week 8 - birds Flashcards
diversity of birds
very diverse
how many species are there
- 11,001 according to IOC checklist
- How many depends on which phylogeny you use
- Splitters and lumpers
Aves
the class we call birds
- Comprises 200-400 billion birds falling into 44 orders, 253 families and 2,376 genera
- All avian orders are completed by the term ‘formes’ which means ‘taking the form of’
egg diversity
- Massive variation between eggs of species in terms of:
o Number laid in clutch
o Base colour
o Size
o Speckles and spots - Even large intraspecific differences exist
- Usually one egg daily until they have a clutch (a collection of eggs)
- Turns out there is inherited patterns of spotting in some species
egg shape diversity
- Shape of a way of cleaning themselves
- E.g. if covers in poo cannot hatch
nest diversity
Some species spend ages
Some don’t
* Doves and pigeons
o 2 days everyday cant spend time building nest
o Almost an afterthought
Mound builders
Huge piles of vegetation
* On and off mound to regulate temp (incubate eggs)
Hatch as chicks and emerge out
Well camouflaged eggs
Run away as if broken wing to draw
Tunnels and chambers
predator away to protect eggs (distract)
in most species flight has driven body mass reduction:
how?
- Lost teeth
- Lost structural bone
- Lost skeletal elements
- No viviparity but lay (external eggs)
- Only one functional ovary at any one time
- Massive diurnal fluctuation in fat reserves
bird anatomy and physiology highly conserved
- Skeletal elements fused
o To create rigidity of flying structure - Long bones air filled
- Medullary bone
o Honeycombed type of bone (just not as strong) - No teeth but gizzard grinds food instead
o Teeth are too heavy - Large flight muscles
- Air sacs as well as lungs
o Huge amounts of O2 to active muscles
o Flight had huge energy costs - Most body weight near centre of gravity
o Wouldn’t want to develop eggs that are inside body because too heavy - Feathers
- Calcified egg shells
skeleton
important elements
Furculum
Keel
Tarsometatarsus
Tibiotarasus
Synsachrum
Pygostyle
digestive system
important elemements
crop
proventriculus
gizzard
caecum
cloaca
vent
respiratory system
important elements
lung
subscapular airsac
carvical airsacs
anterior thoracic airsac
abdominal airsacs
posterior thoracic airsac
reproductive system
growth and reduction of structures depending if they are in breeding or not
internal anatomy of egg
see notes for diagram
the chalaza keeps the yolk in the middle
wing
for function
flightlessness and body plan
flightlessness has freed some species from overall body plan
avian foraging strategies
range of food types so need…
specialised digestive machinery and specialised feeding behaviours that together allow birds to use foraging niches exclusively, reducing competition with others of the same species (or conspecifics) and with birds of other species (or heterospecifics).
avian foraging strategies
specialised foraging behaviours
- Skimming
- Ambush
- Pursuit
- Plunge diving
- Hooding
- Ossuaries
- Larders
- Tool use
- Pack hunting
avian foraging strategies
birds eat everythings:
- Generalists (or omnivores)
- Specialists
o Insectivores (tend to be song birds)
o Piscivores
o Carnivores
o Frugivores
o Nectarivores
o Granivores
o Graminivores
o exudativores
how do birds forage?
- Specialised bills
- Specialised feet
- Specialised digestive machinery
- Specialised behaviours
avian foraging strategies
specialised bills
large diversity
relates to how each bird hunts
avian foraging strategies
specialised bills
the flamingo
Sieving water with particulate matter in it
Swallows the important food
avian foraging strategies
specialised bills
wader bills
The way species separate themselves across available habitat
Specialise in different bill types
avian foraging strategies
specialised bills
bills and speciation - darwins finches
- Adaptive radiation on the Galapagos islands
- Wide range of food types by using bills to extract:
o Termites
o Insects
o Blood
o Eggs
o Fruits
o Pollen
o Leaves
o Buds
o Seeds - Bill shape can explain how species evolve to have different foo types
avian foraging strategies
specialised feet
- Feet are generally specialised for locomotion
- However, spme are for feeding
o E.g. hunt and carry heavy fish
o E.g. foot osprey
