Yabe T., Minato Ryu-ichi, Hashimoto T. 2017. Breeding under snow cover in Norway rats (Rattus norvegicus) on uninhabited islands in Hokkaido, Japan // Russian J. Theriol. Vol.16. No.1: 43–46 [in English].

Tatsuo Yabe [rccty@js8.so-net.ne.jp], Tropical Rat Control Committee, OADA, Asia Center, 8-10-32 Akasaka, Minato-Ku, Tokyo 107-0052, Japan; Ryu-ichi Minato[rminato@jwrc.or.jp], Japan Wildlife Research Center, 3-3-7 Kotobashi, Sumida-Ku, Tokyo 130-8606, Japan; Takuma Hashimoto [thashimoto@jwrc.or.jp], Japan Wildlife Research Center, 3-3-7 Kotobashi, Sumida-Ku, Tokyo 130-8606, Japan.

doi: 10.15298/rusjtheriol.16.1.04

ABSTRACT. We analyzed age distribution of Norway rats (Rattus norvegicus) on uninhabited islands, Yururi (168 ha) and Moyururi (31 ha) in the subarctic climate zone in Hokkaido, Japan. Age was estimated from eye lens weight. From the age distribution of 73 rats caught in July–August 2013, we found that 10 rats of them were born under the snow cover from December to March.

KEY WORDS. Age distribution, breeding, Hokkaido, Japan, Rattus norvegicus, snow cover, uninhabited islands.

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