Evidence of a Late Birth for the Raccoon

Berard, Edward V.

doi:10.1093/jmammal/33.2.247-a

Cited by 5 publications

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“…However, a second estrus after mating season or late litters have been reported [3,4,10,20,21]. The physiological details of the second estrus in female raccoons are not known, but Gehrt and Fritzell [4] reported that females were consorting with males an average of 9 days (n=6, range=6-14days) after the loss of their first litters.…”

Section: Discussionmentioning

confidence: 99%

“…However, late-born pups have been reported in Hokkaido [2]. In North America, it has been reported that some females that failed to get pregnant or lost their pups can reproduce again after April, although they basically reproduce once a year during the mating season [3,4,20,21]. Although this flexibility in female raccoon reproduction has been reported, male reproductive characteristics are not well known.…”

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confidence: 99%

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Seasonal Changes in Spermatogenesis and Peripheral Testosterone Concentration in Raccoons (Procyon lotor) in Hokkaido

Okuyama

Shimozuru

Takahashi³

et al. 2012

The Journal of Veterinary Medical Science

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ABSTRAcT. Feral raccoons (Procyon lotor) have been increasing in number since 1979 and are currently subject to pest control in Hokkaido. One of the reasons for the increase in numbers is thought to be the high reproductive potential of raccoons, but little is known about their reproduction. The main aim of this study was to clarify seasonal changes in spermatogenesis and peripheral testosterone concentration of raccoons in Hokkaido. In the present study, external characteristics and histology of the testis and epididymis and the plasma testosterone concentration were investigated in 68 feral, male raccoons culled for pest control and once a month in one live, captive male. The feral males exhibited seasonal changes in spermatogenesis, showing active spermatogenesis in autumn, winter and spring (October−June) with noted spermatogenesis and inactive spermatogenesis in summer (July−September) with lower mean levels of spermatozoa in the cauda epididymis. Even in the inactive period, spermatozoa were observed in about half of the individuals (14/26); therefore, individuals producing spermatozoa existed every month throughout the year. Testosterone concentrations were significantly high in the winter mating season. In the captive male, the testosterone concentrations were low from June to August, and spermatozoa could not be observed from July to September. These results suggest that raccoons exhibit seasonality of reproduction, but the time and duration of spermatogenetic decline varies widely among individuals. This individual variation in the inactive period is a feature of male raccoon reproduction and is unique among seasonally breeding mammals.

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

Seasonal Changes in Spermatogenesis and Peripheral Testosterone Concentration in Raccoons (Procyon lotor) in Hokkaido

Okuyama

Shimozuru

Takahashi³

et al. 2012

The Journal of Veterinary Medical Science

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“…On the other hand, reports of late litters produced from August to October are common at lower latitudes including West Virginia, southwestern Georgia, northwestern Florida, and southern Texas [3,8,19]. These late litters are conceived in a second mating period, which involves coming into a second estrus after losing a previous litter or failing to produce a litter from the first mating period [8].…”

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confidence: 99%

Difference in Age at First Conception between Early and Late Litters of Feral Raccoon (Procyon lotor) in Kanagawa Prefecture

Kato

Uno

Fujioka

et al. 2012

The Journal of Veterinary Medical Science

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ABSTRACT. Due to the long parturition period of raccoons, we assumed that age at first conception of late born females was later than that of early born females. From March 2005 to September 2008, 201 females estimated to be younger than 24 months were separated into early-and late-born groups on the basis of their estimated birth month (to the nearest 2 months), and parous status and body mass index (BMI) were examined. Age at first conception of late-born females (over 18 months old) was estimated to be later than that of early-born females (over 12 months old). The average BMI in early-born individuals at 12 months old might have affected their ability to conceive because of body fat deposition.

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“…2). Late litters in summer are reported at several locations in North America, at more northern latitudes than Kamakura [2,3,6], however, only the study at southern Texas confirmed a bimodal distribution in the parturition periods of raccoons [7]. The climate of Kamakura is different from the subtropical climate of southern Texas, and in this study, it was not possible to examine how various factors influence the distribution of raccoon parturition periods.…”

Section: Parturition Periodsmentioning

confidence: 68%

“…In North America, Gehrt [6] discussed that parturition of raccoons typnically occurs in April at northern latitudes such as Illinois (N40) [27], and sometime later at southern latitudes: West Virginia (N38), until August [3]; southwestern Georgia and northwestern Florida (N31), until early October [21]; and southern Texas (N28), until September [7].…”

Section: Parturition Periodsmentioning

confidence: 99%

Reproductive Characteristics of Feral Raccoons (Procyon lotor) Captured by the Pest Control in Kamakura, Japan

et al. 2009

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ABSTRACT. In order to examine reproductive characteristics of feral raccoons in Kamakura, 335 raccoons were collected from March 2005 to March 2007. Raccoons were classified into five age classes: Class I, less than 5 months old; Class II, 5-11 months; Class III, 12-17 months; Class IV, 18-23 months; and Class V, over 23 months old. Females were examined for their age specific pregnancy rate and litter size. To determine when raccoon births occur in the region, birth months of fetuses were estimated by the fetal growth rate, and birth months of Class I individuals were examined by tooth eruption. From fetuses of 18 pregnant females and 47 Class I individuals, it was found that the raccoon births occur from February to October. Of 163 females examined, all of Class I-II females were nulliparous. Pregnancy rate was 47.6% in Class III females, which was significantly lower than 75.0% in Class IV and 78.1% in Class V. The litter size of fetuses ranged from 2 to 5, and 3.9 on average; and that of placental scars ranged from 1 to 7, 3.8 on average. Our findings suggest that parturition of raccoons is a bimodal distribution and age at first parturition may occur between 12 and 17 months old. In order to reduce the raccoon population successfully, females of all ages should be captured throughout the year.KEY WORDS: litter size, parturition, pregnancy rate, Procyon lotor, raccoon.J. Vet. Med. Sci. 71(11): 1473-1478, 2009 Reproductive characteristics have an influence on the population dynamics in wild mammals. Breeding season, pregnancy rate, and litter size are often useful data for wildlife management. Reproductive characteristics should also be investigated for monitoring of the alien species control program.The raccoon (Procyon lotor) is native to North America, and considered as invasive alien species in Japan. The first report of raccoon naturalization was made in 1962 and the animals are known to have escaped from a zoo in Inuyama, Aichi [1]. The feral raccoon has been distributed to all prefectures of Japan because of naturalization by escapes from captivity and intentional releases [9][10][11]17]. In Kamakura, raccoon naturalization was identified in 1988 [23], and the feral raccoons have been captured to control the damage of invading houses [11]. Kanagawa Government formulated raccoon control program in 2006 [15], with the basis of the Invasive Alien Species Act in 2005. Reproduction of raccoons in North America has been studied extensively [18,20,24,25,27,28], and reproductive characteristics have been considered to vary in the different distribution [5,6,24,30]. In recent years, several studies of feral raccoon reproduction have been published in Japan [2,16,29]. Like in North America, not only adults but also yearlings of the feral raccoon were reported to mate in breeding season [2,29]. In Kanagawa, although many raccoons have been captured by the pest control actions, female reproductive characteristics are not well known. Kanagawa raccoon control program was formulated on the basis of previous studies t...

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Evidence of a Late Birth for the Raccoon

Cited by 5 publications

References 0 publications

Seasonal Changes in Spermatogenesis and Peripheral Testosterone Concentration in Raccoons (<i>Procyon lotor</i>) in Hokkaido

Seasonal Changes in Spermatogenesis and Peripheral Testosterone Concentration in Raccoons (<i>Procyon lotor</i>) in Hokkaido

Difference in Age at First Conception between Early and Late Litters of Feral Raccoon (<i>Procyon lotor</i>) in Kanagawa Prefecture

Reproductive Characteristics of Feral Raccoons (Procyon lotor) Captured by the Pest Control in Kamakura, Japan

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