What calls do redtail monkeys make? Part 1
Redtail monkeys make a variety of vocalizations throughout the day. I’ll explore these in two blog posts.
Distinct calls signal everything from (excuse the anthropomorphizing) “Watch out! An eagle overhead!” to “Please don’t chase me again!” to “Maybe we should start moving towards that fruiting tree we like.” The most comprehensive study of redtail monkey vocalizations was done in the mid-1960s by Peter Marler here in Kibale National Park, Uganda, as well as in another Ugandan forest called Budongo. Marina Cords also explored redtail monkey vocalizations in the context of predation at Kakamega Forest in Kenya in the late 1970s and early 1980s.
All spectrograms in these posts are from Marler (1973). All audio recordings are my own, recorded during 2015-2016 field seasons at Kanyawara site in Kibale National Park.
PHRASED GRUNT: the quietest and most common call that Marler heard in the 1960s and that I hear when I follow redtail monkey groups today. This short series of soft grunts is a contact call between group members and often occurs when the group is about to or has started moving to the next feeding tree.
Figure 7 from Marler (1973): phrased grunts of redtail monkeys (R1-R4). R4 is example of "high phrased grunt." R1-R3 Kibale, R4 Budongo. Scales: frequency, 500Hz; time, 0.5 seconds.
CHIRP: a common call made by adult females and subadults in multiple alarm contexts. I’ve heard redtail individuals chirp repeatedly, for example, when chimpanzees or eagles are nearby and/or vocalizing, but also when startled by a large tree branch breaking, a large bird like the great blue turaco flying over or when baboons vocalize loudly. Redtail monkey adult females also chirp during aggressive encounters with other redtail monkey groups.
Figure 8 from Marler (1973): chirp calls by redtail monkeys (r1-r12). r10 and r11 Kibale, others Budongo.
Click HERE to listen to multiple vocalizations made during an aggressive intergroup encounter in 2015 between two redtail monkey groups in Kibale. The most common vocalization during this encounter is chirping, though you will also notice scream- and growl-like vocalizations.
Pictured below is an adult female mid-chirp during (a different) 2015 intergroup encounter between redtail monkey groups in Kibale:
TRILL: a high-pitched call usually with pitch descending. Marler (1973) suggests that the trill is a submissive call made by subadults to adults. Though Marler only observed subadults trilling, I’ve also observed adult females making this vocalization, so I’m unclear on the function of this call.
Figure 9 from Marler (1973): trills by subadult and juvenile redtail monkeys in Budongo, with insect (Orthoptera) sounds in the background.
References:
Cords, M. (1987). Mixed-species association of Cercopithecus monkeys in the Kakamega Forest, Kenya, by Marina Cords. University of California Publications in Zoology, 1-117.
Marler, P. (1973). A Comparison of Vocalizations of Red‐tailed Monkeys and Blue Monkeys, Cercopithecus ascanius and C. mitis, in Uganda. Zeitschrift für Tierpsychologie, 33(3‐4), 223-247.
