TWO DISTINCT SONG POPULATIONS OF BLUE TIT PARUS CAERULEUS IN THE FRENCH MEDITERRANEAN

Abstract

Blue tits, as many other species, show much geographic variation in their songs. In blue tits, songs that include a trill (series of rapidly repeated notes) are widespread on the European mainland, but have not been reported in North Mrica or the Canary Islands. We studied song structure of two blue tit populations from the French Mediterranean that are exposed to large differences in local selection pressures (food, vegetation, social factors). Songs £rom populations on the European mainland and the island of Corsica differed much in syntax, tempo, frequency, and the incidence of trills. The observed population differences could potentially be caused by a combination of different factors, including biotic and abiotic habitat characteristics, body size, and cultural drift. We suggest that songs without trill are acoustically adapted for transmission in habitats where the local breeding density of great tits is low. In addition, we suggest that songs with trill may reflect a character shift, to minimise territorial interactions with great tits.

Is phenotypic variation of blue tits (Parus caeruleus L.) in Mediterranean mainland and insular landscapes adaptive?

“…A considerable and unexpected variation for all the traits examined, including breeding traits [5,9,40,41]' behaviour (e.g. aggressiveness) [49], song structure [24,25], and morphometry, has been found on the scale of the two regions combined, with a clear distinction between mainland and Corsican populations. Table I gives some examples of this variation.…”

Blue Tit song repertoire size, male quality and interspecific competition

“…Blue Tits emit songs with two principal kinds of syntax ( Fig. 1): songs with trill and songs without trill (a trill is a series of identical notes repeated extremely rapidly; Bijnens and Dhondt 1984, Cramp and Perrins 1993, Schottler 1995, Doutrelant et al 1998. A previous study (C. Doutrelant and M. Lambrechts unpubl.…”

Macrogeographic Variation in Song – a Test of Competition and Habitat Effects in Blue Tits

“…2001). On the European mainland at a continental scale, all recorded blue tits produce songs with a trill, which dominate the song repertoires in these populations (Bijnens & Dhondt 1984; Cramp & Perrins 1993; Doutrelant et al. 1998, 2001).…”

“…In the six blue tit populations we studied, the presence/absence of a trill characterized song variation in frequency, duration and syntax (Doutrelant et al 2001). On the European mainland at a continental scale, all recorded blue tits produce songs with a trill, which dominate the song repertoires in these populations (Bijnens & Dhondt 1984;Cramp & Perrins 1993;Doutrelant et al 1998Doutrelant et al , 2001. In North Africa and the Canary Islands, songs with a trill were never reported in blue tits (Bijnens & Dhondt 1984;SchoÈ ttler 1995;Martens 1996).…”

“…In North Africa and the Canary Islands, songs with a trill were never reported in blue tits (Bijnens & Dhondt 1984;SchoÈ ttler 1995;Martens 1996). On Corsica, in the Mediterranean region, blue tits mainly sing song types without a trill, but local populations dier in the proportion of songs with a trill (Doutrelant et al 1998;Doutrelant et al 2001). To investigate the factors in¯uencing geographic variation in the proportion of blue tit songs with a trill, we conducted a comparative study testing predictions of the following four hypotheses.…”