Variation in the nocturnal foraging distribution of and resource use by endangered Ryukyu flying foxes (Pteropus dasymallus) on Iriomotejima Island, Japan

Abstract

The nocturnal distribution and resource use by Ryukyu flying foxes was studied along 28 transects, covering five types of habitats, on Iriomote Island, Japan, from early June to late September, 2005. Bats were mostly encountered solitarily (66.8%) or in pairs (16.8%), with a mean linear density of 2.5 ± 0.6 bats/km of transect/night. Across the island, however, bat densities were distributed non-randomly among transect-nights, not correlated with transect length, and showed a slightly clumped distribution (variance/mean = 3.3). Outskirt trails contributed higher values to the relative importance of bat abundance, but the highest mean abundances occurred mostly at village sites on the west coast, which on average devoted only a quarter of their land area to agriculture/husbandry compared to those on the east coast. This supports our prediction that higher bat abundances are found in areas with less anthropogenic interference and more forest. Among habitats, the mean total abundance and density were lower in cultivated areas than in villages and inland forests. Bat perches in cultivated areas were also lower, and were in correspondence with lower shrub and canopy heights, and less canopy coverage. Flying fox abundance was correlated moderately with the heterogeneity of the tree composition, and strongly with the density of major fruiting trees. Thirty-nine species of plants and some animal items were used by Ryukyu flying foxes, including at least 31 species of fruits, 13 species of flowers, and leaves of seven species, with 14 species new to the record. Ficus septica and F. variegata were the most frequently encountered and dominant items in both fecal and rejecta/dropped samples, followed mostly by other figs and mulberries in the former, but by larger-seed non- Moraceae plants in dropped samples. Our results suggest that for conservation of flying foxes undisturbed forests providing an adequate resource basis are of major importance.

Public awareness and perceptual factors in the conservation of elusive species: The case of the endangered Ryukyu flying fox

“…3). 36 37 When suggested the adjectives ''Interesting'' to describe the Ryukyu flying fox, the distribution of the scores proved 38 roughly uniform (mean 2.47, s.d. 1.77).…”

“…Once more, the prevalent reply (68%) was ''I do not know'' (DNK). Furthermore, 21% believed that flying foxes were not 38 damaging crops, leaving only 11% aware of this fact. 39 40 As mentioned earlier, all the questions discussed from this point forward were submitted to the respondent after 41 requesting from him to read a summary about P. dasymallus (incl.…”

“…Lastly, 36 agriculture represents an important sector of activity for Ishigaki, resulting in the island's arable land being covered mainly 37 with sugarcane, pineapple, and banana plantations. 38 Our target population consisted of all adults residents. We decided to exclude foreign nationals because they represented 39 a negligible proportion of the population (less than 0.5%).…”

“…35 The amplitude of the decrease (about a quarter of the value) in comparison with the reduction in good could be a interpreted 36 as a sign of relatively low valuation of P. dasymallus conservation. Based on the numerical estimates of these WTPs, one 37 could conclude that people value three times more the protection of crops than the conservation of P. dasymallus (the latter 38 reaching then only a WTP of about 300 yen/household/year). This would contrast with studies in other countries, which 39 generally show interest in environmental protection over economic gains (Clark and Wallace, 1998).…”

“…They are also grateful to Takuya Koizumi, Hideaki Nishizawa, and Takuji Noda 37 for their advices regarding the translation of the survey form. The present project was partly financed by a Postdoctoral Q8 38 Fellowship of the Japanese Society for the Promotion of Science.…”