1. Introduction
First, we hear a rustle in the shrubs, and then a bird whose call sounds like
“where are you?” From a short distance away, another bird gives a slightly
different call: “oh, where are you?” For simplicity, we will call these WAY
calls. In answer, several small gray and white wrens fly toward the first caller,
giving WAY calls that sound virtually identical to the first caller’s. At the
same time, a small flock flies toward the second caller, giving their own WAY
calls. A skirmish follows, with much calling on either side. Careful listening
picks up distinct WAY calls throughout and another staccato call, which
turns out to be a duet. When the dust settles, the small flocks move off in
different directions, territory boundaries apparently stable for the day.
The birds are stripe-backed wrens, and this species lives in stable groups
composed of a dominant pair and their offspring, who cooperate to care for
the pair’s brood (Rabenold 1984). Group mates also cooperate to defend
their joint territory. The dominant pair advertises boundaries by singing
duets, but when a neighbor intrudes, WAY calls provide a means of identifying group mates. All males in a group share a repertoire of about 12 WAY
calls that they use both to maintain contact among the group and to
identify themselves in territory disputes. Female group members have their
own shared repertoire of WAY calls (Price 1998a).WAY calls indicate group
membership—a kind of badge to indicate “I belong to this group.” All
stripe-backed wrens live in social groups, so belonging to a group is
critical. But, how do group members come to share calls? Most group
mates are closely related, so call similarity based on genetic similarity is one
possibility. Yet, calls are passed down along sex-specific lines, and a genetic
mechanism for this is difficult to envision. Instead, it seems that calls are
learned—sons copy their fathers and daughters copy their mothers, and do
so with remarkable precision. Like a surname passed on from father to son,
or mother to daughter (Price 1998a), calls convey family identity (Price
1999). The patterns observed suggest that call sharing is essential to call
function. Although most males in a group are closely related, occasionally
138
4
Social Sounds: Vocal Learning
and Development of Mammal and
Bird Calls
Janette Wenrick Boughman and Cynthia F. Moss
First, we hear a rustle in the shrubs, and then a bird whose call sounds like
“where are you?” From a short distance away, another bird gives a slightly
different call: “oh, where are you?” For simplicity, we will call these WAY
calls. In answer, several small gray and white wrens fly toward the first caller,
giving WAY calls that sound virtually identical to the first caller’s. At the
same time, a small flock flies toward the second caller, giving their own WAY
calls. A skirmish follows, with much calling on either side. Careful listening
picks up distinct WAY calls throughout and another staccato call, which
turns out to be a duet. When the dust settles, the small flocks move off in
different directions, territory boundaries apparently stable for the day.
The birds are stripe-backed wrens, and this species lives in stable groups
composed of a dominant pair and their offspring, who cooperate to care for
the pair’s brood (Rabenold 1984). Group mates also cooperate to defend
their joint territory. The dominant pair advertises boundaries by singing
duets, but when a neighbor intrudes, WAY calls provide a means of identifying group mates. All males in a group share a repertoire of about 12 WAY
calls that they use both to maintain contact among the group and to
identify themselves in territory disputes. Female group members have their
own shared repertoire of WAY calls (Price 1998a).WAY calls indicate group
membership—a kind of badge to indicate “I belong to this group.” All
stripe-backed wrens live in social groups, so belonging to a group is
critical. But, how do group members come to share calls? Most group
mates are closely related, so call similarity based on genetic similarity is one
possibility. Yet, calls are passed down along sex-specific lines, and a genetic
mechanism for this is difficult to envision. Instead, it seems that calls are
learned—sons copy their fathers and daughters copy their mothers, and do
so with remarkable precision. Like a surname passed on from father to son,
or mother to daughter (Price 1998a), calls convey family identity (Price
1999). The patterns observed suggest that call sharing is essential to call
function. Although most males in a group are closely related, occasionally
138
4
Social Sounds: Vocal Learning
and Development of Mammal and
Bird Calls
Janette Wenrick Boughman and Cynthia F. Moss