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Open-sea migration of magnetically disturbed sea turtles

  • F Papi
  • P Luschi
  • Susanne Åkesson
  • S Capogrossi
  • G C Hays
Publishing year: 2000
Language: English
Pages: 3435-3443
Publication/Series: Journal of Experimental Biology
Volume: 203
Issue: 22
Document type: Journal article
Publisher: The Company of Biologists Ltd

Abstract english

Green turtles (Chelonia mydas) that shuttle between their Brazilian feeding grounds and nesting beaches at Ascension Island in the middle of the Atlantic Ocean are a paradigmatic case of long-distance oceanic migrants. It has been suggested that they calculate their position and the direction of their target areas by using the inclination and intensity of the earths magnetic field. To test this hypothesis, we tracked, by satellite, green turtles during their postnesting migration from Ascension Island to the Brazilian coast more than 2000 km away. Seven turtles were each fitted with six powerful static magnets attached in such a way as to produce variable artificial fields around the turtle that made reliance on a geomagnetic map impossible. The reconstructed courses were very similar to those of eight turtles without magnets that were tracked over the same period and in the previous year, and no differences between magnetically disrupted and untreated turtles were found as regards navigational performance and course straightness. These findings show that magnetic cues are not essential to turtles making the return trip to the Brazilian coast. The navigational mechanisms used by these turtles remain enigmatic.


  • Biological Sciences


  • ISSN: 1477-9145
Susanne Åkesson
E-mail: susanne [dot] akesson [at] biol [dot] lu [dot] se


Evolutionary ecology

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