Gulps, wheezes, and sniffs: how measurement of beak movement in sea turtles can elucidate their behaviour and ecology Sandra Hochscheid a,b, * , Fulvio Maffucci a , Flegra Bentivegna a , Rory P. Wilson b a Stazione Zoologica Anton Dohrn, Villa Comunale 1, 80121 Napoli, Italy b School of Biological Sciences, Institute of Environmental Sustainability, University of Wales Swansea, Singleton Park, Swansea, SA2 8PP, UK Received 7 July 2004; received in revised form 23 September 2004; accepted 14 October 2004 Abstract This study was performed to assess the extent to which an intermandibular angle sensor (IMASEN) may be used to elucidate the behaviour of six captive loggerhead turtles. The measuring system was glued to the beak of turtles and set to measure the intermandibular distance at 5 Hz while the turtles fed (on anchovies, squid, and live crabs), swam, rested, and breathed. The behaviour of the equipped turtles was filmed and compared afterwards to the sensor readings. The IMASEN output data allowed quantification of the number of food items ingested as well as the time between food seizure and deglutition and the type of food ingested. However, nonfeeding turtles exhibited regular jaw movements with a reduced amplitude of ca. 2.2 mm, which clearly differed from feeding movements and were caused by buccal oscillations. Such movements of the base of the buccal cavity generate a steady flow of water pass the chemosensory organs and were interrupted only during food ingestion, resting, and breathing. Breathing was clearly distinguishable by the IMASEN. The beak sensor is thus a reliable system to investigate a number of behaviours in sea turtles which encompass foraging, buccal oscillation, and respiratory frequency. It has potential for allocating time to different activities in free-ranging sea turtles and thus allows us to gain insight to their foraging and diving strategies. D 2004 Elsevier B.V. All rights reserved. Keywords: Behaviour; Buccal oscillation; Datalogger; Feeding; Hall sensor; Respiration 1. Introduction Animal-attached technology has become a major tool in the study of the behaviour and physiology of marine vertebrates. A vast range of available telemetry systems now allows the movements and even phys- iological parameters of unrestrained diving animals to be monitored. Sea turtles, in particular, have been equipped with various devices ever since Carr’s pioneering studies in the early 1960s, which revealed the turtles remarkable ability to migrate across the open ocean (Carr, 1963; Luschi et al., 1996; Nichols et al., 2000; Hays et al., 2003). Since then, detailed 0022-0981/$ - see front matter D 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.jembe.2004.10.004 * Corresponding author. Stazione Zoologica Anton Dohrn, Villa Comunale 1, 80121 Napoli, Italy. Tel.: +39 081 5833 400; fax: +39 081 5833 294. E-mail address: hochs@szn.it (S. Hochscheid). Journal of Experimental Marine Biology and Ecology 316 (2005) 45 – 53 www.elsevier.com/locate/jembe