Evolution and Diversity of Birds Flashcards
What feature defines birds?
Feathers
What living tetrapod group is the closest relative to birds and what is the name of their shared common ancestor?
Crocodilia
Archaeopteryx
What is the scientific name for birds?
Aves
What were the four main features of Archaeopteryx?
Feathers
Wing claw (reptilian)
Toothed beak (reptilian)
Long tail with many vertebrae (reptilian)
Name the 5 types of feathers possessed by birds
Contour Semiplum Filoplume Bristle Down
What are the features of contour feathers?
Gives bird smooth characteristic shape Helps with streamlining of flight Flight and tail feathers are modified versions of contour feathers First level of defence Visual colouring
What are flight feathers also called?
Remiges
What are tail feathers also called?
Retrices
What two pigments are used in visual colouring of contour feathers?
Melanins (black/grey/tan)
Carotenoids (red/orange/yellow)
Which of the two pigments used in contour feathers can only be obtained from the diet of birds?
Carotenoids
What two structures use incident light to give colour to contour feathers?
Reflectance (blue/green)
Interference (iridescence)
UV reflectance also important
What is the name for a bird’s distinctive outer covering?
Plumage
What are the three parts of contour feathers holding them in place?
Rachis
Barbs
Barbules and hooks
What is the rachis?
Hollow, central shift providing backbone
What are barbs?
Extend either side of the rachis - the site of most pigments
What are barbules and hooks?
They create stiffness and flexibility and fasten feathers to one another
What are the characteristics of down feathers?
Much smaller than contour feathers
Lack barbules and hooklets
Soft and fluffy
Insulation
What are the characteristics of semiplume feathers?
Intermediate in shape
Found between contour and down feathers
Help with insulation and to keep form of contour feathers
What are the characteristics of filoplume feathers?
Hairlike - a few barbs at tip
Covered by other feathers
8-12 found around each contour feather
Pressure and vibration receptors to keep contours in correct shape and form for the environment
What are the characteristics of bristle feathers?
Stiff, a few barbs
Occur around eyes and mouth of a few bird species
May be protective / act as a filter / act as funnels for insectivores
What is crypsis?
Blending into background to avoid detection by predators or prey
Behavioural traits to match
What are the two purposes of the appearance of feathers?
Crypsis (camouflage)
Attraction - brighter males attract more mates, whilst females drab to escape predators
Why is it so important that feathers insulate birds?
Vital for endothermy - birds have body temp of around 40 degrees - higher than mammals
Fender plumage in winter
Why do birds preen?
Restores feather structure, cleans plumage of ectoparasites and dirt
Applies waterproofing oil
Allows bonding as birds prune each other
What are the 5 ways birds take care of their feathers and allow replacement of feathers?
Preening Bathing Sunning Anting Moulting
What gland in birds produces oils for waterproofing?
Uropygial gland
What is the name for when birds preen each other allowing bonding?
Allopreening
How do birds bathe and what is the issue with it?
In water or sand, but birds are vulnerable to predation afterwards as they are waterlogged so cant fly as effectively
Why do birds use sunning?
To gain vitamin D
To soften old waxes so they can be removed more easily
To make ectoparasites more active so they can be spotted more easily
What is anting and why is it done?
Birds lie on ant nest and allow ants to crawl on them
Ants produce formic acid which may benefit the birds by killing mites
Ants may remove ectoparasites
What is moulting and how often does it happen?
Replacing old feathers with new ones in orderly predictable sequence
At least once a year
Why can moulting have issues?
Takes lots of energy so not done when breeding / migrating
Besides feathers, what other features do birds possess?
Forelimbs modified as wings
Feathered tail - no bones so lighter
Toothless horny beak - teeth too heavy
Endothermy - can live in extreme environments
What 4 major groups of animals have evolved flight?
Pterosaurs
Bats
Insects
Birds
What 5 adaptations have birds got that allow them to fly?
Feathers Lightening of body Strengthening of skeletal structure Large brain and sensory organs to process sensory info Wings
What are the characteristics of feathers that help birds to fly?
Insulation Lightweight Strong Makes bird streamlined Surface is flexible
How has a bird reduced it’s weight for flight?
Lighter skeleton - reduced number of bones, bones hollow and lack marrow, skull has lost heavy jaw
Beak is toothless
Reproductive organs enlarged seasonally
Oviparous (eggs laid then incubated externally)
How is the skeletal structure strengthened?
Fusion of bones - keel and wishbone
Muscles - to power flight
What muscle powers the downward movement of wing and what percentage of a bird’s body weight is it?
Pectoralis
Up to 35% of body weight
What muscle pulls wing back up after downward movement?
Supracoracoideus
What is the keel of a bird?
A ridge along the breastbone of many birds to which the flight muscles are attached
What is the wishbone and what is it’s other name?
Furcula
A forked bone found in birds formed from the fusion of the two clavicles, which strengthens the thoracic skeleton to withstand the pressures of flight
What is the clavicle?
Collarbone
How many other wing muscles are there besides the pectoralis and supracoracoideus?
48
What is a bird’s main sense?
Sight
Why do birds have comparatively large brains and eyes?
To process large amounts of sensory information during flight
How are wings shaped - describe
AIRFOIL shape, rounded front edge and tapers down to point at rear