Most of the situations to which optimal foraging theory has been applied can be divided into the following four categories: (1) optimal food choice; (2) optimal food patch choice; (3) optimal time allocation to different food patches; (4) optimal patterns and speed of movements (Pyke et al., 1977). I have reviewed the ways in which the first three problems have been tackled thus far in primate feeding ecology. I have also reconsidered the foraging behaviour of the wild Japanese monkeys that inhabit Kinkazan Island, Miyagi Prefecture, in terms of net rate of energy intake which is usually employed as a measure in analyses of optimal foraging theory. I found that there was no significant tendency for the monkeys to spend more time in feeding on food items that are associated with more rapid energy intake. Furthermore, monkeys chose the higher-quality food patch (i. e., where the feeding speed was higher) and fed there, but showed no significant tendency to feed for a longer time in the higher-quality patch. I have discussed ecological factors other than the net rate of energy intake and social factors that influence these results. Finally, I have presented a summary of the general foraging strategies of Japanese monkeys that I have studied thus far.

View full abstract

The daily energy intake of provisioned Japanese monkeys was studied, particularly in the forest by focal animal sampling method. The study was conducted at Takasakiyama throughout a day for 5 days in March-April 1985 and 4 days in February 1986.
The average metabolic body size (kg^3/4) of randomly chosen focal animals was estimated to be 4.12kg^3/4 (March-April) and 3.66kg^3/4 (February). The daily enegy intake from natural food in the forest was 139.7kcal/kg^3/4 (March-April) and 75.0kcal/kg^3/4 (February). While at the artificial feeding ground, it was 98.7kcal/kg^3/4 (March-April) and 102.6kcal/kg^3/4 (February). Daily digestible energy was calculated as 83.8kcal/kg^3/4 from natural food and 85.9kcal/kg^3/4 from the artificial food in March-April, and, 41.3kcal/kg^3/4 and 89.3kcal/kg^3/4 in February, if digestibility of natural food in March-April and February (leaves occupied 60%) was calculated as 60% and 55% respectively, and that of artificial food was 87%. Daily energy consumption was calculated to be 98.7kcal/kg^3/4 (March-April) and 92.5kcal/kg^3/4 (February) from activity record. Daily excessive energy was estimated to be 71.0kcal/kg^3/4 (March-April) and 38.1kcal/kg^3/4 (February).
The daily digestible energy was more than the daily energy consumption in March-April as well as in February. This study suggests that excessive energy intake is used for growth, reproduction and activities for Japanese monkeys at Takasakiyama.

View full abstract

A method for the population estimation of Japanese macaques, Macaca fuscata, was studied for conservation. (1) A significant correlation was found between the increase of the distribution range of Japanese macaques and the decrease of the broadleaf forest by analysis of “Population Census and the Second Basic Survey on the Natural Environment(PCSBSNE)”and “the Statistics of Forestry”. The natural broadleaf forest range was deduced as a major limiting factor of the macaque population. (2) The fact that the group size and the size of the undisturbed broadleaf forests (deciduous or evergreen) within its home range are correlated each other was applied as the preliminary formula to estimate the total population of Japanese macaques. That is, the population of Japanese macaques in each forest was calculated from the area of the deciduous and evergreen forests separately where distribution of monkey troops is recorded. (3) The preliminary formula was modified by the comparison with the actual observation in several sample areas. (4) Finally, areas in each vegetation type throughout Japan were measured from PCSBSNE and the total number of Japanese macaques in their natural habitat was estimated to be 114, 431.
For drawing up a more precise formula, other factors influencing the population size is needed to find through exact observations at more sample areas. For the wildlife management of Japanese macaques, periodical assessment of the Japanese macaque population and the habitat quality are required.

View full abstract

Blood group A, B and H antigens on red cells of non-human primates were examined by direct hemagglutination reaction, antibody absorption and heat elution tests. ABH substances on red cells from prosimians, New World and Old World monkeys were detected only by elution test with human anti-A, anti-B and chicken immune anti-H antibodies and their activities were equivalent to those from variants of human group A and B. Red cells of apes except gorilla were agglutinated with anti-A, -B and -H from human antisera, monoclonal antibodies and lectins, and their activities corresponded to the activities of human intermediate types of blood group A and B. Red cells of gorilla reacted weakly with human antisera, but failed to react with monoclonal antibodies, and such reactivities of red cells were corresponded to those of human subgroups.
In various species of non-human primates, as in human, blood group specific anti-A and/or -B antibodies were present in the serum according to Landsteiner's rule. Water soluble and chloroform-methanol soluble extracts from digestive tissues of prosimians, New World and Old World monkeys showed the ABH-activities demonstrated on red cell. Extracts from submaxillary glands, stomach and upper part of small intestine showed stronger activities than lower part of intestine, and were almost equivalent to those of tissues from human secretors.

View full abstract

Crab-eating monkeys (Macaca fascicularis) inhabiting Angaur Island, in the Republic of Palau, Micronesia, are said to be descendents of animals brought to the island about 80 years ago (Poirier and Smith, 1974). Field sampling was performed in November and December 1986 for somatometry, clinical inspection of hematological and parasitological characteristics, and genetic assessment of the monkeys' origin, in order to define their biological characteristics.
In total, samples from 70 individuals were obtained in the field. Physically the island monkeys were smaller than animals that originated in Indonesia. A color variant, with hairs lacking brown shading, was observed in three of the captured animals. Hematological examination revealed that the mean number of leukocytes (WBC) was high and the mean erythrocyte count (RBC) and hematocrit value (Ht) were low. The appearance of helminth was so rare that only Streptopharagus sp. was found. Six different alleles were detected at the transferrin locus. The mean heterozygosity of the population was estimated to be 10.2%, suggesting a relatively high degree of genetic variability.

View full abstract

The representational ability of chimpanzees was tested and compared with that of humans in terms of two aspects: short-term memory reproduction and mental rotation. In the test of short-term memory reproduction, a chimpanzee and adult humans were trained to reconstruct 84 three-element figures after various delay intervals up to 32sec. The chimpanzee maintained performances slightly better than humans under all delay conditions. However, different from humans, accuracy of reconstruction of meaningful figures which stood for food was not higher than that of meaningless ones. In the test of mental rotation, another chimpanzee and adult humans matched rotated figures from samples. Humans showed a monotonous increase in the reaction time of matching response as a function of the rotational angles up to 180 degree between sample and comparison stimuli, while the chimpanzee showed a peak of reaction time for rotational angles of around 90 degree. These results suggest that although recent sutdies of primate cognition has stressed the parallel of nonhuman primates and humans, some fundamental aspects of representational ability are different in these species. The chimpanzees seem to have the difficulty in spontaneously integrating the information given in different contexts which are related to each other.

View full abstract