5.2.4.3. The Importance of Social Interaction for Birds
Social interaction strongly influences call learning in budgerigar and chickadee group signatures, and may influence Anna’s hummingbird song and
stripe-backed wren and cacique group signatures. Budgerigars preferentially converge on contact calls of group mates over other birds that they
can hear but with which they have no social contact (Farabaugh et al. 1994).
Young birds copy adults with which they have social bonds even when those
adults give abnormal or heterospecific calls (Brittan-Powell et al. 1997).
Social interaction is clearly important to convergence in chickadee calls.
Isolated juveniles housed together shared the same abnormal song (Hughes
et al. 1998), and adults converged rapidly in D note structure (Nowicki
1989). All male stripe-backed wrens in a group share a repertoire, and all
females share a different repertoire (Table 4.1). Although male group mates
are close relatives and could share songs because of this, female group
mates are not closely related; thus, at least female repertoire sharing results
from social contact. The contrasting support for a critical period in Anna’s
hummingbird group and single isolates could be explained by social factors.
The group isolates had developed social bonds and thus were effective
tutors for each other, whereas the single isolate may not have developed a
social bond with the adult male, making this adult an ineffective tutor. Data
to evaluate this hypothesis are not available in the original paper (Baptista
and Schuchmann 1990). In many birds, social partners are copied, resulting
in acoustic convergence among social groups. In the three best-studied
birds, sensorimotor input and social interaction are necessary for at least
some of call development, and call learning persists well past the nestling
stage.
5.2.5. Relevance to Call Learning in Mammals
5.2.5.1. Sensorimotor Model in Mammals
Very few studies on the effects of deafening or acoustic isolation have been
done in mammals other than primates, making it difficult to evaluate the
importance of sensory input and the sensorimotor or auditory template
models.The data we do have are a few observational studies of normal vocal
development. Studies of sonar signal development in infant bats generally
show that infants begin to produce sonar signals within a few days of birth,
coinciding with the onset of hearing during the second postnatal week in
many species. Infant sonar signals tend to be of lower frequency, longer
duration, show less steep frequency modulation, and be more variable than
adult signals for both constant frequency (CF/FM) bats (Brown et al. 1983;
Habersetzer and Marimuthu 1986) and FM bats (Moss 1988; Moss et al.
1997). An increase in signal frequency corresponds with an increase in auditory responses to high-frequency sounds (Konstantinov 1973; Rübsamen et
al. 1989). The auditory and vocal-production systems develop in concert.
4. Comparative Vocal Learning
205
Social interaction strongly influences call learning in budgerigar and chickadee group signatures, and may influence Anna’s hummingbird song and
stripe-backed wren and cacique group signatures. Budgerigars preferentially converge on contact calls of group mates over other birds that they
can hear but with which they have no social contact (Farabaugh et al. 1994).
Young birds copy adults with which they have social bonds even when those
adults give abnormal or heterospecific calls (Brittan-Powell et al. 1997).
Social interaction is clearly important to convergence in chickadee calls.
Isolated juveniles housed together shared the same abnormal song (Hughes
et al. 1998), and adults converged rapidly in D note structure (Nowicki
1989). All male stripe-backed wrens in a group share a repertoire, and all
females share a different repertoire (Table 4.1). Although male group mates
are close relatives and could share songs because of this, female group
mates are not closely related; thus, at least female repertoire sharing results
from social contact. The contrasting support for a critical period in Anna’s
hummingbird group and single isolates could be explained by social factors.
The group isolates had developed social bonds and thus were effective
tutors for each other, whereas the single isolate may not have developed a
social bond with the adult male, making this adult an ineffective tutor. Data
to evaluate this hypothesis are not available in the original paper (Baptista
and Schuchmann 1990). In many birds, social partners are copied, resulting
in acoustic convergence among social groups. In the three best-studied
birds, sensorimotor input and social interaction are necessary for at least
some of call development, and call learning persists well past the nestling
stage.
5.2.5. Relevance to Call Learning in Mammals
5.2.5.1. Sensorimotor Model in Mammals
Very few studies on the effects of deafening or acoustic isolation have been
done in mammals other than primates, making it difficult to evaluate the
importance of sensory input and the sensorimotor or auditory template
models.The data we do have are a few observational studies of normal vocal
development. Studies of sonar signal development in infant bats generally
show that infants begin to produce sonar signals within a few days of birth,
coinciding with the onset of hearing during the second postnatal week in
many species. Infant sonar signals tend to be of lower frequency, longer
duration, show less steep frequency modulation, and be more variable than
adult signals for both constant frequency (CF/FM) bats (Brown et al. 1983;
Habersetzer and Marimuthu 1986) and FM bats (Moss 1988; Moss et al.
1997). An increase in signal frequency corresponds with an increase in auditory responses to high-frequency sounds (Konstantinov 1973; Rübsamen et
al. 1989). The auditory and vocal-production systems develop in concert.
4. Comparative Vocal Learning
205