Initial orientation and homing performances in the lacertid lizard Podarcis siculus

Abstract

Homing abilities of lizards after experimental dislocations have been found to be well developed in several species. Following our preliminary findings in Podarcis siculus, the present paper reports a new series of experiments on homing performances and initial orientation behaviour upon release. For this purpose, three series of releases were performed at increasing distances from the home areas in which the lizards were captured (range 85–245 m). In each series, two groups of lizards were released: the route-based visual cues during displacement were denied to one of them (NVIS), but allowed for the other (YVIS). The results of initial orientation showed that both are significantly homeward oriented at all three distances tested. Male and female YVIS and female NVIS are similarly homeward oriented, while the male NVIS are not. All 74 lizards successfully returned to their respective home areas. Eleven lizards homed on the same day they were released, while most of them homed during the 1st day after release (n = 51) and the rest on the 2nd day (n = 12). The different transport treatments did not influence homing success at the different distances tested. These results seem to support the use of a geocentric pilotage strategy to re-enter home from the release spot. Alternatively, the possibility that P. siculus use a sun compass and a mosaic map to find their way home is also discussed.

Key Words:

• homeward heading
• geocentric strategy
• displacement experiment
• visual cue

Acknowledgements

We would like to thank: Dimitri Giunchi for his helpful feedback on an earlier version of the manuscript; Paolo Emilio Tomei for botanical information; Daniele Santerini for preparing the figures; Giulia Cerritelli for helping us in the data analyses; Wendy Doherty for the English language editing; Ulrich Sinsch and two other anonymous referees who greatly improved the final version with their criticisms and suggestions, as well as the management of the “Tenuta di San Rossore” (Pisa).

DISCLOSURE STATEMENT

No potential conflict of interest was reported by the authors.

ETHICAL STANDARD

All protocols performed in the study involving animals comply with the ethical standards and Italian laws on animal welfare.