Small Japanese mole

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Small Japanese mole
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Eulipotyphla
Family: Talpidae
Genus: Mogera
Species:
M. i. . H. 2. (.) K. 1957)[2][3]
Binomial name
Mogera imaizumii Hutterer, 2005[1] (Kuroda 1957)[2][3]
Kuroda, 1936
Small Japanese mole range
Synonyms

Mogera wogura minor Kuroda, 1936;[1] Talpa micrura imaizumii (Kuroda, 1957);[1] Mogera minor Hutterer, 1993[1]

The small Japanese mole,[2] lesser Japanese mole[3][4][1] or Japanese Eastern Mole[1] (Mogera imaizumii) is a species of mammal in the family Talpidae. It is endemic to Japan.

Distribution

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Populations of the species occur mostly in Eastern and Northern Honshū (mainland of Japan).[5] Namely, Shizuoka, Nagano, and Ishikawa Prefectures and further north up to the mountainous edges of the Shimokita Peninsula.[6] except for a portion of the Echigo Plain of Niigata Prefecture. They are also found in sporadic populations in mountainous regions in the West and South,[8] in mountains terrains within Kyoto Prefecture and the city of Shōbara, Hiroshima, in the Suzuka Mountains in Mie, southern Kii Peninsula (Wakayama), Mount Tsurugi, Mount Ishizuchi, etc. in Shikoku, and parts of Shōdo Island. It is endemic to Japan.[3][9]

Although it can still be found within the inner city (23 wards of Tokyo) in places where crop fields remain, but they become scarce when such sites undergo urban development. For example, they are rarely spotted inside the circular track of the Yamanote Line. However, it is found within the grounds of the Imperial Palace. These moles were cut off from the surrounding environment after the completion of the palace moat in the 1630s, and the isolated gene pool is thought to have survived since then within the palace grounds. However, DNA sequence studies have shown the population to have a 98.5% close match to the genetics of moles found in Hino, Tokyo and confirmed to be the same species as the M. imaizumii of the Kantō region.[5][10][a]

Mole war

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Thus eastern Japan is essentially the "territory" of the lesser Japanese mole (azuma mogura, lit. "eastern mole"), and western Japan is the territory of the Japanese mole (M. wogura, referred to as the "Kobe mole" in Japan).[7] This competition over habitat has been dubbed mogura sensō (モグラ戦争; "mole war"), and the boundary ("front") was once west of Mount Fuji (Shizuoka Prefecture)[12] but moved to Mount Hakone (Kanagawa Prefecture),[13] and later to the northern limits of Mt. Hakone, so that that the encroachment of the bigger species into Kantō may be imminent.[14] Mt. Fuji and Mt. Hakone have corridors of hardened lava flow which are thought to have posed barriers preventing the larger species' encroachment.[12]

The isolated population groups are considered to be remnants[9] of a much more widespread population that once existed in the west, in fact all over Japan,[15] but this older type mole has kept losing its habitat to the bigger species.[7]

It is thought that M. imaizuimi in mountain terrains have been protected from incursion by the M. wogura due to shallower soil layers that are not optimal habitat for the larger species. Kii peninsula and Shōdo Island owing to their cliffs have shallow-soil zones that also prevent their incursion.[9]

Morphology

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They measure a full length of 12.1 to 15.9 centimetres (4.8 to 6.3 in), with tail length 1.4 to 2.2 centimetres (0.55 to 0.87 in), weighing 48 to 127 grams (1.7 to 4.5 oz).[3] There is considerable variation in size, and the mountainous populations are smaller while the Pacific coastal plain populations tend to be larger, almost double by weight.[3] They have poor eyesight, and the tails are short.[16][b] Dark-brown furred in mountainous regions, more brownish tinted in floodplain populations.[3]

The naked (hairless) area on its upper snout is rectangular-shaped.[c][3] Palate of normal size and length.[3] Upper incisors aligned in widened V-shape fashion.[3] 3 upper premolars per each (right or left) side, 2 lower premolars per side.[3]

Komogura types

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The appellation komogura (コモグラ; lit. "small mole") had been applied to Japanese mammologists to refer to the dwarf populations dwelling in hilly, mountainous, or plateau habitats, reserving the common name azumamogura (アズマモグラ; lit. "eastern mole") for normal-sized populations in plains, crop fields, etc.[17]

Nagamichi Kuroda had published komogura as subspecies, later renaming it (Mogera wogura minor Kuroda, 1936; Talpa micrura imaizumii (Kuroda, 1957))[18] But the ASM (American Society of Mammalogists) database registers these as synonym for the species.[1]

Sexing

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Female moles close their vaginal openings except during breeding season (though they are not known to close completely in Japanese species), and since males do not have an exterior hanging scrotum either,[20], which makes sexing the males and females difficult or easily mistakable.[21] However, [[anogenital distance] (AGD) measurements can be used to determine the sex.[citation needed]

Behavioral traits

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Their habitat ranges from grassland plains or farmed lands in the lowlands to forested hills and mountainous terrain, but prefer the moist, deep soil in the plains.[3] They burrow tunnels underground in which they live. The removed soil are taken to the surface to form mole mounds. They live on a cycle of shifting from activity to rest 3 times a day.[3]

In February 2025, a Yamagata University team reported on the distribution densities of the species in mountain forests, with quantified population analysis comparing different sites.[22] The study involved thorough investigation of the species' tunnels found while trekking the hiking paths, and found that the population density varied greatly according to the forest type (vegetation) and soil environments, and that abundance of earthworms correlated with the mole's abundance.[23]。

Although they mainly prey on insects and earthworms, they also feed on soil centipedes,leeches, and plant seeds.[3]

They build their nest deep in the forest, about 40 centimetres (16 in) diameter and 36 centimetres (14 in) height, where they gather deciduous leaves for lining, in order to breed. They have their litter in the spring (sometimes fall), with 1 to 6 pups per birth.[3] A study of the microsatellite genetic markers on the mother and 3 offspring revealed a single father for the offspring.[24] and follow-up studies using greater number of samples is anticipated.[25] Their lifespan is approximately 3 years.[3]

Conservation status

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The species as a whole is rated least concern conservation status by the IUCN.[2][1]

The Red Data Book for some of the prefectures across Japan have listed the species' endangered statuses as follows:[26]

Expalantory notes

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  1. ^ There are alsopockets of sites in the Tokyo area where the mole has been extirpated, but some specimens have been preserved which were used in the comparative DNA study.[11]
  2. ^ Which are characteristics common to Moger genus and monotypic Oreoscaptor mizura moles of Japan.
  3. ^ This trait is common to Moger genus overall in Japan.

References

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Notes

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  1. ^ a b c d e f g h "Mogera imaizumii". ASM Mammal Diversity Database. 2.2. American Society of Mammalogists. Retrieved 7 July 2025.
  2. ^ a b c d Cassola, F. (2016). "Mogera imaizumii". IUCN Red List of Threatened Species. 2016: e.T41465A22323581. doi:10.2305/IUCN.UK.2016-2.RLTS.T41465A22323581.en. Retrieved 7 July 2025.
  3. ^ a b c d e f g h i j k l m n o Abe, Hisashi (2008). "Azuma mogura" アズマモグラ. Nihon no honyūrui 日本の哺乳類 (2nd Rev. ed.). Tokai University. p. 23. ISBN 9784096771051.
  4. ^ Endō et al. (2000).
  5. ^ a b Takeda, Masatsune [in Japanese]; Matsuura, Keiichi [in Japanese]; Nomura, Shūhei; Ōwada, Mamoru　; Tomokuni, Masaaki; Shinohara, Akihiko (December 2000a). "Kōkyo no seibutsusō: II. Dōbutsu-sō (konchū wo nozoku)" 皇居の生物相 ： II. 動物相（昆虫を除く） [Flora and Fauna of the Imperial Palace, Tokyo. II. Fauna, Excluding Insects]. Memoirs of the National Museum of Nature and Science 国立科学博物館専報 (35): 2.
  6. ^ "Osorezan sanchi sōgō shinrin chōsa 6. Yasei seibutsu" 恐山山地総合森林調査 報告書 6.野生生物 (PDF). Forestry Agency (Japan). March 1994. pp. 76–77. Retrieved 2025-06-12.
  7. ^ a b c Suzuki, Shigetada; Miyao, Takeo [in Japanese]; Nishizawa, Toshiaki; Takada, Yasushi (1979). "Kiso Komagatake no honyū dōbutsu ni kansuru kenkyū dai-5 hō Kiso Komagatake higashi shamen ni okeru mizura mogura no seisoku kakunin ni tsuite" 木曾駒ケ岳の哺乳動物に関する研究 第Ⅴ報　木曾駒ケ岳東斜面におけるミズラモグラ（Euroscaptor mizur）の生息確認について [Studies on Mammals of the Mt. Kiso-Komagatake, Central Japan Alps V. Description of the japanese Mountain Mole (Euroscaptor mizura) on the Eastern Slope of the Mt. Kiso-Komagatake] (PDF). 信州大学農学部紀要 [Journal of the Faculty of Agriculture, Shinshu University]. 16 (1): 44. snippet@google
  8. ^ "西南本州で確認される本種は、"西南本州では山地に飛石的に分布しているにすぎない"[7]
  9. ^ a b c Abe, Hisashi (2001). "Mogura-rui ni okeru izon kotaigun to sono iji kikō" モグラ類における遺存個体群とその維持機構. Honyūruigaku kagaku 哺乳類科学 [Mammalian Science]. 41 (1): 35–52. doi:10.11238/mammalianscience.41.35.
  10. ^ National Museum of Nature and Science, Imperial Palace Flora and Fauna Study Group (2001). Kōkyo Fukiage Gyoen no ikimono 皇居・吹上御苑の生き物. Seikai Bunkasha. pp. 68–51. ISBN 4418013032.
  11. ^ Endō et al. (2000), p. 49: "Since the present study examined some specimens from sites of the Tokyo Metropolitan Area , in which the population has been already extinct , the present morphological data are noteworthy".
  12. ^ a b Horikoshi, Masuoki; et al. (Ishikawa, Ryōsuke; Ōba, Hideaki; Higuchi, Hiroyoshi) (1985). Horikoshi, Masuok; Aoki, Jun'ichi [in Japanese] (eds.). "Nihon no seibutsu" 日本の生物. Vol. 6. Iwanami Shoten. p. 55.
  13. ^ Data Shizuoka; Shizuoka nenkan データしずおか: 静岡年鑑. Shizuoka Shinbunsha. 2020. p. 297.
  14. ^ Imaizumi, Tadaaki [in Japanese] (12 July 2019). "Mogura sensō" モグラ戦争. Nikkei.
  15. ^ Nakajima, Hiroshi [in Japanese] (1978). Umoreta kodaishi: Nihon shoki hensan no nazo wo saguru 埋もれた古代史: 日本書紀編纂の謎を探る. 圭文社. p. 233.
  16. ^ "Kawasemi tsūshin No. 90" カワセミ通信 No.90 (PDF). Lake Sai [ja] Nature learning Center. Toda, Saitama. Retrieved 2019-10-31.
  17. ^ Imaizumi, Y. (1970), p. 140.
  18. ^ Kuroda, Nagamichi (June 1957). "Nihon-san komogura no ashu-mei henkō ni tsuite" 日本産コモグラの亜種名変更について [A new name for the lesser Japanese mole]. 哺乳動物学雑誌 [Journal of the Mammalogical Society of Japan]. 1 (3): 74.
  19. ^ Kuroda, Nagamichi (1954). "食虫目" [Insect-eating Mammals INSECTIVORA]. Nihon jūrui zusetsu 日本獣類図説 [A monograph of the mammals of Japan]. Sogensha. p. 144. 中古有胎盤類にその源を置き,一方は齧歯目に,他は食肉目に,そして他の一枝はこの食虫目となる。双角或は重複状子宮と盤状で脱落生の胎盤とを有する。睾丸は会陰部内に留まり,陰嚢はない
  20. ^ Kuroda (1954) generalizes this for the now disused Insectivora order, which he divides into the "no appendix" Lipotyphla sub order and "with appendix" Menotyphla. Quote: "睾丸は会陰部内に留まり,陰嚢はない".[19]
  21. ^ Imaizumi, Y. (1970), p. 143.
  22. ^ "Yama no mogura no seisoku jōkyō wo teiryōka: dojō seitaikei no kagi wo nigiiru chika seibutsu no seitai ni semaru" 山のモグラの生息状況を定量化 ～土壌生態系の鍵を握る地下生物の生態に迫る～ [Quantifying the status of habitation by moles in the mountains: closing in on the living habits of underground organisms that are key to soil ecology ｜国立大学法人 山形大学]. 国立大学法人 山形大学 (in Japanese). Retrieved 2025-03-09.
  23. ^ Yamasawa, Tai; Tomimatsu, Hiroshi. "Quantifying relative abundance of the lesser Japanese mole (Mogera imaizumii) in mountain forests: A comparison between natural broad-leaved forests and conifer plantations". Ecological Research. n/a (n/a). doi:10.1111/1440-1703.12548. ISSN 1440-1703.
  24. ^ Yamasawa, Tai; Takagi, Toshihito; Kaneko, Shingo (2023). "Azuma mogura (Mogera imaizumii) no hanshoku seitai kaimei ni muketa maikuro sateraito mākā kaiseki no yūyōsei" アズマモグラ（Mogera imaizumii）の繁殖生態解明に向けたマイクロサテライトマーカー解析の有用性 [Utility of microsatellite markers for determining reproductive traits in lesser Japanese moles (Mogera imaizumii)]. 哺乳類科学 [Mammalian science]. 63 (2): 179–184. doi:10.11238/mammalianscience.63.179.
  25. ^ "Azuma mogura no oyako hantei: andāguraundo na mogura no kōhai jijyō wo iden kaiseki de kaimei e" アズマモグラの親子判定 ～アンダーグラウンドなモグラの交配事情を遺伝解析で解明へ～. Yamagata University (in Japanese). Retrieved 2025-03-09.
  26. ^ a b c d e "Azuma mogura" アズマモグラ. Nihon no Red Data kensaku system 日本のレッドデータ検索システム. 2018–2023. Retrieved 2025-07-07.
  27. ^ Kyotofu Red Data Book 京都府レッドデータブック Azuma mogura アズマモグラ (2015)

Sources cited

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