Timing of Puberty and Its Relationship with Body Growth and Season in Male Raccoons (Procyon lotor) in Hokkaido

Minami W. OKUYAMA; Michito SHIMOZURU; Go ABE; Mariko NAKAI; Mariko SASHIKA; Ken-Ichiro SHIMADA; Nobuhiro TAKAHASHI; Daisuke FUKUI; Ryohei NAKAMURA; Toshio TSUBOTA

doi:10.1262/jrd.2012-198

Original Articles

Timing of Puberty and Its Relationship with Body Growth and Season in Male Raccoons (Procyon lotor) in Hokkaido

Minami W. OKUYAMA, Michito SHIMOZURU, Go ABE, Mariko NAKAI, Mariko SASHIKA, Ken-Ichiro SHIMADA, Nobuhiro TAKAHASHI, Daisuke FUKUI, Ryohei NAKAMURA, Toshio TSUBOTA

Author information

Minami W. OKUYAMA
Graduate School of Veterinary Medicine, Hokkaido University, Hokkaido 060-0818, Japan
Michito SHIMOZURU
Graduate School of Veterinary Medicine, Hokkaido University, Hokkaido 060-0818, Japan
Go ABE
Graduate School of Letters, Hokkaido University, Hokkaido 060-0810, Japan
Mariko NAKAI
Graduate School of Letters, Hokkaido University, Hokkaido 060-0810, Japan
Mariko SASHIKA
Graduate School of Veterinary Medicine, Hokkaido University, Hokkaido 060-0818, Japan
Ken-Ichiro SHIMADA
Graduate School of Letters, Hokkaido University, Hokkaido 060-0810, Japan
Nobuhiro TAKAHASHI
Asahikawa Municipal Asahiyama Zoological Park & Wildlife Conservation Center, Hokkaido 078-8205, Japan
Daisuke FUKUI
Asahikawa Municipal Asahiyama Zoological Park & Wildlife Conservation Center, Hokkaido 078-8205, Japan
Ryohei NAKAMURA
Asahikawa Municipal Asahiyama Zoological Park & Wildlife Conservation Center, Hokkaido 078-8205, Japan
Toshio TSUBOTA
Graduate School of Veterinary Medicine, Hokkaido University, Hokkaido 060-0818, Japan

Keywords: Procyon lotor, Puberty, Raccoon, Reproduction, Spermatogenesis

JOURNAL FREE ACCESS

2013 Volume 59 Issue 4 Pages 361-367

DOI https://doi.org/10.1262/jrd.2012-198

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Abstract

The raccoon (Procyon lotor), indigenous to North America, has naturalized in Japan as an invasive alien species, having been introduced into the country in the 1970s. In Hokkaido, the northernmost island of Japan, feral raccoons have been increasing in number and spreading throughout the island. The age at the onset of puberty for raccoons is important for estimating individual lifetime reproductive success and population growth. The present study investigated the timing of and potential factors affecting the onset of puberty in male raccoons in Hokkaido. External characteristics and histology of testes were studied in 151 male feral raccoons and in 1 captive juvenile. For the majority of feral yearling raccoons, prepubertal development began in May, and spermatozoa production began in October prior to their second mating season. However, some larger juveniles attained puberty during the juvenile period. The captive juvenile, which was fed throughout the winter, attained puberty only 11 months after birth. These results suggest that if male raccoons can achieve enough body growth before the first mating season, puberty can be attained early. In both juveniles and yearlings, spermatozoa production was only observed after autumn. This timing coincided with the recrudescence of seasonally active spermatogenesis in adult males. Therefore, attaining puberty in male raccoons appears to require both adequate body nutrient development and several environmental factors that control seasonal testicular changes.

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