Open AccessAnatomical bases of sex‐ and size‐related acoustic variation in herring gull alarm calls
Author(s) -
Hardouin Loïc A.,
Thompson Richard,
Stenning Martyn,
Reby David
Publication year - 2014
Publication title -
journal of avian biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.022
H-Index - 76
eISSN - 1600-048X
pISSN - 0908-8857
DOI - 10.1111/j.1600-048x.2013.00144.x
Subject(s) - biology , variation (astronomy) , sexual dimorphism , alarm , trait , sexual selection , zoology , bioacoustics , herring gull , alarm signal , evolutionary biology , ecology , herring , larus , acoustics , fishery , fish <actinopterygii> , physics , materials science , astrophysics , computer science , composite material , programming language
The hypothesis that anatomical or physiological factors can constrain the production of vocalizations is supported by an increasing number of examples from a range of taxa, where acoustic variation is related to sex, body‐size or condition. In this study, we combine anatomical and acoustic investigations in herring gulls Larus argentatus to 1) identify co‐variation between sex, body size and the dimensions of the vocal apparatus and 2) test the possible effect of this co‐variation on interindividual variation in the acoustics of alarm calls. We found that the vocal apparatus was sexually dimorphic, with males having longer trachea and bigger vibratile membranes than females. We also identified a relationship between the head–bill length – a secondary sexual trait – and the length of the trachea in males only. However, we failed to identify corresponding sex‐ and body‐size related variation in the acoustic components of alarm calls. We suggest that this absence of a relationship between anatomical and acoustic dimensions may reflect the lack of biomechanical constraints exerted during the production of alarm calls, and that such relationships are more likely to be expressed in this species’ sexual calls, whose production is characterised by more pronounced, ritualised postures that are more likely to highlight inter‐individual size variation.