Institute of Livestock and Grassland Science, NARO

Wild sika deer that consumes crop matures quickly

-Foraging crops causes further agricultural damage-

Researchers from National Agriculture and Food Research Organization(NARO) have revealed that the maturation of wild sika deer is accelerated by consumption of agricultural crops from the analysis of the nitrogen stable isotope ratios (δ15N value) of deer bone collagen. This result indicates that preventive measures for invasion of deer into farmland and culling of individuals causing feeding damage of agricultural crops are effective in controlling agricultural damage not only now but also in the future. Moreover, since the δ15N value was effective as an index of agricultural crop consumption of deer, it can be expected to be used for elucidating the characteristics of individuals causing feeding damage of agricultural crops using the δ15N value and for developing deer damage management strategies.


Damage to agricultural crops by deer has been confirmed in various parts of the world including Japan, and crop damage is becoming more serious issue with the increasing number of deer. Crops are nutritious and suitable food for deer, but the influence of crop foraging in the growth and reproduction of deer was not yet clarified. It is important to clarify this in order to accurately predict the fluctuations in the number of deer inhabiting the region and for developing effective countermeasures against crop damage.

Therefore, Research group including NARO have shown that δ15N value of bone collagen contained in the bones of wild deer is useful as an index of agricultural crop consumption of deer and also revealed that foraging crops promotes the body size growth of young deer under the age of 4, which results in an increase in pregnancy rate. It was suggested that such "precocious maturity" of deer by crop consumption may promote the population increase of deer. The results of this research were published on April 23 in the scientific journal Ecosphere published by the Ecological Society of America.

Reference Information

Hata A, Nakashita R, Anezaki T, Minami M, Fukue Y, Higuchi N, Uno H, Nakajima Y, Saeki M, Kozakai C, Takada MB (2021) Agricultural crop consumption induces precocious maturity in deer by improving physical and reproductive performance. Ecosphere

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