Lecture 19: Ontogeny of Behavior II

Early Experience and the development of Behavior in White-Crowned Sparrows

• young males hear father’s songs, and produce sub-song (rambling series of syllables that do not occur in Father's song)

• after 3-7 months: produce plastic song (some recognizable syllables of father’s song)

• after 7-9 months: produce full adult song

Evidence for bird song learning

• if young males hear adult song bertween 10-15 days post-hatch (critical period) song develops normally

• playback of songs before 10 days, or after 50, does not allow for song learning

Critical Period

periods of susceptibility to environmental stimuli. They are brief, well defined, species-characteristic, have irreversible effects on behavior

sensitive period

more commonly when learning occurs. They are fairly extended, not as well defined rather gradual, differ in duration, and reversable

Phases of song development in white-crowned sparrows

• Sensory Phase: song is acquired from a tutor and is saved in memory

• Sensorimotor: rehearsal of song, matching sound to template in memory. Song is crystalized

Timing of sensory and sensorimotor phases in Brown-headed Cowbird

are brood parasites, so during first spring young experiences songs of host species. Their sensory period is delayed until following spring

own species bias in song learning

members of each species selectively learn song from conspecifics that is the product of physiological constraints:

• sensory receptors tuned to frequencies of conspecifics

• effectors are structurally specialized to produce species characteristics song

• central neural network that is maximally responsive to own species song

Song Tutor Choice

• young may be biased towards learning from their own parent

• song learning appears particulalry sensitive to aspects of the social environemtn

Why do Birds learn Song?

• transmission of complex patterns between generation

• avoid risk of mutation in genetically controlled behavior

• adapt rapidly to physical and social environment

• population regulation

• as well as mate attraction + territorial defense

Why must bird song be learned early in life?

• physiological constraints: developing physiological systems are sensitive to input early in life

• the sooner behavior is learned the better off the animal is: ex antipredator behavior

• reliability associated with successful members of own species early in life: parents are successful model inherently

• species and mate recognition

Imprinting

a form of early learning that occurs during a brief, well-defined period that produces irreversible effects on behavior

Filial Imprinting

process by which young animals form a social attachment to their primary caregiver

Lorenz’s experiments with greylag geese

divided clutches of eggs into two groups:

• hatched by mother→followed remaining in proximity

• hatched by incubator→geese followed first moving object as “mother” (in this case it was Lorenz)

Geese imprinted to first moving object in their environment. Following response is necessary for imprinting

function of filial imprinting

keeps young close to parent

• ensures young remain in suitable habitat

• protects young from dangers

• young in situations to learn other species-typical behavior

Sexual Imprinting

early learning whereby an individual forms an image of what constitutes a suitable male. Occurs after filial imprinting.