Food Availability and Animal Space Use Both Determine Cache Density of Eurasian Red Squirrels

Scatter hoarders are not able to defend their caches. A longer hoarding distance combined with lower cache density can reduce cache losses but increase the costs of hoarding and retrieving. Scatter hoarders arrange their cache density to achieve an optimal balance between hoarding costs and main cac...

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Main Authors:	Rong, Ke, Yang, Hui, Ma, Jianzhang, Zong, Cheng, Cai, Tijiu
Format:	Online
Language:	English
Published:	Public Library of Science 2013
Online Access:	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3827212/

id	pubmed-3827212
recordtype	oai_dc
spelling	pubmed-38272122013-11-21 Food Availability and Animal Space Use Both Determine Cache Density of Eurasian Red Squirrels Rong, Ke Yang, Hui Ma, Jianzhang Zong, Cheng Cai, Tijiu Research Article Scatter hoarders are not able to defend their caches. A longer hoarding distance combined with lower cache density can reduce cache losses but increase the costs of hoarding and retrieving. Scatter hoarders arrange their cache density to achieve an optimal balance between hoarding costs and main cache losses. We conducted systematic cache sampling investigations to estimate the effects of food availability on cache patterns of Eurasian red squirrels (Sciurus vulgaris). This study was conducted over a five-year period at two sample plots in a Korean pine (Pinus koraiensis)-dominated forest with contrasting seed production patterns. During these investigations, the locations of nest trees were treated as indicators of squirrel space use to explore how space use affected cache pattern. The squirrels selectively hoarded heavier pine seeds farther away from seed-bearing trees. The heaviest seeds were placed in caches around nest trees regardless of the nest tree location, and this placement was not in response to decreased food availability. The cache density declined with the hoarding distance. Cache density was lower at sites with lower seed production and during poor seed years. During seed mast years, the cache density around nest trees was higher and invariant. The pine seeds were dispersed over a larger distance when seed availability was lower. Our results suggest that 1) animal space use is an important factor that affects food hoarding distance and associated cache densities, 2) animals employ different hoarding strategies based on food availability, and 3) seed dispersal outside the original stand is stimulated in poor seed years. Public Library of Science 2013-11-12 /pmc/articles/PMC3827212/ /pubmed/24265833 http://dx.doi.org/10.1371/journal.pone.0080632 Text en © 2013 Rong et al http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.
repository_type	Open Access Journal
institution_category	Foreign Institution
institution	US National Center for Biotechnology Information
building	NCBI PubMed
collection	Online Access
language	English
format	Online
author	Rong, Ke Yang, Hui Ma, Jianzhang Zong, Cheng Cai, Tijiu
spellingShingle	Rong, Ke Yang, Hui Ma, Jianzhang Zong, Cheng Cai, Tijiu Food Availability and Animal Space Use Both Determine Cache Density of Eurasian Red Squirrels
author_facet	Rong, Ke Yang, Hui Ma, Jianzhang Zong, Cheng Cai, Tijiu
author_sort	Rong, Ke
title	Food Availability and Animal Space Use Both Determine Cache Density of Eurasian Red Squirrels
title_short	Food Availability and Animal Space Use Both Determine Cache Density of Eurasian Red Squirrels
title_full	Food Availability and Animal Space Use Both Determine Cache Density of Eurasian Red Squirrels
title_fullStr	Food Availability and Animal Space Use Both Determine Cache Density of Eurasian Red Squirrels
title_full_unstemmed	Food Availability and Animal Space Use Both Determine Cache Density of Eurasian Red Squirrels
title_sort	food availability and animal space use both determine cache density of eurasian red squirrels
description	Scatter hoarders are not able to defend their caches. A longer hoarding distance combined with lower cache density can reduce cache losses but increase the costs of hoarding and retrieving. Scatter hoarders arrange their cache density to achieve an optimal balance between hoarding costs and main cache losses. We conducted systematic cache sampling investigations to estimate the effects of food availability on cache patterns of Eurasian red squirrels (Sciurus vulgaris). This study was conducted over a five-year period at two sample plots in a Korean pine (Pinus koraiensis)-dominated forest with contrasting seed production patterns. During these investigations, the locations of nest trees were treated as indicators of squirrel space use to explore how space use affected cache pattern. The squirrels selectively hoarded heavier pine seeds farther away from seed-bearing trees. The heaviest seeds were placed in caches around nest trees regardless of the nest tree location, and this placement was not in response to decreased food availability. The cache density declined with the hoarding distance. Cache density was lower at sites with lower seed production and during poor seed years. During seed mast years, the cache density around nest trees was higher and invariant. The pine seeds were dispersed over a larger distance when seed availability was lower. Our results suggest that 1) animal space use is an important factor that affects food hoarding distance and associated cache densities, 2) animals employ different hoarding strategies based on food availability, and 3) seed dispersal outside the original stand is stimulated in poor seed years.
publisher	Public Library of Science
publishDate	2013
url	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3827212/
_version_	1612026505927327744

Food Availability and Animal Space Use Both Determine Cache Density of Eurasian Red Squirrels

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