December 3, Foxes are calling in the night to find mates and establish territory.

Performed by The Genetic Choir, Netherlands.
Commissioned and Produced by Public Works, Utrecht.

Marcus worked with the Genetic Choir to create a performance in Utrecht station to mark and celebrate the time of year when foxes are at their most vocal.

After researching fox vocalisations a repertoire of calls was chosen that the choir could mimic and improvise with. Four different choral movements were performed to the public, each exploring different calls and the voice dynamics within the choir. The audience were members of the public who were passing through the station, waiting for trains and using the shopping facilities.

Instruction notes for choir:

Remember it’s more than just an emotional language. Calls convey information about identity, location as well as motivation. Scent marking is main form of communication, vocalisation only used when instant communication is needed.

For animals which are social, yet spend a considerable amount of their time alone, vocalisations provide the only means of communicating instantly over long distances and in conditions of poor visibility, such as dense vegetation or at night. Since foxes are largely nocturnal and live in social groups, but on average only meet another fox twice a night, it is not surprising that they produce a wide variety of vocalisations.

Type 1: normal barks
This call starts abruptly, primarily into two constant frequency bands.
The call is often linked into other calls.
Within family group general warning and alarm, also territorial with explosive start.

Type 2: Yell barks
This call is similar to Type 1. It starts abruptly and is distinguished by the concentration of most energy in the central band and the gradual drop in frequency through the second half of the call.
Hostile, territorial towards a different group. Explosive start.

Type 3: Shrieks
Highly distinctive, with multiple frequency bands persisting for at least half the call. All are very similar. The energy of the call is more equal throughout.
Shrieks aren’t suited to aggression, gradual onset, long duration and highly complex frequencies make the caller easy to locate. majority of energy is at lower frequency and so will travel further than yell and normal barks. it was thought to be a vixen call to attract males, but males have been seen to use this call and outside mating season, so precise function unclear.

Type 4: whines
These are single note calls, often following, barks and yells. They are mostly ‘high whines’.
these have a single frequency containing nearly all the energy and two higher, fainter bands, possibly natural harmonics. The majority of the call was at this frequency, the beginning and end were frequency modulated, rising at the start and dropping at the end. The drop was often trilled. Contact calls:
Whimpers, much quieter, smoother sound than whine, ‘mew’
Contact seeking calls in close proximity around the breeding den. similar to murmuring cubs.

Type 5: ratchet calls
This type of call has been referred to as ‘keckern’, ‘clickerting’ or ‘gekkering’. Ratchet calls are most commonly a burst with a high variable number of components which can’t be individually identified. Each component is short and covers a wide range of frequencies. distribution of energy is uneven.
Ratchet calls are aggressive, threat call.

Type 6: staccato barks
call types 6 and 7 are the two main examples of long range multiple component barking.
Staccato is brief but distinct, the frequency range increased throughout the call. average of 3 components.
Staccato - simple, less energy, used to establish or maintain contact.

Type 7: wow-wow barks
multiple component barks. mostly within two clear frequency bands. This type of call tended to have more components than the staccato barks.
average of 6 components.
Wow-wow - conveys much information (complex frequencies), friendly use, adapted for distance. used within the group/family.

Type 8: yodel barks
These are much quieter/softer than staccato and wow-wow barks, single and linked components. Narrow frequency range. The energy of the call was invested in a frequency band which rose and fell rapidly, producing a yodel effect.

Type 9: growls
growls are highly distinctive, low frequency calls. average of 7 components. The energy was spread over a range of frequencies but within a small range. The last component of the call often dropped in frequency.
Growls are threat calls, for short distances (quiet), different body size creates different frequency so carrying information in ritualised aggression.

Type 10: coughs
Highly distinctive, quieter low frequency calls. range of frequencies with the last component often dropped in frequency.
Coughs are similar to growls in low frequency but are less harsh, commonly used near to the cubs, alerting danger and difficult to locate for predators.

Type 11: screams
Calls have little frequency deviation. energy was in a limited band, only one component.
screams are defensive sounds, carries little information, explosive, threat call.

Type 12: yell whines
noisy calls with clear frequency banding. the characteristic feature is during the highest energy the frequency changes, rising during the first third and falling with increased rapidity.
Yell whines, complexity carries identity information. also signifies intense submission.

notes from:
Structure and Function of red fox vocalisations
Nick Newton-Fisher
Bioaccoustics: the international journal of animal sound and its recording 1993 vol 5