BIRDS
BIRDS IDENTIFICATION BY THE
VOICE *
I- VOCALIZATION: FUNCTION AND IMPORTANCE
Birds, with rare exceptions, have an important characteristic, that is the power of vocalizing. The responsible organ for vocalization is the siring, a kind of complex organ that is part of the breath system.
The vocalization as one of the most important ways of birds’ expression and communication appears as singing or calling. The singing is a series of tunes, generally from more than a kind, which is given out in succession and related to each other, forming a tone sequence well recognized, and has complex characteristics of rhythm and modulation, which differ them among the species. Afterwards, the singing is basically under control of sexual hormones, are related to the time of reproduction, as to establishing and defending the territory too, and also with the maintenance of the couple (male or female).
The call note is mainly constituted by monosyllabics’ or disyllabics’ tones, never more than four or five tones, and appears in the coordination of the young’s behavior, of the band and of the family during the maintenance activities, as feeding, migration, band and answer for the predators.
In closed places, as the interior of forests, the vocalization assumes bigger importance, because of the difficulties of seeing among the individuals of the same specie.
At the countryside, despite the less importance of vocalization, it doesn’t lose its value, because in the open area where are grama-grass the birds also are “covered” in some way by the creeping branches, and the big port trees are little, so that’s the why for the necessity of the voice for communication, as we can see for example at Anthus lutescens, that needs to do vertical flights, singing, for being located by the female and/or demarcate the territory.
It also has to be observed that the birds’ vocalization was of a big importance to the primitive man, who used it for calling the bird, and, afterwards knocking it down.II- STUDY’S PURPOSE
Forward the knowing of these ways of vocal expression, man can better improve and develop the birds’ fauna study of a certain place, because will be well prepared for a better identification of the species.
The birds’ survey or registration for a lot of purposes, as for making richer the museums’ collections, elaborating scientific studies, mere delight, or birds’ study by a simple observer or amateur ornithologist. When the study is done for a museum or for the developing of a scientific work, normally is knocked down individuals that will be identified after, through the literature’s comparison or helped by other collections. But, not also this way of identification is possible, because beyond the law prohibits wild animals’ hunting, also the preparation of the skins (stuff with straw), by its difficulty, is not reached by many people. Afterwards, is not justified the knocking down of known and easy identifying birds, just for having a collection with none scientific value.
In not having the catch of the animal for knocking down or by the use of fog’s net, the student may identify the bird by the simple field’s observation. In this, observation is more complicated, because the bird generally doesn’t stop, skipping or jumping from a side to the other, making the identification difficult.
For identifying a bird in the field is needed a special attention and observation of important details as the colorful or plumage’s detail, posture in flightiness and perching, singing and also the size. Having these written data, the interested person will look for in a museum or in the literature.
Normally the kind of vegetation and environment are used for helping in this work, because the bird is tied to a certain habitat. But one of the most important aspects for field’s identification is the vocalization, so that’s the why it’s necessary to the observer knowing the birds’ voices.
The good observer can register the presence of a certain bird in a place, without having been seeing it, just needing knowing its voice for this. Obviously that in a survey with scientific character, just must be registered the presence of a certain specie if there is absolutely right of its occurrence, mainly if it were recognized just by the voice.
When the survey is done just for amateurs’ studies, the observations can be done by binnacles and recorders, without bigger preoccupation, but a bird never must be registered if there isn’t sure about its identification.III- STUDY’S METHOD BY THE VOCALIZATION
For studying the vocalization of the birds it must be started with the observation of the study’s place, surveying the biggest quantity of data about vegetation, altitude and climate, for a perfect description of the habitat and after must be examined a list of possible species that occur in the place of study. With these data, the observer will do the direct observations of the local bird’s fauna, using a binnacle, a field’s notebook and especially a portable recorder.
The birds that are soon visually identified must be registered in the field’s notebook and the ones that cause doubts must be described and/or drown, taping its vocalization for being used as a caller, because a lot of birds are territorial and answer to the calling taped from them, making easier its visualization, beyond the process called “play back”. The registration of the birds’ vocalization, beyond the practical utility said, serves for an after observation.
The recording can be done by any kind of portable recorder, being the tape recorders the easier to find and to use, but there are in the market the digital recorders, known as DAT, high definition and technology, that may be used with directional microphone, but are expensive and difficult for importation.
A lot of professional ornithologists like and use the roll’s recorders, united to parables, being the Nagara and Uher the better ones, but its utilization is also difficult, because of its weigh and size and also high price. But, these last instruments, beyond the restriction said, also the difficulty of its using into the wood is bigger, by the little versatility in the use of the parable, in the way that is better using a tape recorder or DAT with directional microphone, becoming the work more practical and easier. Now there are the mini-cds recorders, with high definition.
The recording can also be done using camcorders, because the reception of these equipment have good definition, and after can be done a copy in a tape, for better using and archive. The vantage of recording vocalization with a video camera is that, beyond the sound, it gets the image of the habitat of the recorded specie, and being possible to do a video tape of vocalization, being also as a help in the identification of the species. So, with the written data about the habitat and a possible description of the bird, and still with its voice recorded, the observer will have big chance of success in the identification of a big number of species.
The student can also organize a voice bank, separating the species by family, what will help a lot in the identification, being good for comparisons and studies, and it also incentives the observer to get more and more vocalizations’ registers of the species, being a big challenge.
Through the advent and improvement of electrical-magnetic instruments, scientists have been getting great results with the elaboration of sonogram, that is the reproduction of the sound in a paper, fixing the characters of the sound’s manifestation, permitting the species’ identification, inclusive with similar voices.
But, this system is out of reach for the bigger number of students, certainly of almost all the amateurs’ ornithologists and observers, but this doesn’t obstruct their study, because also with modest means as the use of a simple tape recorder is possible to have good results, despite the limited quality of the equipment, which capacity may become better joining a directional microphone, if there is an enter for it.IV- VOICES DIVERSITY
The species are joined in families, by the common characteristics, but by its “voice timbre” or by its type or characteristic it’s possible to conclude many times, immediately, which family belongs to the studied individual, as for example the Psittacidae (macaws, parrots and parakeets), vocalizes high and strident in most times, the Picidae (woodpeckers) are yellers, the Emberizidae are melodious etc.
In the other hand, another birds have a grave voice, as Ramphastos toco (Toco Toucan). The hummingbirds have a sharp voice, but too low and repetitive. Birds as the Herpetotheres cachinnans (Laughing Falcon) have big capacity to vocalize, repeating its singing for some minutes, mainly in the twilight. Another ones have short and quickly vocalization, as some Dendrocolaptideos, that give a yell or two, and some other have a long and monotonous sing, as the Chamaeza campanisona (Short-tailed Antthrush).
There are birds with day’s habits, twilighters and the nighters ones. About the day’s birds, the identification by the voice is not so difficult, because are easier for seeing, but the twilighters birds and also the nighters, the importance of the knowing of the vocalization grows considerable, because almost all the times is impossible for seeing them, in the way that its occurrence practically just can be registered by the voice they give out. So the importance of the knowing of the vocalization, but the situation is complicated when all the ways of vocalization of the species are known.
As said before, in birds the vocalization means a lot of necessities and situations, being of big variety for the same specie, given as example the dozen of different sings in Guira guira (Guira Cuckoo) and also Thryothorus longirostris (Long-billed Wren).
It’s also important to observe that exists the dialects that are vocalization’s variety of birds of the same specie by the different region, being the sing way of loneliness of the specie, in a way that making the study more perfect, the number of registers may grow a lot, because just a specie can have a dozen or more dialects.V- CONCLUSION
For all these, it’s seen that the birds’ vocalization study for its identification is almost without an end. So, it is concluded that this study provides and is of big importance in the identification of species, mainly in field, where the bird, a lot of times, is not seen but just heard its singing or calling.
Besides, this identification method is reached by everyone who is interested in the birds’ fauna, since a simple amateur up to a professional ornithologist.
A pleasant method for an exciting activity.* Summary of a conference uttered by Antônio Silveira R. dos Santos, in the Zoology’s Amphitheater of São Paulo’s University (USP- Brazil), in 12/03/1994, for Ornithologicals’ Studies Center CEO-, and object of publication in the Report n° 10 of this entity.