A camera trap recording a Eurasian red squirrel hoarding the walnut and retrieving it in Hokkaido, Japan

Abstract

We recorded a Eurasian red squirrel Sciurus vulgaris hoarding a Japanese walnut Juglans mandshurica on the ground and retrieving it, using an infrared-triggered camera installed in Hokkaido University, Japan. The Eurasian red squirrel hoarded a walnut on December 16th, 2021, in non-snowy conditions, and that retrieved it from 21 cm under snow on January 8th, 2022 (23 days after hoarding). In this case study, the squirrel did not use olfactory or visual memory, suggesting that the Eurasian red squirrels emphasize spatial memory to find stored food. The fact that the squirrel reached the walnut hoarding site without confusion, even though it did not reconfirm the site during the 23 days, suggests that a Eurasian red squirrels have a very accurate memory.