A fossil identified as Orlitia borneensis was found from the river bottom of the Solo River in Sambungmacan, eastern Central Java, Indonesia. The sandy matrix attached to the specimen strongly suggests that it was eroded out from the Middle Pleistocene fluvial deposit on the river bank, as most of the assorted vertebrate fossils have been found from this area. Because two fragmentary fossils that were previously referred to this species from the Lower Pleistocene of Trinil lack diagnostic morphological characteristics, the specimen reported here is the first certain fossil record of the species from Java. The present findings suggest that O. borneensis had a wider distribution in the past, but the Java population would have become extinct by the end of the Middle Pleistocene.
In the Brumas Plantation, Tawau, eastern Sabah of Borneo Island, I examined stomach contents of three frog species that are apparently segregating in microhabitat and morphology; Limnonectes cf. kuhlii is riparian, very stocky and always staying near streams or pools; Amnirana niobariensis, with slim body and long limbs, is terrestrial, inhabiting bushes near small pools, and Polypedates macrotis is arboreal, possessing large digital discs, and is found on trees or tall grasses. These three frog species exhibited food partitioning, differing in the amount and size of foods. Young L. cf. kuhlii always had stomach content mass (SCM) up to 3% of body mass (BM), and had the largest average number of small food items. In adult L. cf. kuhlii, few individuals lacked stomach contents, and foods were generally larger than in young frogs. Many A. nicobariensis had no stomach contents, and those with foods usually possessed SCM <2% of BM. Most food items were small in length. Polypedates macrotis tended to take large foods, but many had empty stomachs. Limnonectes cf. kuhlii and P. macrotis exhibited the mean food length smaller than their mouth width. When all frogs were combined, ants occupied the largest portion of all the food items, followed by crickets or grasshoppers, beetles, and spiders in that order.
By forced vomiting of stomach contents, we examined the diet of Lithobates catesbeianus inhabiting the city region of Kyoto, central Japan. Among various animal taxa consumed, crustaceans, including Asellota and Oniscoidea in juveniles and introduced American crayfish Procambarus clarkii and native crab Potamon dehaani in adults, occupied the largest proportion in number. In volume, the crayfish and crab also comprised the larger part, and the rest was composed mainly of beetles, bugs, and centipedes. Food habits of L. catesbeianus from Kyoto are characterized by the following points: (1) the frog tends to take a smaller number of larger prey as its body size increases; (2) aquatic prey animals, especially crustaceans, seem to be more important than terrestrial ones; (3) feeding intensity seems to be constant throughout the active seasons, including the breeding season; and (4) vertebrates comprise only very small proportion of the diet, despite their apparent availability, strongly contrasting to previous studies in other localities. Effects of predation on native animals seem to be not very large at present.
We studied the longevity and growth pattern of the wild populations of invasive green anoles (Anolis carolinensis) in Chichi-jima Island, Japan. We estimated specimen age using skeletochronology and counted the number of lines of arrested growth (LAGs) on thin cross sections of femur bones. We observed from zero to five of LAGs for both male and female specimens. This indicated that the green anoles can survive at least five years in Chichi-jima Island. Body size increased with the number of LAGs, but the growth rate decreased when individuals had two LAGs. Our results suggest that the wild anoles might expend more energy for reproduction rather than for growth at this stage.
Feeding habits of snakes on Kinkasan Island, where potential food resources for snakes is limited, was investigated based on field surveys of six years. In total 280 snakes, which consisted of five species (Elaphe quadrivirgata, E. climacophora, Euprepiophis conspicillatus, Rhabdophis tigrinus, and Gloydius blomhoffii), were collected. A total of 168 prey items were recovered from the stomach contents of these snakes. The diet of R. tigrinus and G. blomhoffii exclusively consisted of a frog, Rana tagoi, which is the only amphibian species inhabiting Kinkasan Island. Diet of El. quadrivirgata was also predominantly comprised of Ra. tagoi (97.7%). Only endothermic animals were found in the stomach contents of El. climacophora and Eu. conspicillatus. Direct observations of feeding behavior and a broad range of body temperature of El. quadrivirgata indicated that during the breeding season of Ra. tagoi, this snake forages for frogs hiding in crevices of rocks immersed in cold running water of mountain streams. Our study demonstrated that, given the limited prey fauna on Kinkasan Island, two dietary generalists, El. quadrivirgata and G. blomhoffii, and one amphibian specialist, R. tigrinus, largely rely on the single frog species as major diet. High exploitation of Ra. tagoi by El. quadrivirgata would be attained by its unique foraging tactics that are characterized by a shuttling movement between hot basking rocks and cold streams for foraging.
We determined sequences of mitochondrial control region of 16 specimens of the leatherback turtles, Dermochelys coriacea, collected in the vicinity of Japan, and estimated stock origin of Japanese migrants. As a result, we found three haplotypes (JD1, 2, and 3) in these specimens, and 14 specimens possessed JD1. In comparison with previously reported sequences, JD1 and 2 were identical to a single haplotype endemic to West Pacific stock in New Guinea and Solomon Islands, whereas JD3 was identical to a haplotype nearly endemic to Malaysian stock. Our results indicate that most of the leatherbacks foraging around Japan originate in West Pacific stock, and a few may migrate from the Malaysian nesting population.
The Hong Kong newt (Paramesotriton hongkongensis) is a tropical stream-dwelling salamandrid native to Hong Kong and coastal areas of Guangdong Province, China, inhabiting small rocky hill streams and surrounding forests. It is categorized as “near threatened” on the IUCN Red List because of range-wide habitat degradation and vulnerability to over-exploitation for the pet trade. Nine novel polymorphic microsatellite markers were developed and characterized using Illumina paired-end shotgun sequencing. Number of alleles per locus ranged from 10 to 19 (median=14). Cross-species amplification was attempted in four species of Asian newt: Cynops ensicauda, Pachytriton granolosus, Paramesotriton chinensis, and Tylototriton shanjing, which included two species of conservation concern, with varying degrees of success. The nine novel markers can be used to quantify genetic variability among isolated populations and have potential forensic applications in a number of Asian newt species that are highly threatened by over-exploitation throughout their ranges.
An unusual triploid individual (3N=42) was found in a population of Rana neba in nature. The individual had triplets of 14 chromosomes, which are apparently identical to those of diploid R. neba. This strongly suggests that this individual is autotriploid, although the mechanism of its emergence remains an open question.
Most of metamorphosed terrestrial frogs feed only on moving organisms and rarely exhibit scavenging behavior in nature. We here report a case of scavenging by the Japanese Rice Frog, Fejervarya kawamurai, which fed on a dead Black-spotted Frog, Pelophylax nigromaculatus at the edge of paddy field in central Japan. This observation is the first case of Fejervarya, feeding on a dead animal in nature and is an important addition to the cases of this unique behavior, which has been reported only for limited number of anuran species so far. In contrast, the behavior is more often reported for frogs in captivity, and F. kawamurai may be a useful species for examining scavenging behavior in post metamorphic anurans.
Foraging behavior of a diurnal gecko, Lygodactylus tolampyae, was observed during the night in the field in Ankarafantsika National Park, Madagascar. An adult L. tolampyae was observed to stay near the nest of an ant, Aphaenogaster swammerdami. The gecko attacked a worker ant carrying a pupa and ate only the pupa by robbing it from the worker. This observation suggests that typically diurnal geckos may shift foraging time to the night under natural conditions.