{"id":9686,"date":"2015-01-15T12:26:05","date_gmt":"2015-01-15T17:26:05","guid":{"rendered":"https:\/\/college.unc.edu\/?p=9686"},"modified":"2024-07-02T16:07:04","modified_gmt":"2024-07-02T16:07:04","slug":"turtleshome","status":"publish","type":"post","link":"https:\/\/collegearchive.unc.edu\/?p=9686","title":{"rendered":"For sea turtles, there\u2019s no place like magnetic home"},"content":{"rendered":"
\"Ken<\/a>
UNC biologist Ken Lohmann studies migration patterns of sea turtles. (photo by Dan Sears)<\/figcaption><\/figure>\n

Adult sea turtles find their way back to the beaches where they hatched by seeking out unique magnetic signatures along the coast, according to new evidence from the University of North Carolina at Chapel Hill.<\/p>\n

The findings will be reported in the Cell Press journal Current Biology <\/em>on Jan. 15.<\/p>\n

\u201cSea turtles migrate across thousands of miles of ocean before returning to nest on the same stretch of coastline where they hatched, but how they do this has mystified scientists for more than fifty years,\u201d said J. Roger Brothers of the College of Arts and Sciences at the University of North Carolina at Chapel Hill. \u201cOur results provide evidence that turtles imprint on the unique magnetic field of their natal beach as hatchlings and then use this information to return as adults.\u201d<\/p>\n

While earlier studies have shown that sea turtles use the Earth\u2019s magnetic field as a guide while out at sea, it has remained unclear whether adult turtles also depend on magnetic features to recognize and return to the nesting sites chosen by their mothers before them, the researchers explain.<\/p>\n

Several years ago, biologist Kenneth Lohmann, who is also in the College and is the co-author of the new study, proposed that animals including sea turtles and salmon might imprint on magnetic fields early in life, but that idea has proven difficult to test in the open ocean. In the new study, Brothers and Lohmann took a different approach by studying changes in the behavior of nesting turtles over time.<\/p>\n

\u201cWe reasoned that if turtles use the magnetic field to find their natal beaches, then naturally occurring changes in the Earth\u2019s field might influence where turtles nest,\u201d Brothers said.<\/p>\n

To investigate, the researchers analyzed a 19-year database of loggerhead nesting along the eastern coast of Florida, the largest sea turtle rookery in North America. They found a strong association between the spatial distribution of turtle nests and subtle shifts in the Earth\u2019s magnetic field.<\/p>\n

In some times and places, the Earth\u2019s field shifted so that the magnetic signatures of adjacent locations along the beach moved closer together. When that happened, nesting turtles packed themselves in along a shorter stretch of coastline, just as the researchers had predicted. In places where magnetic signatures diverged, sea turtles spread out and laid their eggs in nests that were fewer and farther between.<\/p>\n

Brothers said that little is known about how turtles detect the geomagnetic field. Most likely, tiny magnetic particles in the turtles\u2019 brains respond to the Earth\u2019s field and provide the basis for the magnetic sense, but no one knows for sure.<\/p>\n

Sea turtles likely go to great lengths to find the places where they began life because successful nesting requires a combination of environmental features that are rare: soft sand, the right temperature, few predators and an easily accessible beach.<\/p>\n

\u201cThe only way a female turtle can be sure that she is nesting in a place favorable for egg development is to nest on the same beach where she hatched,\u201d Brothers said. \u201cThe logic of sea turtles seems to be that \u2018if it worked for me, it should work for my offspring.\u2019<\/p>\n","protected":false},"excerpt":{"rendered":"

Adult sea turtles find their way back to the beaches where they hatched by seeking out unique magnetic signatures along the coast, according to new evidence from the University of North Carolina at Chapel Hill. (green sea turtle image courtesy of Andresvilla92, Wikimedia Commons)<\/p>\n","protected":false},"author":4,"featured_media":9689,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center 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