This year I have been taking notice of the nocturnal songsters in our area (see Nightingale observations (May 1 – 2, 2024) – singing perch preferences; Nightingale observations (May 4, 2024) – song as a tool to regulate spatial distribution; Nightingale observation (May 19, 2024) – reduced singing activity in warm night weather? but also Grasshopper warblers observations (mid-May, 2024) – does this species, too, sing at night?).
Typically, the night scene used to be dominated by nightingales which are highly adapted to singing even when it is yet quite cold (at night, even barely above zero).
As the second half of May was as warm as June or even July (especially, concerning night temperatures), I was astonished to discover other nocturnal singers who joined company with the nightingales keeping up with the renowned performers all through the night (I got to listen to their song from ca. 1.30 am to dawn and the grasshopper warblers, in particular, did not decrease the intensity of their vocalizations at any hour if perhaps taking very short breaks to grab a snack).
As I was wondering about these ‘background vocals’ (nightingales were still rather dominant as they could be heard from a great distance while the warblers were impressive at a closer range), I realized that there might be some similarities to how these species (which routinely sing at night such as nightingales or which can sing at night if it is profitable such as warblers) produce sound.
Perhaps their morphology and sound production mechanism is different from other species enabling nightingales, warblers but also thrushes to sing at night when it is colder.
Such considerations also led me to contemplate traditional music (sometimes referred to as world music) by people in cold regions vs. warm regions.
Nightingales and warblers seem to produce many sounds that are ‘throaty’.
‘Throaty’ is not a term which is held in high esteem among vocalists; however, I am using it in the sense of ‘vibrating in the throat’ (similarly to, for example, Mongolian throat singers).
Not all vocalizations by nightingales are ‘throaty’ in this sense but, according to my humble hearing estimates, they might be produced through resonance that is achieved in the head cavity rather than the body cavity.
Namely, it seems that the nocturnal songsters might be using throat and head as the main resonant/vibrational apparatus.
The throat sounds are clearly perceived as the ‘chirping’ but the head sounds could be those of a very high pitch (such as observed in nightingale songs).
Meanwhile, it is possible that other bird species (and perhaps bird species that only reside in warmer regions such as tropics) do not rely on the resonance produced in the upper parts of the body but rather engage the lower body cavity where many important organs (e.g., heart, lungs, gut etc.) are located.
The difference could bear impact on the extent to which the cold air enters the body and the duration of its ‘stay’.
Brain is the only organ which could suffer damage due to exposure in the head cavity while many other crucial organs could be harmed in the main body cavity.
Additionally, it might be easier to evolve adaptations that allow to protect the brain alone vs. adaptations to protect all the rest of the organs.
Coincidentally, for example, nightingales have a very complex singing pattern which, to me, sounds almost mathematical and ‘coded’.
Perhaps nightingales do not sing out of ‘gut’ but out of ‘brain’ (quite literally), i.e., the composition of their vocalizations might be based not on metabolic processes that occur in the whole body (physiological pathways) but rather on cognitive processes that occur in the brain.
By engaging the brain as the organizer of the vocalization pattern, the nightingales might be, firstly, excluding the organs that must be protected (and perhaps lowering the general metabolic costs of the vocalization) and, secondly, engaging the brain actively which could heat it up reducing the impact of the cold in the head cavity and preventing damage to itself.
As a result, the song by the nightingales could be more ‘deliberated’ than songs by other bird species due to the predominant involvement of the brain regulatory pathways.
This could also lead to differences in the species’ behaviour (due to increased complexity of the brain) and perhaps some inability to ‘fit in’ with the general dawn and dusk chorus.
Meanwhile, warblers might mostly rely on the throat vibrations.
Species that produce sound mainly in the throat area, could have better control over the air flows that pass into the body cavity and out of it.
The vibration itself is rather intense and might provide additional heat transduction.
Vibrations themselves do not appear to be producing much heat but they are involved in dispersion of heat.
As a result, some metabolic costs might be reduced if the warblers (as well as nightingales which often use ‘thrills’) can use the mechanical vibrations to conduct the heat from heat-producing organs instead of only relying on blood circulation.
However, heat might be produced from friction and perhaps some heat is generated (and thence distributed) through the interaction between vocal cords and perhaps as the sound waves impact upon internal structures (thence, throat singers such as warblers might even produce some heat).
I am, at this stage of my education, not very knowledgeable of world music as I have been focusing on classical music thus far.
However, my superficial insight suggests that musical traditions in the north involve much ‘humming’ as well as ‘throat-singing’.
Many of the songs are quite ‘low and thundering’ (produced in the body cavity but not released in the same manner as, for example, flamenco singers release the sound) seemingly vibrating the ‘deep core’ of the body cavity and using throat as an important conduit which determines the extent of the release (the sound is not let out fully at once but in a regulated, portioned manner which could reduce the total number of deep breaths taken).
Additionally, there are high-pitched and sharp-pitched sounds (similar to those produced by nightingales or thrushes) that resonate in the head and that have given rise also to many classical music vocalizations which have largely originated in colder countries.
Much of the ‘northern singing’ is rather head-bound and brain-organized (focused on such cognitive controls as lyrics and non-improvized repetition of patterns as well as very fine-tuned harmonizing between separate singers, i.e., choir singing whereby everyone has their own tune that blends into one melody which I believe is the case with nightingales, as well, because their song sounds much more prominent and advanced when regarded as a product of all the nearby nightingales singing together).
Meanwhile, ‘southern singing’ is often improvised (including not relying on lyrics or using the lyrics only as a guiding motif), involves a full, unrestrained release of the sound without attempting to regulate it in the throat.
Songs are often accompanied by dances and the vibration is not contained somewhere deep in the body cavity but rather takes over the entire body encouraging for the limbs to move along.
There are fewer sounds that are resonated in the throat or head alone and most sound seems to travel all through the body (as if the body was not compartmentalized but rather a united, open-channel instrument).
Perhaps such singing allows not as much to disperse the heat along important organs (that are usually deeper in the body cavity) but to dispense of the heat (as the singing is performed in very warm or even hot climatic conditions) by vibrating it right out of the body.
I do not wish to claim that ‘body singing’ (the warm-vocalizing species style) is necessarily non-inclusive of brain and cognition, not at all.
But it is possible that the brain is involved a bit differently, e.g., through producing hormonal reactions and emotional responses.
Additionally, the ‘northern song’ could be more rigid and subject to custom because it must follow an organized, learned pattern.
Meanwhile, the ‘southern song’ might be better attuned to ‘the present moment’ because it involves the entire physiology and the body might assist in producing sounds that are compatible with the current environmental stimuli (environmental conditions that occur during singing and that elicit responses in the body which can react at once because the music does not have to go through the brain first).
Additionally, my observations regarding the springtime nocturnal singers suggest that those are species which sing in leafy shrubs that can keep vocalizing into colder hours (although nightingales also vocalize near rivers where sound travels further and becomes amplified but where vapours can create colder microclimatic conditions).
Leafy shrubs provide some insulation and also shelter against predators.
Other species that sing in more open conditions (e.g., trees many of which have not budded into leaf yet during the first courtship attempt in the northern regions) might not be as protected from the weather.
As the vocalization is linked with nesting/breeding behaviour, the birds cannot really choose where they sing as freely and their evolved niche could additionally determine whether they have the potential of joining in with the nocturnal performers.
Humans might not have been as restricted in their singing habitat as birds are.
Still, there could be differences between singing traditions that have originated in cold and open situations vs. cold and forested regions vs. hot and open vs. hot and forested regions.
This could have social relevance.
For example, warblers are capable of ‘pushing their sound’ through the canopy (the throaty warbling, chirping) but their song does not travel very far and is best heard nearby (from < 5 metres).
Accordingly, they can only attract mates who have also already settled in the area.
Meanwhile, nightingales, with their head resonance and their preference for shrubs (insulation, cover) near rivers (sound conductance) can achieve dispersion of the sound over at least a kilometre and they could easily attract mates which are merely flying over (many bird species achieve their migratory flights during night).
For birds, the result could be that of a higher degree or interpopulation mingling in nightingales vs. breeding within the local flock in warblers.
Similarly, nightingales might have a more individually selected nesting sites (and, therefore, a more individualized mate selection) because their singing perch considerations are far more complex and perhaps, from the sound produced (extent of suppression from leaves + extent of soundwave dispersal by water) the prospective mates could even determine quite specifically what type of a breeding habitat/patch the male has chosen.
In human societies, if the climate and the habitat determines the singing physiology and cognition, patterns might arise, as well, whereby some cultures might prefer to sing in small, intimate groups (that can, coincidentally, flock under a roof and that can learn the same lyrics and vocal patterns) while other cultures might have community singing events.
Such differences could even arise on a seasonal basis having divergent singing traditions during cold months (winter) and warm months (summer).
I believe these issues could result in a very interesting research collaboration between anthropologists and biologists.
Notes by Ieva 