Adaptive management of sika deer populations in Hokkaido, Japan: theory and practice |
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Authors: | Koichi Kaji Takashi Saitoh Hiroyuki Uno Hiroyuki Matsuda Kohji Yamamura |
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Institution: | (1) Faculty of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwaicho, Fuchu 183-8509, Japan;(2) Field Science Center, Hokkaido University, Sapporo 060-0811, Japan;(3) Institute of Environmental Sciences, Hokkaido Research Organization, Sapporo 060-0819, Japan;(4) Department of Environmental Management, Yokohama National University, Yokohama 239-8501, Japan;(5) Laboratory of Population Ecology, National Institute for Agro-Environmental Sciences, Tsukuba 305-8604, Japan |
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Abstract: | We investigated the utility of adaptive management (AM) in wildlife management, reviewing our experiences in applying AM to
overabundant sika deer (Cervus nippon) populations in Hokkaido, Japan. The management goals of our program were: (1) to maintain the population at moderate density
levels preventing population irruption, (2) to reduce damage to crops and forests, and (3) to sustain a moderate yield of
hunting without endangering the population. Because of significant uncertainty in biological and environmental parameters,
we designed a “feedback” management program based on controlling hunting pressure. Three threshold levels of relative population
size and four levels of hunting pressure were configured, with a choice of four corresponding management actions. Under this
program, the Hokkaido Government has been promoting aggressive female culling to reduce the sika deer population since 1998.
We devised a harvest-based estimation for population size using relative population size and the number of deer harvested,
and found that the 1993 population size (originally estimated by extrapolation of aerial surveys) had been underestimated.
To reduce observation errors, a harvest-based Bayesian estimation was developed and the 1993 population estimate was again
revised. Analyses of population trends and harvest data demonstrate that hunting is an important large-scale experiment to
obtain reliable estimation of population size. A serious side effect of hunting on sika deer was inadvertent lead poisoning
of large birds of prey. The prohibition of the use of lead bullets by the Hokkaido Government was successful in reducing the
lead poisoning, but the problem still remains. Two case studies on sika population irruption show that the densities set by
maximum sustainable yield may be too high to prevent damage to agriculture, forestry, and/or ecosystems. Threshold management
based on feedback control is better for ecosystem management. Since volunteer hunters favor higher hunting efficiency in resource
management (e.g., venison), it is necessary to support the development of professional hunters for culling operations for
ecosystem management, where lower densities of deer should be set for target areas. Hunting as resource management and culling
for ecosystem management should be synergistically combined under AM. |
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Keywords: | Cervus nippon Density dependence Feedback management Maximum sustainable yield Population dynamics |
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