From listening to the calls of orangutans to watching primates' alcohol consumption habits, scientists around the world are constantly studying every aspect of animal behavior, and there's still a huge amount of it we don't understand. Now, a team from the University of Zurich (UZH) has worked to unravel the mystery of how ground squirrels remember where they've stashed their food, using, as it turns out, the position of the sun.
The researchers studied colonies of Cape ground squirrels, or Xerus inauris, in the wild at South Africa's Kalahari Research Center. The little rodents have been observed to store their food reserves in multiple hiding spots, and have an uncanny knack of remembering where they've buried the goods, in spite of the sparse vegetation and general lack of reference points that characterize their natural habitat.
For the experiment, the team gave the squirrels food, and recorded where they went off and hid it using GPS. Immediately, the behavior was striking, with the rodents traveling in almost entirely straight lines towards their chosen hiding places, always moving either towards or away from the sun.
"Based on this movement pattern," said UZH's Jamie Samson, "we presume that Cape ground squirrels use the position of the sun at a particular time of day as a rule of thumb to find their bearings when searching for a place to hide their food."
Of course, once the food was stashed away, the squirrels have to be able to find it again. Working on the assumption that the sun played a role in that second part of the equation, the researchers continued their work. Setting up cameras to watch the squirrels at work, they compared the time that the rodents returned to their hidden food with the time of hiding.
The results revealed a strong pattern with the animals usually returning to locations almost exactly 24 hours after hiding the food. Continuing their observations, the team found that the squirrels did sometimes return before that point, but only when the sun was at a mirrored angle in the sky to the 24 hour position.
News that the squirrels use the sun in such a way isn't entirely groundbreaking, with other animals, such as bees and carrier pigeons having been observed to also use it as a navigational aid. The rodents' ability to make use of our home star is, nevertheless, still fascinating and rather impressive.