title: Withered on the stem: is bamboo a seasonally limiting resource for giant pandas?
abstract: In response to seasonal variation in quality and quantity of available plant biomass, herbivorous foragers may alternate among different plant resources to meet nutritional requirements. Giant pandas (Ailuropoda melanoleuca) are reliant almost exclusively on bamboo which appears omnipresent in most occupied habitat, but subtle temporal variation in bamboo quality may still govern foraging strategies, with population-level effects. In this paper, we investigated the possibility that temporal variation in the quality of this resource is involved in population regulation and examined pandas' adaptive foraging strategies in response to temporal variation in bamboo quality. Giant pandas in late winter and early spring consumed a less optimal diet in Foping Nature Reserve, as the availability of the most nutritious and preferred components and age classes of Bashania fargesii declined, suggesting that bamboo may be a seasonally limiting resource. Most panda mortalities and rescues occurred during the same period of seasonal food limitation. Our findings raised the possibility that while total bamboo biomass may not be a limiting factor, carrying capacity may be influenced by subtle seasonal variation in bamboo quality. We recommend that managers and policy-makers should consider more than just the quantity of bamboo in the understory and that carrying capacity estimates should be revised downward to reflect the fact that all bamboos are not equal.
authors.affiliation: Key Laboratory of Southwest China Wildlife Resources Conservation, Ministry of Education, Nanchong, China.
authors.forename: Youxu
authors.initials: Y
authors.lastname: Li
authors.affiliation: Applied Animal Ecology, San Diego Zoo Institute for Conservation Research, San Diego, CA, USA.
authors.forename: Ronald R
authors.initials: RR
authors.lastname: Swaisgood
authors.affiliation: Key Laboratory of Southwest China Wildlife Resources Conservation, Ministry of Education, Nanchong, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Wei
authors.affiliation: Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Yonggang
authors.initials: Y
authors.lastname: Nie
authors.affiliation: Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Yibo
authors.initials: Y
authors.lastname: Hu
authors.affiliation: Wildlife Conservation Division, Sichuan Forestry Bureau, Chengdu, China.
authors.forename: Xuyu
authors.initials: X
authors.lastname: Yang
authors.affiliation: Wildlife Conservation Division, Sichuan Forestry Bureau, Chengdu, China.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Gu
authors.affiliation: Key Laboratory of Southwest China Wildlife Resources Conservation, Ministry of Education, Nanchong, China. zhangzj@ioz.ac.cn.
authors.forename: Zejun
authors.initials: Z
authors.lastname: Zhang
mesh_terms: D000818:Animals; D003247:Conservation of Natural Resources; D017753:Ecosystem; D005247:Feeding Behavior; D031787:Sasa; D012621:Seasons; D001503:Ursidae
keywords: Bamboo biomass; Diet; Energetic constraints; Foraging strategy; Population regulation