Elephant seal's map sense tells them when to head `home'

Date:
February 28, 2022
Source:
Cell Press
Summary:
Each year, pregnant female elephant seals take an approximately
240-day trek over 10,000 kilometers across the Eastern North Pacific
Ocean before returning to their breeding beaches to give birth
within five days of their arrival. Now, a study finds that this
impressive navigation ability depends on an internal map sense,
which functions much like a built-in GPS.



FULL STORY ==========================================================================
Each year, pregnant female elephant seals take an approximately 240-day
trek over 10,000 kilometers across the Eastern North Pacific Ocean before returning to their breeding beaches to give birth within five days of
their arrival. Now, a study appearing February 28 in the journal biology Current Biology finds that this impressive navigation ability depends
on an internal map sense, which functions much like a built-in GPS.


==========================================================================
"We found that migrating elephant seals know how far they are from their breeding beach thousands of kilometers away," said Roxanne Beltran of
the University of California Santa Cruz. "They also know approximately
how long it will take them to get back." Beltran and her colleagues,
including Dan Costa, knew that elephant seals are expert navigators. What
they didn't know was how the seals manage to make it back to the beach
just in time for the breeding season.

In the new study, the researchers used satellite tracking data collected
from more than 100 adult female seals. They figured out when each of
them turned around to head back to the beach where they started from.

The data revealed that seals decided to turn around based strongly on
how far away they were from where they needed to go. Their decisions to
turn around weren't related to their body condition, measured as amount
of body fat.

"We were surprised that foraging success or percent body fat was
not more strongly related to when seals begin the return portion of
the migration," Beltran said. "We expected that highly successful
(i.e. fatter) seals might end their foraging trips earlier, but that
was not the case; instead, it seems like they are well programmed to
turn around strategically based on where they are and in turn how long
it will take them to get back." The researchers don't yet know what
sensory cues the elephant seals depend on to keep track of where they
are and head in the right direction at the right time, but it's clear
that they can adjust the timing of their travels based on an internal perception of time and space.

The results help to better understand elephant seals, with important implications for their conservation, the researchers say. In future
studies, they hope to quantify exactly how precise the seals' navigation ability is and determine which cues are most important.

The work was funded by the Office of Naval Research, the E&P Sound and
Marine Life Joint Industry Project of the International Association of
Oil and Gas Producers, and the National Science Foundation.

========================================================================== Story Source: Materials provided by Cell_Press. Note: Content may be
edited for style and length.


========================================================================== Journal Reference:
1. Roxanne S. Beltran, Alexander L. Yuen, Richard Condit, Patrick W.

Robinson, Max F. Czapanskiy, Daniel E. Crocker, Daniel
P. Costa. Elephant seals time their long-distance migrations
using a map sense. Current Biology, 2022; 32 (4): R156 DOI:
10.1016/j.cub.2022.01.031 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/02/220228114341.htm

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