Vocalizations of Red Slender Lorises (Loris tardigradus tardigradus) in Masmullah Proposed Forest Reserve, Sri Lanka

Abstract

During a radio-tracking study of L. t. tardigradus in Masmullah Proposed Forest Reserve, Sri Lanka, we recorded the animals' vocalizations and associated behaviors. The 1,720 calls we heard in the field fell into five call types: whistle (97.7%), chitter (2.0%), monosyllabic chitter (0.2%), "krik" and "zic" calls (0.1%). We provide a preliminary account of the contextual use of these vocalizations, with an emphasis on qualitative variation in the loud "whistle" call, by far the most common call type. Whistles vary greatly in their contextual use, structure, and usage frequency. Synchronous calls are uttered by mothers and infants in the context of infant parking and pick up. The average number of calls per hour was highest between 19:00 and 20:00 (1.9 calls/h) and lowest between 6:00 and 7:00 (<0.01 calls/h).