|
In the mid 1970s, my
father purchased a parrot from a Brooklyn pet store, without much
though about where the bird originated. Charlie (as the Yellow-Crowned
amazon, Amazona ochrocephala,
was soon named) differed from most of the pet parrots I’d seen in
one particularly striking way: he produced an abundance of highly
complex sounds, compared to the much simpler sounds produced by
captive-reared parrots -
or those taken from wild nests as chicks, before they have had a
chance to learn the sounds produced by members of their species in
their natal environment. I have since come to understand that he
brought these complex sounds with him on his long journey from the
wild. Additionally, Charlie’s left wing did not have, and
subsequently failed to regenerate, primary flight feathers. I learned
that this condition is not unusual for birds caught from the wild as
free-flying adults or subadults. Often the poachers will clip or cut
the primaries upon capture, and any damage to the skin of the wing can
inhibit subsequent feather growth. Or, birds whose feathers are not
cut as such may damage them during the stressful early days of
captivity by flapping their wings against the bars of a confining
cage. I always knew that Charlie was quite out of place in New York
City, but any hopes of someday returning him to his natal population
were dimmed by his lack of these feathers, so critical for controlled
flight.
Years later as a
student in my first year of graduate school, while on a Tropical
Ecology course field trip to Venezuela, I had my first opportunity to
see parrots in the wild in a lowland rainforest area, Tico Poro. As
luck would have it, they were Yellow-Crowned amazons gathered in a
fruiting tree just after dawn, behind a small roadside restaurant, and
I watched and listened raptly, while my classmates slept back at camp.
Though the Yellow-Crowns made sounds which were somewhat different
from those made by Charlie, the quality of their voices seemed
nonetheless quite familiar to me, and I felt a sense of kinship with
these wild birds, engendered by my close relationship with Charlie. I
was also struck by the contrast of their flock-based society with the
much more solitary lives of the captive parrots I had seen, the space
of whose lives are often constricted to the volume of their cage, or
at most, to the volume of the homes of their owners. What had always
been a sense of injustice about whatever events has transpired to
remove Charlie from such a flock and ship him to New York to become a
captive apartment dweller burgeoned within me into a sense of
obligation. Though I could never return him to the wild, perhaps I
could do something to help ensure that other wild parrots, living free
among their own, might not suffer the fate of his own dislocation.
When I returned from
Venezuela, I was curious about how Charlie would respond to the
recording I had made of the wild flock; if I could not bring him to
the wild, perhaps I could bring the wild to him. In the past I had
played his own recorded vocalizations back to him, and he was always
stimulated to sing along, or even to circle the speaker avidly,
apparently in search of the parrot singing within. I anticipated that
the recording I was about to play to him would elicit an even more
dramatic response, as it was from numerous individuals of his species.
But quite to my amazement (and dismay), as I started playing the
recording for him, he continued to preen himself disinterestedly.
Whatever interest he did express was no different from his response to
any loud sounds, and certainly came nowhere near the reaction elicited
by his own voice, his own sounds. I subsequently had the chance to
play for Charlie recordings of his species that I made in Peru, and
the effect upon him was the same: indifference.
It occurred to me that
the differences between his wild-type sounds and those of the
population I had recorded, though perhaps subtle to human ears, may
have been profound enough in his ears to preclude any sense of
recognition Charlie might have otherwise had, if the recording had
come from within his natal population. The body of work I undertook in
my graduate studies, on a species closely related to Charlie’s, was
born out of this initial conjecture about the importance of the
precise form of a parrot’s calls for recognition. If a close match
between the stimulus vocalizations and the respondent’s own was
indeed necessary to elicit the level of response I had seen in Charlie
reacting to his own vocalizations, how would this shape the learning
strategy of a young parrot? How would such social discrimination shape
the differences in vocal repertoires among individuals within a
population? Among populations within a species? Among species?
These are the questions
which formed the conceptual basis of the work I conducted as a Ph.D.
candidate at Harvard … in a nutshell.
A
Closely Related Species: The Yellow-Headed Amazon
The
Yellow-Headed amazon parrot, Amazona
oratrix, is one of the premier talkers of the parrots. Their
scientific species name “oratrix”
is Latin for “she who speaks.” They have a very long lifespan,
rivaling our own, and form long-term pair-bonds with their mates. They
are also highly prized by the pet-trade ($800 to $1,500 in New York
City), and so wild populations are in peril, as they face the combined
threats of deforestation (they nest in old, hollow trees) and capture
for the pet trade. The profits from parrot smuggling rival those for
cocaine, pound for pound. Thus, there is real incentive for people
from poorer countries to poach nests and send the fledglings
northward.
Some
Observations from the Wild
Within
an area, each pair of parrots (or occasionally a trio) has a stable
home range from year to year, and all of the oratrix
parrots in a given area share a common “lexicon” of sounds. These
sounds, though learned, appear to be highly stable through time and
across a wide geographic area. When I traveled to a location 60 miles
north of my main study area, I found that the parrots there were using
the same vocabulary, or vocal repertoire, as the parrots further
south, though there were some noticeable differences. The northern
parrots speak with a different “accent,” equivalent perhaps to a
“northern drawl.” The similarities, though, strongly imply that
the two sites are not isolated from each other, but form one
continuous population. This conclusion was given more credence when I
recorded a juvenile at the main field site that had the northern
accent, indicating that this juvenile was an immigrant who had come
from the northern area.
At
another site, about 80 miles inland from my main study area, I found a
population that possessed a vocal repertoire which was entirely different from the coastal populations. This difference was
not like an “accent” when using the same words. I could not find
equivalent sounds. It is more like differences among human languages
or musical traditions. This seems to imply that this inland population
has long been isolated from the others, at least long enough that they
would form their own “oral traditions.”
I
then performed a crucial experiment back at the main field site. Using
tape recorders and loud speaker-horns, I played back recordings made
at each of the three sites to see how the parrots would respond to the
differences. They responded (by vocalizing and approaching) to tapes
from their own and the similar-sounding population, but hardly, if at
all, to the tapes from the different-sounding population, as if they
did not recognize that it was from the same species. I interpret these
results as follows: If a parrot spends a lot of time and energy
vocalizing, it is doing so to get and to hold the attention of the
other parrots in an area (“Over here! Look at me!”). If the
listening parrot ignores sounds which are very different from those it
is familiar with, then there would be a strong social pressure for the
singing parrot to conform to the local dialect in order to get the
attention it seeks (and we all know how parrots are big hams when it
comes to getting attention). Thus, parrots which are better imitators
can get more attention from their intended audience.
At
another site, I made some recordings that I then compared (using a
computer) to a recording that was made in the same vicinity in 1961
(which I got from the Cornell Library of Natural Sounds). Much to my
amazement, some of these 1961 sounds were still being used 34 years
later. So, it seems, these parrots are rather conservative when it
comes to changing their vocal repertoire.
Also,
for these parrots, vocal imitation is limited to members of their own
species. Though there were three species of amazon parrots at my main
field site, there was no evidence that they were imitating each other,
or any other species for that matter. This is in direct contrast to
the African Grey parrot, also a renowned talker, which has been
documented to imitate the sounds of other species in the wild. So it
appears that whatever social factors are at work in shaping learned
vocal repertoires in the “talking” parrots, there are different
forces in play in different species.
What’s
All the Chatter About?
After
standing in the field with them month after month, then year after
year, I began to see that many of their vocalizations have a clearly
contextual function, such as coordinating a pair’s movements when
they are about to fly off (“c’mon, let’s go!”), or to keep a
pair in contact when they separate (“over here!”). The vast
majority of their complex sounds, however, may have more in common
with music than with speech. By this I mean that there are regularly
repeated patterns, and often seem to be given in more of a one-sided
performance than an interactive dialog. How can we ask what a parrot
“means” by these vocalizations? Let me draw an analogy: When we
hear a saxophonist playing his solo, what does he say through the
notes he chooses? Well, he’s telling us about his stylistic
background (Is he a jazz musician? A blues man? Classical?); about his
proficiency (Is he a musical genius, or just a journeyman? Is he just
starting out, or an old pro?). He may also be making references to
other bits of music from within his genre (as when we recognize a
snatch of melody from another song go by), but these are only apparent
if we, the audience, share his stylistic background and recognize
these musical references and quotes. Thus, though he may not be
speaking with words, the saxophonist is actually communicating quite a
bit about himself. These same kinds of information may be communicated
by singing parrots (where they come from, how proficient they are, how
old they are, how vast their recollection of sounds is, etc.).
Of
course, if the parrots were speaking about last week’s weather, how
would we know?
Some
Potential Applications of My Results
The
stability of parrot vocalizations within an area through time means
that we can answer questions about whether populations are connected
(as when I recorded a juvenile from the northern site in my main field
area). We can even learn from where confiscated parrots are being
poached (I think again about Charlie, and someday finding a population
where they all speak the same “language” as him). For example,
tapes I got from a woman in Wisconsin indicate that her bird was
wild-caught from the northern population. I have since heard from
others who have heard the recordings on my web site, which match the
vocalizations that their own companion parrots make. Hopefully, we can
use this information to target law enforcement and education campaigns
to those areas from which parrots in the wild are still being
harvested illegally.
Also,
with the production of my film on the lives of free-living parrots,
“Stalking the Wild Amazons,” I hope to help replace the popular
perception of parrots as cute little caged clowns (as in the movie “Paulie,”
which no doubt created a run on parrots as pets, as did “101
Dalmatians” for those dogs) with a more realistic, and hence more
sympathetic, view of wild parrots. Hopefully we can redirect some of
our love and appreciation for parrots away from some of the
potentially destructive aspects of the pet trade and into a more
conservation-minded perspective, eco-tourism to where they still fly
free, and support for wild parrot conservation efforts.
Lastly, by expanding
the broad front of research on animal communication to include
parrots, we may come to know more about the origins and evolution of
that aspect of ourselves which makes us uniquely human: our language.
We just might discover that we are not as unique as we have thought,
and that the bright light of our intelligence is, in fact, visible as
a spark of cunning in numerous other species as well. Perhaps
evolution will eventually fan this spark into a bright flame, if we
can preserve these species long enough for it to do so.
For more information
about my work and the fascinating lives of parrots in the wild, or to
obtain a copy of “Stalking the Wild Amazons,” a one-hour
documentary on the lives of wild parrots, please visit my website: http://surf.to/parrots,
or write to me at 23 Sacramento Place, Cambridge, MA 02138.
|