Behavioral Ecology Advance Access originally published online on July 13, 2009
Behavioral Ecology 2009 20(5):1050-1055; doi:10.1093/beheco/arp096
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Behavioral adaptation of Pallas's squirrels to germination schedule and tannins in acorns
a State Key Laboratory of Integrated Management of Pest Insects and Rodents in Agriculture, Institute of Zoology, Chinese Academy of Sciences, Datun Lu, Chaoyang District, Beijing 100101, China b Anhui Provincial Key Laboratory of the Conservation and Exploitation of Biological Resources, College of Life Sciences, Anhui Normal University, Wuhu 241000, China c Key Laboratory of Bio-resources and Eco-environment, Ministry of Education, College of Life Science, Sichuan University, Chengdu 610064, China
Address correspondence to Z. Zhang. E-mail: zhangzb{at}ioz.ac.cn.
 |
Abstract |
|---|
Using acorns from Castanea henryi (CH) and Quercus variabilis (QV) with contrasting germination schedule (related to food perishability) and tannin levels, we conducted field experiments in a subtropical forest in Southwest China to investigate how free-ranging Pallas's squirrels (Callosciurus erythraeus) utilize acorns as long-term storage based on the food perishability and high-tannin hypotheses. Though QV acorns germinated much earlier than CH ones, we found that Pallas's squirrels hoarded more high-tannin QV acorns over low-tannin CH ones, supporting the high-tannin hypothesis (but not the food perishability hypothesis). However, several other predictions derived from the food perishability hypothesis received sound support: nondormant QV acorns had their embryos removed with a higher probability (68.5%) than dormant CH ones (8.8%) and embryo-removed acorns had a much lower germination success but had a higher probability surviving as long-term storage. During the caching-recovery process, hoarding animals actively detected acorn state (dormant or not) and removed acorn embryos with an increasing probability in subsequent hoarding events. In addition, embryo-removed acorns could serve as long-term storage because they had a very low probability being infested by fungi as intact acorns did during the time of storage. We conclude that tree squirrels can differentially respond to acorn germination and remove the embryos of nondormant acorns more frequently as long-term storage, but tannin level is more important in determining whether a given acorn is hoarded or not. Combined with the studies from North America, our results suggest convergent evolution of acorn hoarding behavior in tree squirrels across different continents.
Key words: behavioral decisions, germination schedule, long-term food supply, scatter hoarding, tannins, tree squirrels.
Received 3 March 2009; revised 19 May 2009; accepted 9 June 2009.
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  Z. Xiao, X. Gao, M. A. Steele, and Z. Zhang Frequency-dependent selection by tree squirrels: adaptive escape of nondormant white oaks Behav. Ecol., November 26, 2009; (2009) arp169v1. [Abstract] [Full Text] [PDF]
|
|