Abstract This study investigated the reproductive behaviors of Formosan macaques (Macaca cyclopis) from July 2000 to July 2002 with 608 field hours in Mt. Lonvegity. I followed troops C and Cd that resulted from a fission of troop C in Dec. 2000. During these two mating seasons, 19 sexually mature males and 19 females were involved in 188 mounting/thrusting series. These included 139 single and 49 multi-mounting thrusting series. The peak frequency of copulation was in Dec. in both years with means of 1.34/hr and 0.94/hr. However, the maximum number of males and females involved were in Nov and Nov~Dec.. with 18 (9M9F, 2001) and 22 (12M10F, 2001) individuals. The residency and ranks of males influence their copulation strategies. Alpha males performed over half of the multi-mount copulations (55.1%), followed by non-troop males and other troop males (each, 22.45¢M). On the other hand, the highest proportion of single mount copulations were from OTM (38.13%)¡CBiting and copulation calls occurred more frequently in multi-mount than in single mount copulation. The duration of thrust was longest in the last mount of multi-mount copulation series (10.9 sec ¡Ó5.4, n=45), next in single mount (8.16 sec ¡Ó4.2). Male dominant rank influenced the occurrence of consortships between heterosexual pairs. Nearly all of consortships observed were performed by troop males (94/105 = 89.4%), NTM just 10.48¢M(11/105 = 10.48%)¡CHigh-ranking males guarded estrous females and interfered low-ranking males' copulation. The later used sneaky mating during the absence of dominant males or in the peripheral part of a social troop with poor visibility.¡C Troop C was dominant to troop Cd in habitat utilization and intertroop interaction. Troop C often chased troop Cd away (78.3%) or troop C withdrew voluntarily (21.7%). After the troop fission, the peak of monthly frequency of copulation in Cd was higher than that in troop C (two mating seasons: 3.33/hr versus 1.44/hr, 2.80/hr versus 0.74/hr). The birth rates of these two troops both increased from 2001 to 2002 (C: 37.5% to 81.3%; Cd: 50.0% to 100%)¡C

Soil in the Mt. Longevity, Taiwan, eaten by Formosan macaques, was analyzed to determine the possible stimulus or stimuli for geophagy. I attempted to test the mineral supplementation hypothesis and to document macaques using particle size. I studied macaques soil-eating behavior from July 2000 to April 2002 in the Mt. Longevity, Taiwan, and analyzed soil samples eaten and uneaten by Formosan macaque for physical-chemical properties and geochemistry in the study area. The results show that samples of soil eaten contained relatively high iron ( 3.6% ) and aluminum ( 16.0% ). However, the concentration of samarium was significantly lower in soil from samples eaten than in the random samples. No difference in concentration of the remaining fifteen elements ( magnesium¡Bcalcium¡B chromium¡Bmanganese¡Bcopper¡Barsenic¡Bstrontium¡Bbarium¡Blanthanum¡Bcerium¡Bneodymium¡Bytterbium¡Bphosphorous¡Bsulfate¡Bchlorides ) and Nitrate nitrogen was found between these two groups of soil samples. Geophagy occurred at a high rate of 0.31 monkey per hour with an elevated frequency in the reproduction season. The density of geophagy has been estimated as 1.6¡Ñ103 individuals per km2 . Frequency of male geophagy were recorded highest in September. Frequency of Females eating soil was recorded mainly between February and April. The ingested soils were significantly richer in clay than control soils. This study supports the hypothesis that mineral supplementation is a major factor for Formosan macaque engaging in geophagy.