Physical characteristics, categories and functions of song in the Indian Robin Saxicoloides fulicata (Aves: Muscicapidae)

Abstract

The physical characteristics and biological significance of song in the endemic Indian Robin Saxicoloides fulicata are described. Songs are discrete and composed of strophes (structural units) with frequency ranging from 1.03 to 8.00 kHz, preceded and followed by temporal intervals from 0.21 to 21.25 sec. Occasional, monosyllabic whistles are also identified. In a song bout usually the same type of strophe is repeated several times in a stereotyped manner with minor structural variations of elements before switching to another type of strophe. Most strophes are composed of two to five elements, having both simple and complex structure. Two categories of songs have been identified on the basis of their acoustical features and context of production. Type-A songs are simple, stereotyped, spontaneous and common, while type-B songs are rare, female-oriented and more complex than type-A. Song is used in both inter- and intra-sexual contexts. It seems that type-A songs are driven by male-male competition for territory and mates. Males also shorten the length of strophes and reduce gaps between strophes (in type-B songs) on the arrival of females in the vicinity, most probably to increase the song rate, suggesting it to be an indicator of male quality.