Flying squirrels use a mortise-tenon structure to fix nuts on understory twigs
- Chinese Academy of Forestry, China
- Hainan University, China
- University of Alberta, Canada
- Sun Yat-sen University, China
Abstract
Squirrels of temperate zones commonly store nuts or seeds under leaf litter, in hollow logs or even in holes in the ground; however, in the humid rainforests of Jianfengling in Hainan, South China, we show that some flying squirrels cache elliptical or oblate nuts by hanging them securely in vegetation. These small flying squirrels were identified as Hylopetes phayrei electilis (G. M. Allen, 1925) and Hylopetes alboniger (Hodgson, 1870), in video clips captured of their behavior around focal nuts. Squirrels chewed grooves encircling ellipsoid nuts or distributed on the bottoms of oblate nuts, and then used these grooves to fix nuts tightly between small twigs 0.1-0.6 cm in diameter that were connected at angles of 25-40°. The grooves carved on the nuts (concave structure) connected with Y-shaped twigs (convex structure) and thus firmly affixed the nuts to the plant in a way similar to a mortise-tenon joint used in architecture and carpentry. Cache sites were on small plants located 10-25 m away from the closest potentially nut-producing tree, a behavior that likely reduces discovery and consumption of the nuts by other animals. The adaptive squirrel behavior that shapes and fits nuts between twigs seems to be directed at providing more secure storage that increases food supply during dry periods in a humid tropical rainforest. In addition to providing such benefits for the squirrels, we suggest that this behavior also impacts the distribution of tree species in the forest.
Data availability
All data are available in the main text or the supplementary files.
Article and author information
Author details
Funding
Science and Technology Basic Work Project from Ministry of Science and Technology of the People's Republic of China (2019FY101607)
- Han Xu
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Reviewing Editor
- Ammie K Kalan, University of Victoria, Canada
Version history
- Received: November 16, 2022
- Preprint posted: November 21, 2022 (view preprint)
- Accepted: May 26, 2023
- Accepted Manuscript published: June 13, 2023 (version 1)
- Version of Record published: July 7, 2023 (version 2)
Copyright
© 2023, Xu et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Flying squirrels use a mortise-tenon structure to fix nuts on understory twigs
eLife 12:e84967.
https://doi.org/10.7554/eLife.84967
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