Newts can use spatial variation in the magnetic field (MF) to derive geographic position, but it is unclear how they detect the ‘spatial signal’ which, over the distances that newts move in a day, is an order of magnitude lower than temporal variation in the MF. Newts take map readings using their light-dependent magnetic compass to align a magnetite-based ‘map detector’ relative to the MF. Time-of-day, location, and light exposure (required by the magnetic compass) were varied to determine when newts obtain map information. Newts were displaced from breeding ponds without access to route-based cues to sites where they were held and/or tested under diffuse natural illumination. We found that: (1) newts held overnight at the testing site under diffuse illumination exhibited accurate homing orientation, but not if transported to the testing site on the day of testing, (2) newts held overnight under diffuse lighting at a ‘false testing site’ and then tested at a site located in a different direction from their home pond, oriented in the home direction from the holding site, not from the site where they were tested, (3) newts held overnight in total darkness (except for light exposure for specific periods) only exhibited homing orientation the following day if exposed to diffuse illumination during the preceding evening twilight in the ambient MF. These findings demonstrate that, to determine the home direction, newts require access to light and the ambient MF during evening twilight when temporal variation in the MF is minimal.
Use of a high resolution magnetic map by a short distance migrant, the alpine newt (Ichthyosaura alpestris)?
- Views Icon Views
Article Versions Icon
- Accepted Manuscript 11 June 2021
- Share Icon Share
- Search Site
Francisco J. Diego-Rasilla, John B. Phillips; Use of a high resolution magnetic map by a short distance migrant, the alpine newt (Ichthyosaura alpestris)?. J Exp Biol 2021; jeb.238345. doi: https://doi.org/10.1242/jeb.238345
Download citation file: