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By Vicente Jerez Gomez Coronado
Translated from the Spanish by Sebastian Vallelunga
INTRODUCTION
The object in breeding champion song canaries has two fundamental
aspects: the first consists in obtaining canaries with an adequate
genotype, which means we must begin with parents of definite genotype
themselves, derived from lines which were well established previously,
using a process of correct pairing and selection, but once one is
using the preceding process, it is necessary to implement an adequate
program of song apprenticeship among young males, which enables
these already young adults to, with a selected timbre of voice and
notable aptitude, interpret a new and worthy song score. The knowledge
that Timbrado "canariculturalists" have about this learning stage
is fundamentally empirical, based on the experiments of breeders
who have a diligent dedication to the birds. In essence, this knowledge
is founded, in my view, in a fact accepted by all, that canaries
inherit the timbre and other faculties of the voice from their progenitors;
and this leads to two counterposed hypotheses: it is said that the
song, with more or less richness of syllables and concrete musical
norms, must be a spontaneous manifestation of genetic endowment
in conjunction with the influence of the surrounding environment,
while others maintain that for a song to be of high quality, it
must be learned and imitated from adult examples who are their neighbors
during the learning stage. The first group uses no tutors so that
the song will be, as we have said, a manifestation of the genes
and not of an apprenticeship, the lessons of which could be lost
the following year; the second group have their young birds live
near adult examples who can teach them to sing a predetermined song
with perfection.
It also seems accepted by all canariculturalists
that the canary learns his song during a period that runs from birth
until the month of November, and after this learning period the
song "locks" and a stable song is presented. Normally, in the middle
or at the end of October, the young birds are separated from their
brothers and are individually caged to be listened to by the breeder,
either grouped into a team or left as individuals, and trained for
presentation at song contests which are held from November to January.
The training consists, in essence, in keeping them in an enclosure
with little light and moving them, periodically and for a short
duration, to an illuminated site so they will become accustomed
to singing when in the light and so to perform at the moment they
are being evaluated by the judge. With some frequency, the breeders
administer testosterone in the form of drops during the training
period. Also with some frequency, shows are being conducted earlier,
starting at the end of October to the middle of November, obliging
the contestants to individually cage the birds earlier than was
stated above, even as early as mid-August to mid-September, which
could certainly alter the natural process of learning.
It is known that periodically, that is, once each
year during the molt, sometime in the months of summer and fall,
the canary stops singing with mastery in order to recuperate and
to renew his song; by winter the song can be the same as that before
the molt or, more or less, different from it. In relation to this
same point, there also exist a difference of opinion on its significance
such that those who use tutors say that if their birds do not modify
their songs in successive years it is because they have heard an
adult model of quality in their youths, while those who don't use
tutors attribute it to the idea that the song of their canaries
is a spontaneous expression of their genes, nothing learned apart
from their genetic endowment.
In the present article I seek to review and systematize
the empirical knowledge employed in the song learning of our canaries.
The method employed has been presented to breeders of different
tendencies, accredited by means of their wide experience, for their
input, and the written sources consulted were found in the MEDLINE
database of the US National Library of Medicine. This article will
unfold as follows: phases, hormonal control and learning, imitation
of adult models, and conclusions.
PHASES OF LEARNING
It would serve us well, before entering into the
polemics which follow, to review the existing studies on the form
in which canaries learn to sing their song with dexterity from birth
until the adult stage.
Birds sing in order to communicate with others,
establish breeding territory, and, in the case of males, to attract
their mates.
Since antiquity it has been recognized that certain birds possess
the capacity to imitate sounds; nevertheless, it was W. H. Torpes
who, in the 50's, demonstrated that songbirds exercise this capacity
habitually, and that they have the capacity to learn to sing in
a form similar to the way that humans learn to talk: imitating the
models provided by adults. He observed that the pinzones learned
to sing from adult models at a single stage of their lives, before
achieving their sexual maturity; afterwards they lost this capacity
to learn for good. This period in which learning could take place
he called the "critical period" in learning. It did not, however,
happen in the same way for canaries since these change their song
from year to year and are, thus, "time-unlimited" learners. Each
year they have their "critical period" of learning before the coming
of spring: during late autumn and winter.
The song of canaries evolves from birth until sexual
maturity, passing through various phases:
- The first sounds which a canary emits, between birth and complete
independence from his parents at the end of the fourth week, are
shrill cries that move his parents to feed him.
- The first rudimentary attempts at song begin in the fifth week
and last until the second month of life; these attempts are called
"subsong". They are of low volume and variable structure, and
are emitted when the bird is almost dozing: the bird is said to
be "reviewing his lessons" by breeders. They seem to represent
time periods and phases of vocal practice, from which eventually
originates the complete song repertoire which will be used in
communication.
- A more structured song, very near to adult song but retaining
much variability, is the area of "plastic song"; it lasts about
six months: from the beginning of the third month of life until
it achieves sexual maturity, at seven or eight months. As we will
see later, during the first half of the plastic song stage, the
size of the cerebral centers that control song increase only a
little, but, during the second half ( from the sixth to the eighth
month of life), there is a spectacular increase in the size of
the superior vocal center. In the last part of this phase, the
canary can already vocalize 90% of the syllables that he will
use as an adult.
- At the beginning of the first breeding season, the canary has
transformed the syllables produced into stereotypical sound and
expresses a "stable song" with a richness of concrete syllables
and following fixed and typical musical norms: the "locking of
the song" according to breeders. It does not seem easy to achieve
the consolidation of "stable song", if we consider the many months
of practice: the time of "plastic song".
- Without doubt, this song is not the song or definitive syllabic
repertoire which will be sung for the whole life of the canary.
Every year after the mating season, during the end of summer and
autumn, the bird looses his learned mastery of song execution
and this is exchanged for another period of instability of song,
just like the "plastic song" of the young. During this period
there will be dominant syllables which will be forgotten, while
at the same time new ones are incorporated into a new stable song,
which will be expressed in the following spring; thus, the adult
male canaries can unfold a repertoire of new syllables in their
songs. The transition from stable song to plastic and back again
to stable, is repeated annually in the adult canary.
HORMONAL CONTROL IN LEARNING
There are many environmental factors that can influence
song learning in canaries, like heard sounds, the light intensity
of the site they are in, the food eaten, the company of other canaries,
adults or young, and probably other unrecognized factors as well.
Moreover, this seasonal learning is controlled by hormonal balance;
the phases of new syllable acquisition are preceded by lower concentrations
of blood testosterone, the male sex hormone. Effectively, the canary's
song is characterized by the number of sounds or distinct syllables
it contains and by certain musical norms; when the canary is in
the plastic song phase, it may incorporate new syllables into its
song. This incorporation coincides with the augmentation of the
cerebral center which controls song, and is preceded by a fall in
blood testosterone levels; conversely when blood testosterone levels
are high the canary is found to be in the stable song phase, adding
few syllables to its song.
One may affirm, also, that the plastic song phase,
which goes from the beginning of the third to the end of the seventh
or eighth month of life, from approximately May to November, is
the "critical period" of learning among canaries, above all, during
the months of August, September, and October. During this time canaries
prepare by means of a natural capacity for learning for learning
syllables and musical norms, more so than at other months of the
year.
From that which was affirmed by the preceding paragraph,
one may deduce that if we shorten the duration of the critical period
of learning or plastic song phase, the canary would have less time
to learn new syllables and consequently develop a stable song with
a "poverty of syllables". If we give exogenous testosterone to canaries
during the period from the third to seventh month, approximately
from May to October, and raise the level in the blood to the level
reached in November, we can accelerate the sexual maturation, attaining
the stable song phase earlier, but this happens at the expense of
learning, with a shortened duration of the critical period. Also,
proceeding to the individual caging of the male birds when very
young, like the middle of August or middle of September, can accelerate
their sexual maturation, again shortening the critical period. These
two processes, giving exogenous testosterone and early individual
caging of the young, put one on a par with those breeders who are
obliged to present their canaries at song contests when quite young,
like the end of October or the beginning of November. But, in addition
to shortening the duration of the critical period, early caging
or addition of excess testosterone can counteract the capacity for
learning during the most productive months of this period which
are from August to October when the most syllables may be learned
by the canaries. As can be seen, the convocation of early song contests
can promote syllabic poverty in the songs of those canaries which
participate in them. Moreover, we must be aware that the early individual
caging of the young canaries creates a situation where learning
at this time is realized solitarily, while those caged at the normal
time, from mid-October to mid-November, have their learning period
enriched with the company of other male canaries; and in the same
way holding very young birds in the dark may alter the process of
learning qualitatively. Nevertheless, one may hypothesize that,
if one gives exogenous testosterone during the plastic song phase
(solely with the objective of restoring fallen levels of this hormone),
we will avoid possible deficits during the plastic song months and
perhaps stimulate the growth of the superior vocal center and the
nucleus of the archistriatum which will respond with a larger number
of neurons, causing a song with better syllabic richness without
pushing sexual maturation too far, shortening the duration of the
critical period.
*The nucleus of the archistriatum is part of the bird's song system
and will be looked at more closely in the second part of this article.
*The use of exogenous hormones seems to be a common practice in
some parts of the world, even though it remains controversial. So
long as shows which are staged later in the season become more widespread
in the US, perhaps this controversy can be avoided. The author makes
it clear that there is some considerable risk in using this artificial
aid (impoverished song, etc.), and a more natural period of song
development is to be preferred--trans.
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