Vol 14 No 1 (2019)
Articles

Mirrored images but not silicone models trigger aggressive responses in male Common wall lizards

Stefano Scali
Museo di Storia Naturale, Corso Venezia 55, 20121 Milano, Italy
Roberto Sacchi
Dipartimento di Scienze della Terra e dell’Ambiente, Università degli Studi di Pavia, Via Taramelli 24, 27100 Pavia, Italy
Mattia Falaschi
Museo di Storia Naturale, Corso Venezia 55, 20121 Milano, Italy Dipartimento di Scienze e Politiche Ambientali, Università degli Studi di Milano, Via Celoria 26, 20133 Milano, Italy
Alan Coladonato
Dipartimento di Scienze della Terra e dell’Ambiente, Università degli Studi di Pavia, Via Taramelli 24, 27100 Pavia, Italy
Sara Pozzi
Dipartimento di Scienze della Terra e dell’Ambiente, Università degli Studi di Pavia, Via Taramelli 24, 27100 Pavia, Italy
Marco Zuffi
Museo di Storia Naturale, Università degli Studi di Pisa, Via Roma 79, 56011 Calci, Italy
Marco Mangiacotti
Museo di Storia Naturale, Corso Venezia 55, 20121 Milano, Italy Dipartimento di Scienze della Terra e dell’Ambiente, Università degli Studi di Pavia, Via Taramelli 24, 27100 Pavia, Italy
Published June 30, 2019

Abstract

Disentangling the effects of single releasers in animal communication is a demanding task because a releaser often consists of a combination of different key stimuli. Territorial communication in reptiles usually depends on visual, chemical, and acoustic stimuli, but the role of each of them depends on phylogeny. Lacertids are modern lizards that rely mainly on chemical cues for their communication, but they also use aggressive displays based on visual recognition. We experimentally tested the visual stimuli that release an aggressive response in the males of a typical lacertid, the common wall lizard (Podarcis muralis), testing the effects of silicone models and mirrored images in captivity. The response to models and control (a blank sheet) was not significantly different and these stimuli did not release any aggressive behaviour. On the contrary, the reflected image in a mirror caused overt aggression (i.e., bites against it) in 63% of tested individuals. The results clearly demonstrate the role of visual stimuli in territorial communication, but only as a combined effect of shape and motion, differently from other lizard families for which shape is enough to stimulate aggressive responses. Mirrors can be useful tools to investigate aggression related to physiological and morphological aspects in lacertid lizards.