Shi-Ryong Park

Multiple Insemination and Reproductive Biology of Hynobius leechii

Combining knowledge of breeding dynamics in natural populations of a given species with behavioral data from laboratory studies is essential in gaining an understanding of sexual strategies (Verrell and Halliday, 1985). In this paper, we use a combination of laboratory and field studies to examine reproduction in Hynobius leechii, a primitive salamander from Korea that exhibits external fertilization.

Skeletochronological Age Determination and Comparative Demographic Analysis of Two Populations of the Gold-spotted Pond Frog (Rana chosenica)

To obtain demographic information on threatened gold-spotted pond frog (Rana chosenica Okada, 1931) populations, we determined the ages of 45 male and 13 female frogs (20 males and 9 females from Cheongwon and 25 males and 4 females from Tae-an) and compared the age structures and growth patterns of the two populations in 2006. The snout-vent length (SVL) and body weight of female frogs were greater than those of male frogs in both populations. Male frogs` ages ranged 2 to 7 years old and females` ages ranged 3 to 6 years old. In both populations, 4 years old male frogs were the most abundant age-sex class. The age structures of the two populations were significantly different and the growth coefficients of male frogs from the Cheongwon population were greater than those from the Tae-an population. The mean age of males from the Tae-an population was higher than that from the Cheongwon population. However, the SVL and body weights of male frogs were not different between two populations and there was no difference between the two populations in the mean male SVL at any age. The results could increase our understanding of the life-history of this threatened frog and may be useful in conservation planning.

Sexual Differences in Post-Hatching Saunders's Gulls: Size, Locomotor Activity, and Foraging Skill

Various selection pressures induce the degree and direction of sexual size dimorphism in animals. Selection favors either larger males for contests over mates or resources, or smaller males are favored for maneuverability; whereas larger females are favored for higher fecundity, or smaller females for earlier maturation for reproduction. In the genus of Larus (seagulls), adult males are generally known to be larger in size than adult females. However, the ontogeny of sexual size dimorphism is not well understood, compared to that in adults. The present study investigates the ontogeny of sexual size dimorphism in Saunderss gulls (Larus saundersi) in captivity. We artificially incubated fresh eggs collected in Incheon, South Korea, and measured body size, locomotor activity, and foraging skill in post-hatching chicks in captivity. Our results indicated that the sexual differences in size and locomotor activity occurred with the post-hatching development. Also, larger males exhibited greater foraging skills for food acquisition than smaller females at 200 days of age. Future studies should assess how the adaptive significance of the sexual size dimorphism in juveniles is linked with sexual divergence in survival rates, intrasexual contests, or parental effort in sexes.

Age estimation by skeletochronology and advertisement call variation in the black-spotted pond frog (Rana nigromaculata)

Abstract Advertisement calls may contain information about the callers and the calling spot, which can be used during mate selection. The relationships between variations in advertisement call characters and age, snout-vent length (SVL), and water temperature were analyzed for the black-spotted pond frog (Rana nigromaculata). After recording the advertisement calls, we measured the SVL of the callers and the water temperature of the calling spot, then we collected a toe clipping from each of the 25 individuals recorded. The age of each frog was determined using the skeletochronological method. The frogs were two to eight years old and the asymptotic size was 6.3 cm when fitted to the von Bertalanffy growth equation. Age was not linearly correlated with SVL. In the analysis of 743 recorded advertisement calls from 25 individuals, the water temperature caused a decrease in males’ call duration with more pulse groups, each having higher pulse rates, irrespective of age and SVL. Older males produced calls with more pulse groups and shorter pulse-group duration, which led to increasing call durations irrespective of the water temperature. Larger males produced lower dominant frequency, irrespective of the water temperature. Advertisement calls of the black-spotted pond frog provide information about the quality of males and the manner in which females use this information during mate selection. In this study, we provide information on how frequency reflects male size while temporal characters reflect age.

Estimating Detection Probabilities and Site Occupancy Rates of Three Anuran Species Using Call Surveys in Haenam Gun, Korea

We investigated the distribution of three anuran species, Three-striped pond frogs (Rana nigromaculata), Bullfrogs (Rana catesbeiana), and Narrow-mouthed toads (Kaloula borealis), in an administrative district, Haenam Gun, Junnam Province, Korea using volunteer call surveys. Twenty-eight volunteer call surveyors were assigned to each survey plot. Call surveys on whether the species are present or not were conducted for 5 minutes between 30 minutes after sunset and the midnight on rice fields and ponds from 10 April to 28 August in 2005. Depending on species, call surveys were carried out at seven to 28 plots with average 8.4 to 10.7 visits per the plot. We calculated the detection probabilities and occupancy rates of the three species using four models with three covariates: temperature, humidity, and the amount of water at the habitat. The model average detection probabilities of three anuran species of R. nigromaculata, R. catesbeiana, and K. borealis were 0.53, 0.74, and 0.41 respectively, and the site occupancy rates of them were 0.93, 0.94, and 0.86 respectively. Our results indicate that R. nigromaculata, R. catesbeiana, and K. borealis are common in Haenam Gun.

How do young black‐tailed gulls (Larus crassirostris) recognize adult voice signals?

This study was conducted to find out how young black‐tailed gulls (Larus crassirostris) recognize adult voice signals after hatching. For the experiment, adult voice recorded in the natural environment was played back at controlled intervals and intensity (dB) to 15 young gulls that were artificially hatched in the laboratory. The chirirah call frequency of young gulls increased as the intensity of the mew call increased. The chirirah response of the control group was highest to the mew call at intervals of 1.8 s. The adult long call and alarm call also showed similar results to the mew call when the interval and intensity were manipulated similar to the mew call. Based on the results of this experiment, it is assumed that the young black‐tailed gulls recognize adult voice signals based on the simple structure of adult voice signals, that is, the interval and intensity of the voice.

Olfactory responses of male and female red‐spotted newts to sex pheromones from the opposite sex

Functional characterization of sex pheromones in olfactory responses is essential for the study of chemical communications in amphibians. Using Y‐maze olfactory preference tests, we have investigated the olfactory responses of male and female red‐spotted newts, Notophthalmus viridescens, to the crude extracts of the opposite sexs genial and cloacal pheromones. Both male and female cloacal pheromone extracts caused the opposite sex to initiate olfactory responses by leaving the starting area in the Y‐maze, but only subject males exposed to female cloacal pheromone extracts completed olfactory choice by entering the side arm of the Y‐maze which received the pheromones. For genial pheromone extracts, only female genial pheromone extracts induced initial olfactory responses from test males. Neither male nor female genial pheromone extracts made the opposite sex complete olfactory choice. Pre‐exposure of test females to male pheromone extracts increased the likelihood of initial olfactory responses. The latency for initial olfactory responses of test females that were previously exposed to male genial extracts was significantly shorter than that of control females.

A Case of Chaunocephalosis by Chaunocephalus ferox (Digenea: Echinostomatidae) in an Oriental White Stork, Ciconia boyciana, in Korea

We intended to describe a case of chaunocephalosis and morphological characteristics of its causative agent, Chaunocephalus ferox, recovered from an oriental white stork, Ciconia boyciana, in the Republic of Korea. An oriental white stork was referred to the Wildlife Center of Chungbuk in Korea in February 2014 for severe depression with cachexia and it died the next day. At necropsy, the stomach was severely expanded and 7 thick-walled nodules were observed in the upper part of the intestine. Although the stomach was filled with full of foreign materials, the intestine was almost empty. The nodules were globular and total 9 flukes were recovered. They were 8,030–8,091 μm in length and 3,318–3,333 μm in maximum width. Because the flukes had bulbous forebody with short narrow subcylindrical hindbody, 27 collar spines, and vitelline follicles not reaching to the posterior end, the specimens were identified as being C. ferox. The cyst formation induced thickening of the intestinal wall with narrowing of the lumen that could have contributed to the gastric impaction to the death of the host. This is the first described case of chaunocephalosis and its causative agent C. ferox found from an oriental white stork in Korea.

Inability of mate and species recognition by male Asian toads, bufo gargarizans

Abstract In recent years, we frequently observed miss‐matched pairs between male Asian toads, Bufo gargarizans, and bullfrogs, Rana catesbeiana, at the toad breeding ponds, where scramble competition for mating occurred among the male toads. Thus, we performed two‐choice experiments to investigate recognition ability of mates and species in male toads. The test males did not discriminate sexes, but the clasped stimulus males immediately produced release calls and stopped it while the clasped stimulus female did not. In addition, the test male toads did not discriminate reproductive state of females and even species. However, male toads chose larger individuals. The present results indicate that the main reason of miss‐matched amplexus by the male toads is due to 1) the lack of recognition cues of conspecifics, 2) the lack of communication tools like release calls, and 3) the larger size of bullfrogs than male toads themselves.

Effectiveness of mating call playbacks in anuran call monitoring: A case study of three‐striped pond frogs (Rana nigromaculata)

Abstract We studied the effectiveness of mating call playbacks on call monitoring of three‐striped pond frogs (Rana nigromaculata). Playback experiments were conducted between 2100 to 0030 at 15 sites located at Chungwon, Chungbuk, and Yeongi, Chungnam, in May 2005. We recorded call responses of 25 males to two different call playbacks, (i) single mating calls from a single male and (ii) chorus mating calls from five males, by randomly presenting the calls with a 15 min‐gap between the two playbacks. We compared the number of response calls of the focal males for three min before, during, and after the playbacks. Five of 25 males were silent before stimulus presentation, but all the males emitted calls after the playbacks. The number of calls in response to single playback calls significantly differed among the three playback periods, where males gave more calls during the playback than before or after the playbacks. In addition, subject males presented significantly more calls to single call playbacks than to chorus call playbacks. The results of this study suggest that playback using repeated single mating calls is effective in call monitoring of R. nigromaculata males.