Response to Food Availability
o Track ephemeral food resources
o Responding to annual variations
o Concentrating in local habitats
o Switching food types
Influence of food on spacing patterns
Food is rarely randomly seperated, territory size is larger with low food density, and smaller with high food density.
is flexible, but risky. Try's new things, more adventurous. Popular in stable, predictable environments.
excessive ingestion of food that is typically seen in birds right before migration. Foraging rates can double!
stored food, some birds have communal granaries that they store food for their community.
Optimal foraging theory
Energy profit is equal to the difference of the energy gained from the energy cost, dividied by foraging time. Remember the Great Tit example with the conveyor belt,
Account for 2-9% of body mass, and highly misunderstood aspect of birds because they are really intelligent.
Species with variable food resources...
Species that tend to have variable food sources, are thoguht to be more intelligent as they have learned to utilize more food sources. Intelligence roots in necessity.
Avian nervous system
- Obtain information
- Analyze and repsonse
- Store information
- Coordinate motor impulses
Includes the cerebellum and medulla, which will integrate muscular control and coordination.
plays most in memory, study on its relationship between brain evolution and social behavior.
formation of new neurons to replace old ones and reallocate brain space appropriately to seasonal efforts.
Three stages of sleep
1) slow-wave sleep (SWF), 2) intermediate sleep, and 3) rapid eye movement sleep (REM).
contractions cause change in the curvature of the cornea and thus amount of refractive light.
large, black pigmented, pleated and vascularized structure attached to the retina near the optic nerve.
Concave depression which are sites for visual sharpness.
o Raptors can have 6-8 temporal fovea
o Shorebirds have ribbon like strip fovea (horizon)
common in hawks and raptors, magnifies image, length and width of eye are about equal, which enlarges retinal image.
common in owls, adapted for low light levels, long optical axis and huge cornea and pupil serve to increase light gathering ability.
ability to discriminate two points as being two points or, in other words, the ability of an observer to resolve fine spatial details. Most birds can resolve up to 100hz.
locate positions of sounds by integrating differences in timing and intensity in left and right hear. Common in owls.
pressure sensitive corpuscles that are onion like layers of which allows for elastic reception and transfer of rapid pressure changes. Abundant in the bill tips of sand pipers and sipes, also woodpeckers. Also located at feather follicles.
chemical reception like smell. birds have very poor smell. Vulture have enlarged olfactory bulbs, Tube-nose birds have well-developed tubular nostrils that can pick up fish oil and dimethyl sulfide. Honey dues can smell honey.
Pure or nearly pure sound waves - higher the pitch the higher the frequency of wave oscillation
comprised of several frequencies that are multiples of each other, different octaves.
control the details of the syrinz action during song production. Most non passerines have two muscles, while Passerines can have up to 6-8.
Three hypotheses for song repertoire
Thwart neightbors ability to track movement
Prevent declining interest
Four periods of song development
Critical learning period -> Silent period -> Subsong period -> Song crystallization
breaks up the shape and destroys the outline of an object, hindering detection
Pigment is darker dorsall, and is thought to have an adaptive effect of reduciing conspicuous shadow cast on the ventral region
different plumages as young than as adults. Dull plumage gives the appearance that the bird is in its first year or youth.
Three hypotheses for Rituals
To increase efficiency of communication
To increase clarity of intent
odd behavior where birds foster either hostility or cooperation. Intereactions between partners often start this way.
birds face seasons of stress and opportunity that correspond to predictable calendar changes in day lenght, climage, and resources.
Cover -> Spring break up and bonding -> Nesting and brooding -> Brooding and late nesting -> fall shuffle.
having a periodicity of 1 year, used to regulate timing of molt, breeding, and migration.