Reproductive parameters of female Japanese macaques: Thirty years data from the arashiyama troops, Japan

Abstract

ABSTRACT. Over a 30-year period from 1954 to 1983, 975 live births were recorded for Japanese macaque females at the Iwatayama Monkey Park, Arashiyama, Japan. Excluding unknown birth dates, primiparous mothers gave birth to 185 infants (182 cases with age of mother known) and multiparous mothers gave birth to 723 infants (603 cases with age of mother known). The peak month of birth was May with 52.3% of the total births occurring during the period. Multiparous females who had not given birth the previous year did so earlier than multiparous females who had given birth the previous year and also earlier than primiparous females. Among the females who had given birth the previous year, females whose infant had died gave birth earlier than females who had reared an infant the previous year. The offspring sex ratio (1 : 0.97) was not significantly different from 1 : 1, and revealed no consistent association with mother's age. Age-fecundity exhibited a humped curve. The annual birth rate was low at the age of 4 years but increased thereafter, ranging between 46.7% and 69.0%, at between 5 and 19 years of age, but again decreased for females between 20 and 25 years of age. Some old females displayed clear reproductive senescence. The infant mortality within the first year of age was quite low (10.3%) and the neonatal (less than 1 month old) mortality rate accounted for 49.0o/o of all infant deaths. There was no significant difference between the mortality rates of male and female infants. A female's rank-class had no apparent effect on the annual birth rate, infant mortality, and offspring sex ratio. These long-term data are compared with those from other primate populations.

Reconsidering the null hypothesis: Is maternal rank associated with birth sex ratios in primate groups?

“…Symbols indicate studies from the same sites as follows. ࡗ, Amboseli, Kenya (13,18); OE, Davis, CA (14,43); ᮀ, Madingley, U.K. (15,31,36); F, Salem, Germany (21, 39); E, Cayo Santiago, Puerto Rico (19,26,27); ‚, Ketambe, Indonesia (47,48); छ, Rome, Italy (25, 41); s, Arashiyama, Japan (32,46). For other definitions, see the legend for Fig.…”

Maternal investment in sons and daughters in provisioned, free-ranging Japanese macaques (<i>Macaca fuscata</i>)

“…Simpson and Simpson, 1982); and some suggest similar investments in both sexes (e.g. Koyama et al, 1992). Thus, previous studies are highly inconsistent (Brown, 2001).…”

“…Provisioned Japanese macaques (Macaca fuscata) are useful to examine sex-biased maternal investment using various parameters based on large sample size because inconsistent, but interesting, results have been reported-a male-biased birth sex ratio among high-ranking females (Aureli et al, 1990), longer interbirth intervals after rearing daughters than after sons (Takahata et al, 1995), and no sex-biased maternal investment (Koyama et al, 1992). There are abundant data on reproduction and infant growth in a provisioned, free-ranging Japanese macaque population at Takasakiyama, in the southern region of Japan (Kurita et al, 2002(Kurita et al, , 2008.…”

Pregnancy Rate and Conception Date in a Wild Population of Japanese Monkeys

“…Many detailed investigations have been conducted on the reproductive parameters, including birth rate and time, of provisioned Japanese monkey troops [4,[6][7][8][10][11][12]. Since the nutritional status of individual animals can be improved by artificial feeding, substantial changes have been observed in the reproductive parameters of provisioned troops [7,11].…”

“…Koyama et al [6] compared delivery dates in the Arashiyama troop by age and pregnancy history. Subsequently, they found that 4-year-old primiparous monkeys had later delivery dates (mean delivery date in midJune) than monkeys aged 5 or more years (mean delivery date in late May).…”