Home Range Size and Overlap of the Small Nocturnal Schlegel’s Japanese Gecko (Gekko japonicus), Introduced into a City Park in Korea

Studying the home range of an organism is important in understanding its ecology. Due to being cryptic, few studies have been conducted on the home range studies of small, nocturnal geckos. We conducted radio-tracking surveys for 23 individuals to estimate the home range size and home range overlap of the Schlegel’s Japanese gecko(Gekko japonicus) previously introduced into a suburban city park. Individuals were commonly found in artificial structures(buildings and accessory structures) and on nearby natural trees. Daily moved distance was positively correlated with home range size. Minimum convex polygon(MCP) home range was 97.8 m^2 for females and 99.5 m^2 for males, on average. Gekko japonicus moved farther daily distances and used wider MCP and Kernel 95 home ranges in breeding season compared to non-breeding season, while the size of Kernel 50 home range did not differ between seasons. Both daily moved distance and home range size were not significantly different between sexes. In the breeding season, MCP and Kernel 50 home ranges of each gecko overlapped with 32.4% and 13.8% of remaining geckos, respectively. Our results not only show that 1) G. japonicus uses both artificial structures and adjacent natural trees as microhabitat, but also suggest that 2) G. japonicus is non-territorial, but has a core habitat that is shared with few other individuals, and 3) the reproductive system of G. japonicus is polygamous.

Habitat Use, Home Range, and Hibernaculum of the Mongolian Racerunner, Eremias argus (Lacertidae, Reptilia) in a Coastal Sand Dune in South Korea

Information on habitat use is critical in sizing protected areas for endangered reptile species. To investigate habitat use, home range, and hibernaculum of the endangered Mongolian Racerunner(Eremias argus), we radio-tracked 40 specimens in a coastal sand dune in South Korea. Of the 163 locations recorded during the breeding season, 150(92.0%) were in grass sand dunes, and the rest(8.0%), all associated with the same lizard, were in shrub sand dunes. All of the 123 locations recorded during the non-breeding season were in grass sand dunes. No lizards were found in the grasslands abutting the dunes. The four lizards with identifiable hibernation sites were found under an average of 17.8 cm of sand and were all located in grass sand dunes. The lizards moved approximately 5 m daily and used 162 m2of home range(computed by minimum convex polygon, MCP) during the breeding season, and they moved approximately 2 m and used 68 m2of home range during the non-breeding season. However, the mean daily moved distances and MCP home ranges were not statistically significantly different between the seasons or between males and females. Our results suggest that in coastal sand dunes, E. argus uses grass sand dunes as its main habitat throughout the year. This finding could be used to determine the appropriate habitat size and to designate for the conservation of this endangered species.

Spatial Ecology of Translocated and Resident Amur Ratsnakes(Elaphe schrenckii) in Two Mountain Valleys of South Korea

The translocation of snakes has been viewed as a useful tool to augment declining populations and to mitigate human-wildlife conflicts, even though released snakes often exhibit relatively high mortality. We radio-tracked 13 Amur Ratsnakes （Elaphe schrenckii） in the Woraksan National Park in South Korea from July 2008 to May 2009. Two of these snakes were residents, and 11 had been illegally captured in areas remote from the study site and were donated by the park office. During the study period, six of the translocated snakes were lost： two were killed by predators, one died of unknown causes, and the radio signals of three of the snakes were lost. In the field, the ratsnakes laid eggs in early August, moved into hibemacula in late November, and moved away from the hibemacula in mid-April. Compared to the resident snakes, five of the translocated snakes traveled approximately 1.3 times farther per week, and the home ranges of the translocated snakes were three to six times larger than those of the resident snakes. In addition, the translocated snakes were found underground more frequently than the resident snakes. The management recommendations resulting from this study will guide biologists and land use managers in making appropriate decisions regarding release sites and the use of gravid females in the translocation of this endangered ratsnake.

Can an Invasive Prey Species Induce Morphological and Behavioral Changes in an Endemic Predator? Evidence from a South Korean Snake(Oocatochus rufodorsatus)

Introduction of an invasive prey species into an ecosystem may affect an endemic predator＇s fitness by altering the prey-predator system. Successful adaptation may allow the endemic predator to eat and control the invasive species, while unsuccessful adaptation may result in extinction of the predator. We examine the possible effects of the invasive North American bullfrog （Rana [Lithobates] catesbeiana） on the endemic Red-backed rat snake （Oocatochus rufodorsatus） in South Korea. We do so by comparing the morphology and behavior of adult and hatchling snakes from bullfrog-exposed （Taean） and bullfrog-unexposed （Hongcheon） populations. Among the seven morphological characteristics investigated, relative tail length （tail length/snout-vent length） of both adults and hatchlings from Taean was significantly greater than that of adults and hatchlings from Hongcheon. Also, adult snakes from Taean had a signiifcantly shorter latency of ifrst tongue lfick in response to prey compared to adults from Hongcheon. This difference was not observed in hatchlings. In other snake species, a longer relative tail length and shorter latency of ifrst tongue lfick are known to improve foraging efifciency, and these characters may be adaptations ofO. rufodorsatus to prey on bullfrogs. This study provides preliminary evidence that the presence of an invasive prey species may cause morphological and behavioral changes in an endemic predator.

Report of a Dicephalic Steppes Ratsnake (Elaphe dione) Collected in South Korea

In this report, we describe morphological characteristics of a dicephalic Steppes Ratsnake （Elaphe dione） collected from the wild in 2011 in South Korea. The specimen has two heads and two long necks. Unlike normal individuals, the dicephalic snake has divided ventral scales under the necks of the bifurcated columns. The snout- vent length （SVL） and overall total length of the individual are shorter than those of normal snakes of the same age. Nevertheless, the counts of nine different scale types that are often used for classification are all within the ranges of normal individuals. As far as we know, this is the first detailed morphological description of a dicephalic E. dione in the scientific literature.

First Record of the Blue-banded Sea Krait(Laticauda laticaudata,Reptilia:Squamata:Elapidae:Laticaudinae)on Jeju Island,South Korea

We report the first recorded capture of a blue-banded sea snake（Laticauda laticaudata Linnaeus, 1758, Jobeuntti Kun Badabam in Korean） in South Korea based on one male specimen collected from Marado-ri, Seogwiposi, Jeju-do on 20 October 2016. The morphological features of the lateral nostrils, the much wider ventrals than adjacent dorsals, the horizontally undivided rostral, the two prefrontals, and the uniform black bands on the body indicate that the specimen is L. laticaudata. An analysis of the partial mitochondrial cytochrome b gene sequence indicated that the specimen fits well into the known L. laticaudata phylogenetic group, which confirms that the sea krait is L. laticaudata. Including this report, five species of sea snakes（L. laticaudata, L. semifasciata, Hydrophis platurus, H. cyanocinctus, and H. melanocephalus） have now been reported in Korean waters.