A highly unusual, idiosyncratic and learned call that sounds like a distant lorry, foghorn or didgeridoo with a fundamental frequency of 50 Hz (similar to trucks) and highly variable in duration (range: 685 ms to almost 15 seconds). This sound is unlike any call in the normal repertoire of African elephants.
In an article entitled, Elephants are capable of vocal learning, published in the journal, Nature, in 2005, Poole and her colleagues reported the imitations of truck sounds by a ten-year-old adolescent female African elephant, Malaika, who was living in a semi-captive group of orphaned elephants in Tsavo, Kenya. Trucks were sometimes audible from Malaika's night stockade which was situated some three kilometers from the Nairobi-Mombasa highway. Poole and her colleagues were able to show, statistically, that the elephant was imitating the sounds of distant trucks. Since the publication of the 2005 paper additional elephants in the small Tsavo group of orphans have learned to produce the same sound. Click to (download/open Poole et al 2005, Elephants are capable of vocal learning. NATURE|VOL 434 |24 MARCH 2005. (.pdf 296kb).
References: Poole et al 2005; Poole 2011. (Full reference list)
This behavior occurs in the following context(s): Novel & Idiosyncratic