Rethinking Social Issues of Crop-feeding by Japanese Monkeys from Future Prospects of an Agri-community
~A Case Study of Nishimeya-village Animal Patrol in Shirakami Mountains~
Nishimeya Village (246.6km2) in Aomori Prefecture is one of depopulated agri-communities, located in the northeastern Shirakami Mountains, the northernmost Honshu, Japan. In this village, Japanese monkeys (Macaca fuscata) have damaged apples of principal crops there since the 1980s. The village office implemented a project of monkey-driving inviting urban volunteers, named “Nishimeya-village Animal Patrol (NAP)”. It implemented between August to November, growing and harvesting season of apples, in 2002 and 2003. The NAP has two purposes; 1) to protect crops against the monkeys, 2) to satisfy volunteers who desired to enjoy agri- and eco-tourism in Shirakami area, surrounded by the scenic forest, which was designated as the World Heritage. This study intends to analyze the effect of the NAP, considering 1) ecological influence of the monkey-driving on the troops and 2) social appraisals of the NAP by the villagers and volunteers. Consequently, the monkey-driving compelled their range to enlarge from 2.6km2 in 2001 (before the NAP) to 9.3km2 in 2002 (first season of it), 13.2km2 in 2003 (second season of it), using the 90% contour of fixed kernel method. This range expansion resulted in a decline of apple damage from 6.6 million yen in 2001 to 132 thousand yen in 2002, 110 thousand yen in 2003. This result was appraised by 83.0% in 2002 and 79.2% in 2003 of the villagers (questionnaire surveys; n=53 for 2002, n=53 for 2003). In addition, the volunteers highly approved the NAP as the tourism, provided them with comfortable farm-life in nature with plenty of wildlife. Regardless of high approvals by both villagers and volunteers, it is difficult to expect that the NAP persists in the years ahead because 74.2% of the farmers intend to retire from farmwork in the near future (n=56); therefore, the NAP may temporarily perform “social welfare” for the aged farmers.
EFFECTS OF FOOD CONDITIONS AND SOCIAL FACTERS ON FOOD PATCH USE IN JAPANESE MACAQUES
Most primate species use patchy-distributed food resources. Many patch models have been developed by assuming that animals respond only to food conditions including patch size, quality and inter-patch distance, which define their foraging efficiency. However, actual patch uses in several primate species do not follow these models. Most primate species form groups with strong social bonds. Social effects must play important roles on their patch uses, and should be considered along with food conditions. We quantified effects of food conditions, number of individuals in the food patch and social rank on patch uses in Japanese macaques (Macaca fuscata).
The study site was Kinkazan Island, northern Japan, which had no predator for monkeys. A wild group of Japanese macaques was studied, in spring and autumn of 2003 and 2004. We collected foraging data( residence time, food handling bout, number of food intakes) and social data( number of monkeys in the same tree, and social interactions)in every visit of food patches using the focal animal sampling method. Crown size, food coverage of food patches and number of neighboring food patches were measured as food conditions. For main food items in the study periods, these data were analyzed separately.
Food conditions and social rank did not show consistent effects on patch uses between food items. However, number of monkeys affected positively on residence time, handling bout and intake rate in most food items. Agonistic interactions between members during patch uses didn’t decrease intake rate in even low-ranking females. Thus, scramble and contest food competition would work limitedly on their patch use. Inter-group encounter did not occur. This study showed that there is a certain positive social effect on foraging efficiency in patchy-distributed food condition even when lacking predator and inter-group interaction.