Different songs Question 1: song dialect, genetic or environment? Test : rear nestling from 2 locations in isolation Result: nestling never developed full courtship song Test : tutor tapes Result: nesting develop tutor ’ s song

Other results: Only dialect of white-crowned sparrow Critical period (day 10-50) Listen to its own subsong (day 150 – 200) Social influence Learn songs of other species at the presence of social tutor Learn alien song after 50 days old

Specific attribute of nervous system Nerve cells “ record ” information from neighboring birds Neural system follow hierarchical “ decision-making ” tree If visual + vocal cues present, follow visual cue If only vocal cue present, follow own species

Acoustic/brain systems allow individuals to match developing song with “ recorded ” song Song recognition – song practice – song crystallization – further development

Social influence An. Beh. 59: 1187 – 1197, 2000 Hand-reared male song sparrow 2-3 month, rotated equally among 4 tutors that have been neighbors. Housed with one tutor at a time but can hear other tutors month, half rotated again, half stay with one tutor

Learned whole song types Learned songs from multiple tutors Preferentially learned songs that were shared among their tutors Learned songs that other young males in their group also chose

Learned more songs from the tutor they were stationed next to during the later stage Late influence hypothesis

Song control system Observations – Difference in song of male and female zebra finch Genetic difference – male w/ 2 Z chromosomes, female w/ Z & W Differentiation in gonads and hormones Differentiation in the development of song system – (network of neural elements funning from front of brain  spinal cord -  >syrinx

Insertion of estrogen pellets into nestling females resulted an increase in the size of song control system However, w/o exogenous testosterone females won ’ t initiate courtship song (activational effect) Nuclei of song control system are larger in males than in females, larger prior to the onset of singing is spring, shrink after breeding season

Song control system is highly responsive to photoperiodic, hormonal, acoustic and social stimulation Changes in the song learning process correlated with changes in the activities of different genes and the responses of different neurons of the song control system

Different song Question: why species-specific song? Adaptationist hypothesis e.g. species identification adaptive to different habitats Songs of forest dwelling birds often do feature whistle, not trills, w/ frequency below, not above 4 kHz

Nonadaptationist hypothesis – by- product hypothesis – results of geographic isolation Prediction: closely related species living apart: ADA: similar song, NON: different song different species living together ADA: different song, NON: similar song

Results: closely related species at different locations have distinct songs Overlapping species also have species- identifiable songs but regularly hybridize Indigo and lazuli bunting w/ similar songs in overlapping zone, but rarely hybridize  Nonadaptationist hypotheses are legitimate alternatives to adpatationist ones

Why do only males sing? Females of some species sing, too. So, development of song system does not affect reproduction Hypotheses: attract females, deter rivals, mate guarding Prediction/Test 1: females are attractive to male songs

Prediction/Test 2: monogamous males stop singing once mate is acquired, polygynous males continue to sing Prediction/Test 3: females respond to variation in male songs, e.g. complexity New males slower in entering “ vacant ” territory with taped song Muted males less able to defend territory

Song rate peaks when females are fertile Song quality increase with male ’ s physical condition Visit by intruder males will decline with song quality

Are song dialect adaptive Females prefer song of own subspecies  reject nonadaptive hypothesis H1: Dialect communicate origin, allowing females tochoose mates from the some region Prediction/Test 1: females prefer dialect that matches their fathers ’ XX

Prediction/Test 2: Males should not change natal dialect XX H2: dialect allows males to communicate with neighbors Prediction/Test 1: males learn and match their songs with that of neighbors OO Prediction/Test 2: males should “ reply ” to songs of neighbors with matching song type OO

Prediction/Test 3: in species with separate “ for male ” and “ for female ” songs, should get more variability and more complex learning systems in “ for male ” songs OO H3: males are communicating status as neighbors vs. strangers Prediction/Test: territorial males should react more strongly to playback tapes of strangers than of neighbors OO

Crying raven Prediction/Test 1: population dense enough to find each other and carcass quickly XX Prediction/Test 2: parents calling offspring or relatives XX Prediction/Test 3: calling to attract large predators to open carcass XX

Prediction/Test 4: “ dilution effect ” against predator, stop calling after start feeding XX Prediction/Test 5: calling to attract enough juveniles to overwhelm territory owners Resident territory owner never call OO Nonresident should yell when find food OO

Yelling bring lots of nonresident OO Resident pairs unable to defend carcass from groups of juvenile OO Carcass should be fed upon either by pairs or by mobs, rarely by 1 OO