Asian Elephant Vocalizations

 Asian Elephant Vocalizations, Linguistic Data Consortium (LDC) catalog number LDC2010S05 and isbn 1-58563-557-X, consists of 57.5 hours of audio recordings of vocalizations by Asian Elephants (Elephas maximus) in the Uda Walawe National Park, Sri Lanka, of which 31.25 hours have been annotated. Voice recording field notes were made by Shermin de Silva and Ashoka Ranjeewa, of the Uda Walawe Elephant Research Project. The collection and annotation of the recordings was conducted and overseen by Shermin de Silva, through the University of Pennsylvania Department of Biology, and Institute for Research in Cognitive Science. The recordings primarily feature adult female, and juvenile elephants. Existing knowledge of acoustic communication in elephants is based mostly on African species (Loxodonta africana and Loxodonta cyclotis). There has been comparatively less study of communication in Asian elephants, primarily becaUse the habitat in which Asian elephants typically live makes them more difficult to study than African forest elephants. For other current elephant vocalization research, see ElephantVoices and the Cornell Lab of Ornithologys Elephant Listening Project.

This corpus is intended to enable researchers in acoustic communication to evaluate acoustic features and repertoire diversity of the recorded population. Of particular interest is whether there may be regional dialects that differ among Asian elephant populations in the wild and in captivity. A second interest is in whether structural commonalities exist between this and other species that shed light on underlying social and ecological factors shaping communication systems.

Methods

Study site and subjects

Uda Walawe National Park (UWNP), Sri Lanka, is located at latitude 630°14.0646N, longitude 80°5428.1268E, and an average altitude of 118 m above sea level. It occupies 308 km² and contains tall grassland, dense scrub, riparian forest, secondary forest, rivers and seasonal streams. It also contains several natural and man-made water sources and reservoirs with seasonal floodplains. There are two monsoons per calendar year, separated by dry seasons of variable length. Over 300 adult females have been individually identified in UWNP using characteristics of the ears, tail, and other natural markings (Moss, 1996).

Data collection

Data were collected from May, 2006 to December, 2007. Observations were performed by vehicle during park hours from 0600 to 1830 h. Most recordings of vocalizations were made using an Earthworks QTC50 microphone shock-mounted inside a Rycote Zeppelin windshield, via a Fostex FR-2 field recorder (24-bit sample size, sampling rate 48 kHz) connected to a 12 V lead acid battery. Recordings were initiated at the start of a call with a 10-s pre-record buffer so that the entire call was captured and loss of rare vocalizations minimized. This was made possible with the pre-record feature of the Fostex, which records continuously, but only saves the file with a 10-second lead once the record button is depressed. In order to minimize loss of low-frequency or potentially inaudible calls, recording was continued for at least three minutes following the end of vocalization events. During the first two months, hour-long recording sessions were also carried out opportunistically while in close proximity to a group. However, spectrograms showed that few vocalizations were captured therefore, this was discontinued.