convergent evolution
When two unrelated species end up looking the same physically
can obscure true evolutionary unrelatedness
prehistoric
some had teeth
the evolutionary advantages (functions) for the development of feathers
insulation - thermoregulatory control of body temperature
camouflage and/or social signaling - feathers contained melanosomes (pigmented color and iridescence)
tail feathers to display sexual dimorphism and/or anti-predator defense mechanism (stress induc
Archaeopteryx
hollow bones
Arboreal:
lived in trees or climbed trees and started flying by gliding down from branch to branch or tree to tree
Cursorial
implies that basal bird species ran along the ground with their forearms outstretched for balance as they pursued prey or ran from predators. Forearms covered with feathers would have increased lift, and as these feathers grew longer and stronger, more li
Galliformes
(landfowl: turkeys, chickens, pheasants)
Neognathae
Further agreement that the Neognathae group can be subdivided into Neoaves and Galloanserae
current population trends for birds
1 out of 8 will be extinct in our lifetime
overall population decrease 20-25%
40.3% of extant populations have declined
the repercussions of reduced bird numbers: name 2
Indicates degradation of original habitat
Rodent populations swell
Decrease in carcass clean up-- increase disease
Less seed dispersal and poor germination rates
More crop damage (due to more insects)
Entertainment and recreation decreases
factors that predispose animal species to endangerment name 2-3
Commodity
Dangerous
Specialized habitat/diet
Small geographic range
Inability to fly
factors that cause endangerment
#1: farming
Logging (cutting down trees)
Invasive species
current major threats to bird populations: know these three specifically
Agriculture, logging, invasive species
Advantages of flight:
Birds can go where predators can't (defense mechanism) to build nests
Can get away from predators quickly
Disadvantages of flight
1) you have to make all the power yourself, you don't have the boost of an engine.
2) you have to do an annual moult, during which time your feathers are less efficient.
3) some types of birds (eg male peacocks) have developed feathers to attract females
the need for torpor (hibernation-like sleep) in hummingbirds
Save up to 60% of their energy
Makes their bodies more efficient
Helps cope with unpredictable food supply (i.e. birds that catch insects or feed on nectar or fruit)
falcon vs crane and condor
Captive breeding and release over 25 years of peregrine falcon- now 4800 population
Whooping crane is not very self-sustaining once released- still threatened by power lines
California Condor captive breeding program but still threatened by lead poisoning
Melanin
black coloration and most of the brown, rufous, gray, and buff colors
Carotenoids
red, orange, yellow of plumage (obtained through diet)
Porphyrins-
brown and rufous color for several birds including owls
Psittacofulvins
parrots synthesize these and they are responsible for red, orange, pink, and yellow
molting
shed old feathers to make way for a new growth.
Replace old feathers with new feathers
Occurs at least once a year
Ensures that birds will be able to maintain flight ability in their adult lives
Allows for seasonal change in appearance for mating or camou
Monocular vision:
(vision with one eye) and its association with wide visual fields allows birds to detect motion and potential predators for their survival? bird can see 300 degrees
Binocular vision:
is excellent for depth perception, and thus, judging distance, as the input from both eyes is needed to compute the distance of the visual target
bird
all feathered animals
unihemispheric slow wave sleep (bonus)
Sleeping with one eye open and half the brain awake
the overall basics of sound production by the syrinx
The temporal pattern of vocalization is determined in large part by contraction of the thoracic and abdominal muscles that control the airflow coming from the respiratory system that passes through the syrinx
evolution tools specific to niche
-Sense of smell highly developed in kiwis
-End of bills sensitive to touch in shore birds
-Webbed feet common with water birds to help swimming
-The green heron throws earthworms and insects into water to catch minnows
Crop (the outpocketing at the base of the neck):
Can be unilobed, bilobed, spindle shaped, or absent
Temporary storage space for potential food; Food can be stored and then digested, reducing the length of the nighttime fast - this is critical for species with high metabolisms
Transport food and water t
Proventriculus
first chamber of the stomach
Comparable to mammalian stomach
Highly glandular; secretes hydrochloric acid, pepsinogen, and mucus; pepsinogen is converted to pepsin, a protein-digesting enzyme
Gizzard:
Mechanical breakdown of food
second chamber of the stomach
Site for gastric proteolysis (protein breakdown)
Oviparous:
internal fertilization, but the development of the embryo occurs outside the mother's body within an encased egg that provides the nutrients for its development and growth.
All birds are oviparous
Long cues for reproduction
increasing day length (birds that respond to this cue are long-day breeders; penguins are short-day breeders and initiate reproduction in response to decreasing day length), increasing environmental temperatures, and increased food supply
Medium cues
more important closer to the equator where day length changes less): establishing a territory and an adequate food supply
Ampulla or magnum
secretes more than 40% of albumen (egg white)
lack of the right ovary and oviduct, regression of the left ovary and oviduct in
non-breeding periods
...
male reproductive characteristics
-production of a lot of sperm compared to other animals such as humans or farm animals to make up for increased sperm mortality, and quick maturation time of avian sperm
why do some havea penis
water damage and sperm competition
how do they mate
female choose male based on genetic potential
speckled eggs
layed by ground birds for camo
determinite egg layers
female bird species that enter the reproductive season with a set number of eggs that will be produced and are unable to produce a second clutch of eggs if their eggs are destroyed during a reproductive season
indeterminite egg layers
: If her first clutch of eggs was consumed by a predator during incubation, a bird would be able to produce another clutch of eggs that same breeding season
Precocious chicks:
Turkeys, chickens, & ducks
Leave nests within 24 hrs of being born
nest on eggs
very developed & independent
eyes are open and walking
able to keep themselves warm
food goes towards motor function & growth
develop slower once hatched
Altricious chicks:
Song birds
in elevated nests & need protection until they can fly
born featherless
eyes aren't developed & completely dependent for food
Protection
Warmth
all food eaten goes towards their growth
Synchronous hatch
begin to incubate only after all eggs are laid
asynchronous hatch
eggs hatch in the order laid (generally happens)