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Vol. 61, 2022
(update: 2022.5.26)
Bark-stripping Behavior of
Formosan Sambar (Rusa unicolor
swinhoii) at Tataka, Yushan National Park in Taiwan
Guo-Jing Weng1,* , Shu-Mei Chen2,
Li-Min Yin2, I-Chen Wu2, and Ting-An Chou1
doi:10.6620/ZS.2022.61-19
11,
Shuefu Road, Neipu, Pingtung 91201, Taiwan. Institute of Wildlife
Conservation, College of Veterinary Medicine, National Pingtung
University of Science and Technology, Taiwan. *Correspondence: E-mail:
gjw@mail.npust.edu.tw (Weng).
E-mail: m10817012@g4e.npust.edu.tw (Chou)
2515, Sec. 1, Jhongshan Rd., Shueili, Nantou 553203,
Taiwan. Yushan National Park Headquarters, Taiwan. E-mail:
shumeic@ysnp.gov.tw (Chen); limi@ysnp.gov.tw (Yin);
windwardkw@ysnp.gov.tw (Wu)
Received 31 October 2021 / Accepted 2
March 2022
Communicated by Teng-Chiu Lin
The bark-stripping behavior of
Formosan sambar, Rusa unicolor
swinhoii, has become conspicuous in recent years in the Tataka
area, Yushan National Park in Taiwan and caused concerns of visitors
and ecologists. We conducted a monthly survey on 537 tagged trees of 21
species and monitored abundance of sambar using camera traps from
October 2018 to January 2021, aiming to interpret possible causes of
the bark-stripping behavior at Tataka. We also used a generalized
linear model to evaluate potential factors that may affect the
probability of a tree being bark stripped. Both our observations and
the model predictions showed that sambar had a strong preference for
bark of Pinus armandii, Photinia niitakayamensis, and Salix fulvopubeseens and for trees
with diameter at breast height around 14 cm. Bark stripping mainly
occurred between July and October when major forage was most abundant.
However, sambar’s need for bark surged in May when sambar abundance was
moderate and decreased in October when sambar abundance was high. The
seasonality of bark stripping was synchronized with peak period of
antler development, fawn nursing, and spread of gastrointestinal
parasites, suggesting that sambar likely strip bark to ingest minerals
for their physiological needs and/or to acquire plant secondary
metabolites to repel gastrointestinal parasites. Sambar abundance alone
was not sufficient to predict the overall intensity of bark stripping.
Rather, the product of sambar abundance and the necessity index
(average wound size) strongly correlated with the overall
bark-stripping intensity. Therefore, controlling sambar abundance is
essential but it alone may not be the optimal strategy for the control
of bark stripping. A combination of population control and relaxing of
sambar’s parasite loading and/or physiological needs for minerals is an
important strategy to control the overall bark stripping. Future
research could use the necessity index to investigate the synchronicity
of the bark-stripping behavior, deer’s physiological state,
environmental factors and phenology to better understand the cause of
this behavior.
Key words: Deer, Plant
secondary metabolites, Gastrointestinal parasites, Forest, Necessity
index.
Citation: Weng GJ, Chen SM, Yin LM, Wu IC,
and Chou TA. 2022. Bark-stripping behavior of Formosan sambar (Rusa unicolor swinhoii) at Tataka,
Yushan National Park in Taiwan. Zool Stud 61:19. doi:10.6620/ZS.2022.61-19
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