This is one of the main reasons, for me, that having chooks is interesting. The following is excerpted from N. Collia's, The Spectrographic Analysis of the Vocalizations of the Red Jungle Fowl. His research was conducted on the flocks that used to roam in the San Diego Zoo. One of our members is still breeding offspring of the dispersed flock (guess chooks didn't grab the crowd). The complete paper is available here:
http://elibrary.unm.edu/sora/Condor/files/issues/v089n03/p0510-p0524.pdf If it won't download completely, view it in HTML format, copy and paste ALL and reformat in a Word (or whatever) document. It is the seminal work on `ChookYap'.
I found this as well when running down info on the intergradiation of signals and vocalizations that are flock specific. I know there is some learning going on, but research is somewhat scarce and I'm not about to start ablating ol' Roodawg's brain in order to observe the alteration in vocal signalling...
http://www.applied-ethology.org/isaemeetings_files/1991 ISAE in Edinburgh, Scotland.pdf
The abstract is on page 90: Pre-dustbathing vocalizations of hens as an indicator of a "need" : The "'Gakeln" (I think it sounds like: `wrraaaakn' call is one we know well. There are a couple hens waiting to be `unleashed' for the evening ranging right now and they are complaining bitterly. Ours also use this call to let us know that they want the coop door opened NOW. They have plenty of opportunity to dustbath in the run, they are using the "Galkeln" to express another frustration... (better let `em out). Ours also growl (staring down each other /territory-tidbit priority; in unison ``predator approaching' - more than vague `uncertainty'. `Chortling' (lilting somewhat `songish') in unison only heard, over monitor, within 5 minutes of the start of rain (some `jungle memory'?).
From Collias (first link):
"1. Rising vs. falling pitch (chicks): Pleasure vs. distress
2. Clear tones vs. white noise (hiss): Attract vs. repel
3. Low vs. high pitched notes: Attract vs. repel
4. Brief vs. long notes: Attract vs. repel
5. Soft vs. loud notes: Attract vs. repel
6. Slow to fast repetition rate of notes: Increased stimulus intensity
7. Regular to irregular repetition of notes: Increased stimulus intensity
8. Gradual or abrupt onset of call: Set to respond vs. startle
9. Steady vs. wavering tones: Secure vs. disturbed
10. Consistent vs. inconsistent number of notes: Stereotyped vs. flexibility
"The essential function of antithesis in Darwins sense is to reduce ambiguity in signalling. This is especially clear for the first five pairs, inwhich the first member of each pair reflects what could be considered a positive or pleasure state in the signaler, the second member a negative or unpleasant state. Thus, rising vs. falling pitch in a chick call is associated with either a state of well-being (pleasure) or conversely with some objectively specified stressful condition (distress). Some objective, experimental evidence for the antithetical effects of Pairs 2 to 5 has been given for the responses of domestic chicks to systematic variations in stimuli (Collias and Joos 1953). These pairs are antithetical in that the first member of each pair tends to induce approach, while the second is more likely to stimulate avoidance by a chick."
"SIZE OF VOCAL REPERTOIRE OF THE RED JUNGLEFOWL
Calls can be identified to a considerable extent by the general situation in which they are given and by their sonograms. Because of the existence of graded signals and of intermediate stimulus situations it is not possible to specify any absolute limit to the size of the vocal repertoire. However, in practice, specific calls recur frequently and characteristically in certain situations, enabling one to give a rough but fairly accurate estimate of the size of the vocal repertoire.
Based on the above criteria, I feel that I can recognize about 24 different calls given by the Red Junglefowl. Calls of chicks include: (1) distress cries, (2) pleasure notes, (3) fear trill, (4) pleasure trill, and (5) a fear note, which is a sharp cry given by a chick when it is abruptly seized. Guyomarch (1962, 1966) who has described variations in the calls of small chicks in some detail gives a sonogram of this last call (1962:294). Additional calls, given by adult Red Junglefowl, include: (6) clucking by hens, (7 and 8) food calls of two types, (9) purring, (10) courtship call (two parts) of cock given while wing-fluttering to hen, (11) contentment calls, (12) contact grunts, (13) singing, (14) whine or moan of disturbance or frustration, (15) alerting call, (16) startled squawk when pecked, (17) distress squawks when captured and held, (18) alarm cackling (two parts) to ground predator, (19) alarm scream to flying predator, (20) loud defensive threat to flying predator, (21) hiss by hen on nest, (22) protest growl by broody hen when disturbed, (23) threat calls of low intensity by cock or hen, and (24) crowing by the cock.
In the domestic fowl, which has essentially the same vocal repertoire as the Red Junglefowl, Baeumer (1962) who has given the most comprehensive verbal account of the calls described 30 different calls, based on close observation over many years. Konishi (1963) who had access to Baeumers tape-recordings, made sonograms of many of these calls. In general, the calls recognized by Baeumer and by myself appear to be about the same. The probable reasons for the difference between his count of 30 and mine of 24 can often be specified: (a) he classifies as two signals (his 6 and 7) what I have called two parts of a compound call in the case of alarm cackling to a ground predator, the preliminary cut-cut notes and the loud kaah!; (b) what I have at times labeled the same call in different situations he apparently labels as different calls in the different situations: the distress cries of a hen when seized (Baeumers 10, BlO) and or when held (Bl 1); or the protest growl of a broody hen to avoid copulation (B13), to defend her nest (B14), and to defend her chicks (B16); or clucking by a hen when leading chicks (B18) and when brooding chicks (B19), admittedly variants of the same call; and (c) labeling different intensities of onecall as different calls, such as short (B25) or long (B26) threat notes of a hen. Baeumer recognizes different categories (B20, B21) of the alarm cry to a flying object, which Konishi (1963) has identified as different intensities of the same call especially as indicated by length of the call. I also suggesat n additional category( no. 20 on my list), the loud, relatively low-pitched defensive threat (roar) to a flying predator that is departing or is relatively nonthreatening. In general, as with lumpers and splitters in taxonomy, the decision whether to distinguish one or two similar calls that sometimes intergrade, can be rather arbitrary. The important thing is not the absolute size of the vocal repertoire that is estimated, but rather that the physical characteristics of each call and the situations under which it is given be accurately and adequately described so that the same call when described by different observers can be recognized as such."
(sorry for long post, but this is the gist of the `interpreter's course for your reference)
ed: link repair - formatting)
