Bioacoustics research at Issa centred initially on chimpanzee long calls – pant hoots – and their role in chimpanzee nest site selection and mediating party reunions. Chimpanzees in savanna habitats are known to form small daily parties and aggregate in larger groups at night. Additionally, population density estimates are significantly smaller and home ranges are significantly larger than those of forested communities. Given their fission-fusion social system, how chimpanzees coordinate reunions remains poorly understood.

While much is known about the function of pant hoots, the species specific chimpanzee long call, few researchers have been able to situate this behaviour in a socioecological context given the necessity to observe both caller and listener simultaneously – often a logistic challenge. To overcome this, I deployed Cornell University’s Autonomous Recording Units (ARUs) in 2006 to pilot test this method at Ugalla. A historically successful approach with marine mammals and birds, acoustic localization has not yet been widely used by primatologists.

The 2006 pilot deployment of 3 ARUs successfully recorded (from >2km) and localized (from almost 1km) playback and wild chimpanzee pant hoots and screams from Ugalla, demonstrating the potential for this method. Additionally, numerous species of bird, six species of primate, bushbuck, and puddle frogs were among other species recorded by ARUs, revealing the potential of this method as an instrument to conduct bioacoustic surveys in remote areas that are difficult to reach on foot. Since then, with the help of Bill Sallee of Santee, California, and John Hildebrand and team at the Scripps Institute for Oceanography in La Jolla, I have developed a new, solar-powered system that records continuously and relays sounds in real-time to a central receiver. This system was deployed (2009-2010) at Issa where at one point 20 solar powered acoustic transmission units (SPATUs) were recording in an area of about 24 square kilometers.

This system was later improved with the help of Paul Robertson of University of Cambridge, and was an integral component of the 2011-2012 survey of the Greater Mahale Ecosystem. Those acoustic data are still under analysis, but some sounds have been identified (thanks to David Moyer), and are below for your listening pleasure.

In 2014, research continued into primate long-distance communication at Issa, with efforts focused on characterizing the heterogeneous sound environment within which Ugalla chimpanzees and sympatric wildlife vocalise. Specifically, Wildlife Acoustics Song Meter 3 acoustic recorders (left) are being deployed to monitor the calling behaviour of Issa’s loud calling fauna. Lucy Tibble (right), then an undergraduate student at the University of Cambridge, conducted her undergraduate dissertation research on galago (Otolemur crassicaudatus) vocalization behaviour, walking line transects during the Issa nights to compare vocal and visual encounter rates. Results comprised her honours thesis, and were presented at both Spring 2015 PSGB meeting and also the 2016 IPS meeting in Chicago.

Research into animal sounds was expanded to red-tailed monkeys in June 2016, when Tifany Volle from LJMU began her undergraduate dissertation work. Tifany is studying the vocal repertoire of the focal troop, specifically how and when calls are used in various behavioural contexts. Listen below to red-tailed monkey chirping, for example!

Male B

Issa red-tailed monkey, adult male (E. McLester)

TIfany Volle - recording

Tifany Volle of LJMU recording red-tailed monkey vocalizations (July 2016)



Simon Hoggett surveying wild chimpanzees in Cameroon (September 2016)

In 2016, UPP collaborated with Osiris Doumbe of Bristol Zoo in a survey of chimpanzees in north-west Cameroon. UPP contributed SM3 recording units, whilst Osiris coordinated the survey work. Read about their preliminary results here.



It’s not just acoustic units that document vocalizations, though. A July (2014) camera trap file provided the below video and sound clip:

Waveform and spectrogram captured from the above video

Scientific Name Common Name
Dendrohyrax arboreus Bush hyrax
Cuculus clamosus Black Cuckoo
Francolinus hildebrandti Hildebrandt’s Francolin
 Paraxerus sp. Bush (rope) squirrel