for migration? How do they do this? Example
Needs to be increased to generate additional power to carry extra fat load
Some extra protein load can be metabolised during flight as fuel and to maintain optimal power to weight
Sedge warblers Erich 11g in summer so migration weight~ 19g- 172% of normal body weight
How much more energy and water per gram metabolised does fat have than protein or carbohydrates do?
Has twice the amount
What is migratory behaviour stimulated by (example in detail)?
Changes in photoperiod, which results in hormonal changes, particularly an increase in thyroid hormone (TH)
What does increases in TH stimulate?
. Migratory behaviour
. Moulting
What are the three important processes in migratory species?
. Migration
. Moult
. Reproduction
(In general these are only done one at a time)
What is ringing with light, uniquely-numbered metal rings an important tool for?
Ornithological research and conservation (started in 1909)
What new tools allow us to get more information about bird migratory?
. Geolocation
. GPS devices
What cues do birds use to navigate with?
. Sun . Visual landmarks . Stellar compass (& moon) . Olfaction . Magnetic compass (sensitive mainly to angle of inclination of magnetic field not just n-S polarity)
What do displacement experiments show the inexperienced young birds have/ don’t have genetic information about?
The direction and approximate distance of migration, but not that the geographic location of the winter quarters
Genetic data suggest that the directional information is encoded by what?
Only a few major genes
Evolution likely due to assortative mating. What does that mean?
Differential arrival times at breeding grounds
