Experiment Details: Acoustic variations in male Diana monkey alarm calls / Project: Olive colobus grammar

Quentin Gallot

Department of comparative cognition, Institute of Biology, University of Neuchâtel

quentin.gallot@unine.ch

Not provided

Klaus Zuberbühler klaus.zuberbuehler@unine.ch

Conceptualization, Data curation, Formal analysis, Investigation, Methodology

Léo Perrier

Yes

Acoustic variations in male Diana monkey alarm calls / Project: Olive colobus grammar

The primary aim was to study the vocal communication system of the Olive colobus monkey and the combinatorial rules involved in the production of call sequences. Since this species is almost always found in association with Diana monkeys, we are now exploring, as a side project, the impact of experimentally induced danger types on the alarm call production of male Diana monkeys.

The study was conducted in the Taï National Park (Ivory Coast) about 20 km south-east of the town of Taï in an approximately 70 km2 area surrounding the ‘Center de Recherche en Ecologie’.

We analyzed three different datasets, collected over two long study periods (dataset 1: 1994–1999, playback experiments; dataset 2: 2021–2022, playback experiments; dataset 3: 2022, predator visual model experiments).

This study used playback and predator model experiments to investigate the vocal responses of unhabituated Olive colobus monkeys within mixed-species groups. Groups were exposed to predator vocalizations, including leopard growls and eagle shrieks, as well as chimpanzee pant-hoots and falling tree sounds. To prevent pseudo-replication, multiple versions of each stimulus were used, ensuring that each group responded only once per version. Sounds were broadcast using a loudspeaker, placed either near the ground or in the canopy, with volume adjusted to mimic natural conditions. In addition to acoustic stimuli, predator model experiments were conducted using visual models. These included a leopard model, where an experimenter covered himself with leopard-patterned fabric, and a crowned eagle model, featuring a life-size 3D-printed and hand-painted eagle presented behind a camouflage net. Both models were animated for realism, remaining in sight for a maximum of one minute before withdrawal, and two different versions of each were used to avoid pseudo-replication. Groups were located by tracking mixed-species calls, such as those of Diana monkeys or red colobus monkeys, and were observed from a distance of 25–75 meters for at least 15 minutes before playback initiation. To prevent retesting, no group was tested within one kilometer of a previous experiment for at least one week, considering the Olive colobus home range size of approximately 0.56 km². This methodological approach ensured controlled and ecologically relevant testing of Olive colobus vocal responses to various stimuli. Presence of Diana monkeys were noted during each trial.

We played back sounds from a Samsung Galaxy XCover 4 (model SM-G390F, with media sound on maximum volume) connected to a Nagra Kudelski DSM-monitor loudspeaker (frequency response 60– 15,000Hz ± 4 dB), from an iPhone 5S (iOS 12.5.4) connected to an Alpha speaker (AER, The Acoustic People: frequency range 60–18,000 Hz), or from a Sony WMD6C Professional Recorder connected to a Nagra Kudelski DSM-monitor loudspeaker. We recorded vocal responses with Sony WMD6C or TCM5000EV recorders and Sennheiser ME88 or ME67 directional microphones (frequency response, 40–20,000Hz ± 2.5 dB). We also recorded responses with a Marantz PMD 661 MKII recorder and a Sennheiser MKH 416 P48 directional microphone (frequency response, 40–20,000Hz ± 2.5 dB). 1994–99 recordings were digitized with Audacity software v2.1.0 (44.1 kHz sampling rate, 16 bits accuracy, WAV format) using TASCAM CD-A500 and Technics M280 devices.

https://doi.org/10.1016/j.isci.2024.111172; https://doi.org/10.60544/nd6p-dk04

Cercopithecus diana

Procolobus verus, Cercopithecus diana, Cercopithecus campbelli, Cercopithecus petaurista, Colobus polykomos, Procolobus badius, Cercocebus atys, Cercopithecus nictitans

rain, human speech, unknown insect and songbird vocalizations

Diana monkeys measure 40 to 55 cm in body length, with a tail of uniform diameter extending 50 to 75 cm. Adults typically weigh between 4 and 7 kg. Their fur is primarily black or dark grey, with distinctive white markings on the throat, browband, ruff, beard, and underarms. A white stripe runs down their thighs, while their lower back and the backs of their thighs are chestnut-colored. Their fur, except for the softer browband, ruff, beard, and limb fringes, is coarse and dense.

https://doi.org/10.1006/anbe.1996.0334

The species is endemic to West African rainforests.

In Diana monkey groups, typically only one adult male vocalizes alarm calls, although individuals from neighboring groups may also be heard. As this species was not the primary focus during data collection, neither the caller’s identity nor the group’s size was recorded, making it impossible to estimate the number of vocally active female Diana monkeys.

I cannot do this

Yes

https://drive.google.com/open?id=1hXdzWcJulNaWss5zGVDrdbA23GkmVNHn

I need assistance from the VoCallBase team for this step, as they already have access to the dataset. Additionally, some recordings may not contain male Diana monkey alarm calls, and there is no existing data to filter out these files before beginning the annotation process.