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.
The sense of where muscles, feathers, and limbs are in space.
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.
good for contact calls
Long high notes
good for alarm calls
low frequency songs
good for long distance and high interference habitats
high frequency songs
good for open habitat with low interference.
formed at the junction of the two bronchi/trachea. Air vibrates the tympaniform membrane
control the details of the syrinz action during song production. Most non passerines have two muscles, while Passerines can have up to 6-8.
Signal potential rivals that a sit is occupied/defended Advertise to unmated females
Differences in pitch, syntax, and timing help bird differentiate each other.
Three hypotheses for song repertoire
Sexual selection Thwart neightbors ability to track movement Prevent declining interest
Four periods of song development
Critical learning period -> Silent period -> Subsong period -> Song crystallization
inconspicuous coloration that blends in with the background
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
there is darker pigment ventrally opposed to lighter pigment dorsally
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 Graded displays
odd behavior where birds foster either hostility or cooperation. Intereactions between partners often start this way.
the differences between males and females in regards to size and plumage
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.
Bird energy goes to what?
reproduction molting migration
having a periodicity of 1 year, used to regulate timing of molt, breeding, and migration.
The duration of an organism daily exposure to light.
argued that predatory birds selectively search for particular cryptic insects.
documented that some birds are reluctant to try new situations when foraging; whereas others are not reluctant.