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Dive into the research topics where Hyun-Young Nam is active.

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Featured researches published by Hyun-Young Nam.


Vector-borne and Zoonotic Diseases | 2013

Molecular Detection of Anaplasma, Bartonella, and Borrelia Species in Ticks Collected from Migratory Birds from Hong-do Island, Republic of Korea

Jun-Gu Kang; Heung-Chul Kim; Chang-Yong Choi; Hyun-Young Nam; Hee-Young Chae; Sung-Tae Chong; Terry A. Klein; Sungjin Ko; Joon-Seok Chae

Bird migration is a recurring annual and seasonal event undertaken by more than 100 species of birds in the southeast Asian and northeast Palearctic regions that pass through or remain for short periods from April to May and September to November at Hong-do Island, Republic of Korea (ROK). A total of 212 ticks (40 Haemaphysalis flava, 12 H. longicornis, 146 Ixodes turdus, 13 I. nipponensis, and 1 I. ornithophila) were collected from 65/2,161 (3.0%) migratory birds consisting of 21 species that were captured from January, 2008, through December, 2009, as part of the Migratory Birds Center, Hong-do bird banding program for studying bird migration patterns. Adult ticks were assayed individually while larvae and nymphs were pooled (1-22 and 1-6 ticks per pool, respectively) into 31 and 65 pools, respectively. Ticks were assayed for zoonotic pathogens by PCR using 16S rRNA, heat shock protein (groEL), and internal transcribed spacer (ITS) gene primers to amplify genera specific for Anapalsma, Bartonella, and Borrelia PCR amplicons. Using the 16S rRNA-based nested PCR, A. phagocytophilum (n=1) was detected in I. nipponensis collected from Zoothera sibirica and A. bovis (n=1) was detected in I. turdus collected from Emberiza chrysophrys. Borrelia turdi 16S rRNA genes (n=3) were detected in I. turdus and I. nipponensis collected from Turdus pallidus and Zoothera aurea. Borrelia spp. 16S rRNA genes (n=4) were detected in Ixodes ticks collected from Emberiza tristrami, T. pallidus, and Z. aurea. The Bartonella grahamii ITS gene (n=1) was detected by nested PCR assay in I. turdus collected from Z. aurea. These results provide insight into the potential role of migratory birds in the dispersal of ticks and associated tick-borne pathogens throughout their ranges in Asia.


Journal of Ecology and Environment | 2010

Exotic Seeds on the Feathers of Migratory Birds on a Stopover Island in Korea

Chang-Yong Choi; Hyun-Young Nam; Hee-Young Chae

Migratory birds, by crossing significant ecological barriers, carry and may subsequently introduce exotic seeds into new ecological zones during period of migration. The study of epizoochory, which includes seed dispersal by adhesion to bird feathers, has been relatively neglected compared to the study of seed dispersal by frugivores. To determine whether exotic seeds are being imported to stopover islands by migrating birds, and to estimate the quantity of seeds of exotic species being introduced, we examined migratory birds that were captured in mist nets for attached exotic plant diaspores in 2008 and 2009 on Hongdo Island, Korea. From a total of 3,947 birds examined, we found exotic seeds of Japanese Chaff Flowers (Achyranthes japonica) attached to three species of migratory birds (0.08%; Eurasian Bittern Botaurus stellaris, Swinhoes Rail Coturnicops exquisitus and Oriental Turtle Dove Streptopelia orientalis). Despite the low occurrence of A. japonica seeds on the external parts of birds, the results suggest that migratory birds may be potential dispersing agents for A. japonica, a species that is currently threatening native ecosystems on many islands in Korea.


Waterbirds | 2007

Measuring the Behaviors of Wintering Black-faced Spoonbills (Platalea minor ): Comparison of Behavioral Sampling Techniques

Chang-Yong Choi; Hyun-Young Nam; Woo-Shin Lee

Abstract We recorded the diurnal behaviors of the endangered Black-faced Spoonbill (Platalea minor) for 16 days during the wintering season in Jeju Province, Korea to find an appropriate and effective sampling technique for behavioral study. Two main techniques were used and compared: focal sampling with continuous recording and scan sampling with instantaneous recording at various time intervals. As a result, recording the behavior of a focal bird for more than 20 min per h was the best technique with high accuracy and precision. However, to select less time- and labor-intensive techniques we concluded that scan samplings with less than 10 min intervals or focal samplings with more than 15 min durations are appropriate measurements of the spoonbill’s behaviors. Considering sampling sizes, scan sampling with 5 min recording intervals can be an effective technique but additional methods are also required to obtain significant information for infrequent or occasional behaviors. We suggest that each sampling technique should be validated by preliminary or supplementary surveys to estimate the endangered animal’s behaviors and this can be an important part of the groundwork for conservational efforts on the Black-faced Spoonbill.


Synthetic Metals | 1993

The I–V characteristics of the gas phase doped copper phthalocyanine/Si heterojunctions

Chung-Gyu Park; Hyun-Young Nam; A.A. Ovchinnikov; Y.W. Park

Abstract The heterojunction properties of Copper Phthalocyanine(CuPc) evaporated on n-type or p-type silicon are investigated using I–V measurements. The CuPc was doped with oxygen, NO χ , or iodine, respectively, via the gaseous phase doping. For the anisotope heterojunction of CuPc/n-Si, the ideality factor is about 2 for all dopants and the current increases upon doping. But for the isotope heterojunctions of CuPc/p-Si, the junction properties are very sensitive to each dopant.


Systematic & Applied Acarology | 2009

Migratory bird tick surveillance, including a new record of Haemaphysalis ornithophila Hoogstraal and Kohls 1959 (Acari: Ixodidae) from Hong-do (Hong Island), Republic of Korea

Heung Chul Kim; Sungjin Ko; Chang-Yong Choi; Hyun-Young Nam; Hee-Young Chae; Sung Tae Chong; Terry A. Klein; William J. Sames; Richard G. Robbins; Joon-Seok Chae

Abstract In 2008, tick surveillance of migratory birds was conducted on Hong-do (Hong Island), Jeollanam Province, Republic of Korea. Seventy-seven ticks representing two genera and four species—Haemaphysalis flava Neumann (21 ticks), Haemaphysalis ornithophila Hoogstraal & Kohls (2), Ixodes nipponensis Kitaoka & Saito (3), and Ixodes turdus Nakatsuji (51)—were collected from 12 species of birds belonging to nine genera. Two male H. ornithophila, an uncommonly collected tick, were removed from a scaly thrush, Zoothera dauma (Latham), on Hong-do. Haemaphysalis ornithophila is a Southeast Asian species that was transported to Korea during the spring migration of Z. dauma to its breeding grounds in Russia. This first report of H. ornithophila from Korea has implications for the introduction of exotic tick species and their pathogens on migratory birds.


Journal of Ecology and Environment | 2006

Edge Preference of Forest-dwelling Birds in Temperate Deciduous Forests

Chang-Yong Choi; Hyun-Young Nam; Wee-Haeng Hur; Woo-Shin Lee; Hyun-Joong Kim; Geun-Yeoun Hwang

본 연구는 중부 온대활엽수림을 대표하는 광릉 숲을 대상으로 산림성 조류가 숲의 내부와 가장자리를 어떻게 이용하는지 파악하고, 숲의 단편화로 인한 영향을 파악할 수 있도록 서식지 특이종을 선정하기 위해 실시되었다. 그 결과 조류의 풍부도는 숲의 내부와 가장자리에서 일관성 있는 결과를 얻지 못하였으며, 이는 숲 내부와 가장자리를 모두 이용할 수 있는 일반종의 출현 여부에 의해 크게 좌우되었다. 따라서 산림의 단편화가 산림성 조류에 미치는 영향을 파악하기 위해서는 전체 조류군집의 풍부도를 확인하는 것보다 특정 환경을 선호하는 서식지 특이종의 변화를 집중적으로 파악하는 것이 유리할 것으로 판단되었다. 선 조사법과 정점 조사법에 의해 얻어진 숲 내부와 가장자리의 서식밀도를 기준으로 서식지 특이종을 파악한 결과 숲새(U. squameiceps), 흰배지빠귀(T. pallidus), 진박새(P. ater) 등 3종이 숲 내부종으로 나타났으며 까치(P. pica), 꾀꼬리(O. chinensis)의 2종은 숲 가장자리종으로 나타났다. 따라서 광릉 숲으로 대표되는 중부 온대활엽수림의 단편화에 의한 산림성 조류의 영향을 파악하기 위해서는 서식지 특이종으로 파악된 종을 대상으로 한 분포와 번식 등에 대한 모니터링이 필요하며, 특히 숲의 내부에 강한 선호도를 보이는 종에 대한 조사가 우선되어야 할 것으로 판단된다.


Journal of Ecology and Environment | 2007

Nest Box Preference by Secondary Cavity-Nesting Birds in Forested Environments

Chang-Yong Choi; Hyun-Young Nam; Eun-Jae Lee; Ok-Sik Chung; Yong-Su Park; Jong Koo Lee; Jee-Yun Hyun; Woo-Shin Lee

We placed and monitored 2,137 nest boxes to determine how the size of the entrance hole and the box placement influenced nest box selection by secondary cavity-nesting birds and to derive recommendations for the use of nest boxes for management of cavity-nesting birds in forested environments. A total of 566 pairs of seven bird species used the nest boxes from 1997 to 2006, 562 of which were secondary cavity-nesters. Sympatric tits such as varied tits (Parus varius), great tits (P. major), and marsh tits (P. palustris) were common breeding birds in nest boxes, and showed clear preferences for 4.0 cm, 3.5 cm and 3.0 cm nest holes, respectively. Tree sparrows (Passer montanus) and Eurasian nuthatches (Sitta europaea) preferred 4 cm and 3.5 cm holes, respectively. We did not detect selection for the directional orientation for the entrance hole, but the birds appeared to avoid nest boxes that faced steep or gentle upward slopes and those less than 1.8 m from the ground. These results are probably related to avoidance of disturbance and predation. We suggest that diverse species can be supported by the placement of nest boxes with entrance holes of various sizes and that specific species can be targeted by selecting the hole sizes preferred by those species. To attract secondary cavity-nesters, managers should avoid placing nest boxes close to the ground and facing hills. This study also suggests that careful selection and placement of nest boxes is needed to avoid biases in research using nest boxes.


Journal of Raptor Research | 2015

Diet of Peregrine Falcons (Falco peregrinus) in Korea: Food Items and Seasonal Changes

Chang-Yong Choi; Hyun-Young Nam

Abstract Although the diet of Peregrine Falcons (Falco peregrinus) has been studied worldwide, little information on the species’ feeding behavior has been reported for East Asia. To document prey composition and seasonal foraging habits, we collected prey remains and observed hunting behavior of Peregrine Falcons from 2001 to 2013 in the Republic of Korea. We identified 362 prey items comprising 77 species, including two insect species, two globally threatened avian species, and three owls. We found wide variation in prey mass, ranging from 0.3 g to 1103 g; the geometric mean prey weight (GMPW) was 128.8 ± 3.5 g, and 74.3% of prey taxa were <240 g in body mass. The diversity and body mass of peregrine prey varied seasonally; peregrines tended to hunt for a few large-bodied prey species in winter when nonbreeding waterbirds were most abundant, whereas they fed on small- to medium-sized birds during other seasons. In particular, peregrines fed on more species in spring and autumn, likely because of the increased diversity and abundance of migratory birds in those seasons. Our results indicated that Peregrine Falcons in Korea show opportunistic food habits, with diet varying according to seasonal prey availability.


Wildlife Research | 2014

Behavioural responses of wintering black-faced spoonbills (Platalea minor) to disturbance

Chang-Yong Choi; Hyun-Young Nam; Woo-Shin Lee

Abstract Context. Behavioural responses can be used to understand the impacts of disturbance on animals and to develop management strategies, and there is considerable conservation interest in quantifying the effects of disturbances on wild animals. Aims. We seek to formulate a management plan for the endangered black-faced spoonbills (Platalea minor) in a non-breeding ground, on the basis of their behavioural responses to different types of stimulus categorised by threat level (threatening vs non-threatening) and human involvement (anthropogenic vs natural). Methods. We documented 16 stimuli from 379 disturbance events through continuous observation on 31 daily selected focal individuals, and estimated flight distances caused by human approach under different conditions at a non-breeding site in Korea. Key results. The spoonbills showed the strongest behavioural response to the non-threatening anthropogenic stimuli, and human approach followed by motor vehicles caused longer responses per event than did any other type of disturbing stimulus. Flight distance caused by human approach varied depending on conditions; inactive spoonbills in mixed-species associations started to flee at the greatest distance (197.4 m, with a 50% probability), whereas the spoonbills in a single conspecific flock were the most tolerant of human approaches, regardless of their activeness (61.0–61.7 m, with a 50% probability). Conclusions. Human approach had been identified as the most important disturbing stimulus that should be controlled as a priority. We also suggest that black-faced spoonbills benefit from the presence of other waterbirds and exploit them as an early warning system. Implications. The tolerance of sympatric species as well as the behavioural response of target species should be considered when a buffer area for wildlife management, particularly against human disturbance, is planned. How the site has been used and what the species composition is are still important components for the design of safe refuges and roosts.


Journal of Raptor Research | 2013

Morphometrics and Sexual Dimorphism of Chinese Goshawks (Accipiter soloensis)

Chang-Yong Choi; Hyun-Young Nam; Jong-Gil Park; Gi-Chang Bing; Chang-uk Park; Sook-Young Cho

Abstract Sex determination is a key component in many ecological and evolutionary studies, and morphological measurements, based on reversed sexual size dimorphism (RSD), are the most widely used means of sexing raptors. We studied morphometrics and sexual dimorphism of the poorly documented Chinese Goshawk (Accipiter soloensis) in the Republic of Korea, where we measured 54 birds and developed discriminant functions to allow sexing. The species showed apparent, but small, RSD in all of eight measured parameters, with the dimorphic index ranging from 1.39 for tarsus to 16.09 for body mass. A stepwise discriminant procedure, followed by discriminant function analysis (DFA), indicated that tail, bill, and head lengths were all reliable parameters for sex determination of goshawks with an accuracy of 100% among 30 individuals. Head length is often unavailable from museum specimens; however, a discriminant function using tail and bill lengths classified the sex of 44 goshawks with an accuracy of 95.5%. Our morphometric data and discriminant function may benefit further studies on the Chinese Goshawk by allowing easy sexing of most birds. MEDIDAS MORFOMÉTRICAS Y DIMORFISMO SEXUAL DE INDIVIDUOS DE ACCIPITER SOLOENSIS La determinación del sexo es un componente clave en diversos estudios ecológicos y evolucionarios, y las medidas morfométricas, basadas en el dimorfismo sexual invertido (DSI) son los medios más utilizados para determinar el sexo de las rapaces. Estudiamos las medidas morfométricas y el dimorfismo sexual de la especie rapaz poco documentada Accipiter soloensis en la República de Corea, donde medimos 54 aves y desarrollamos funciones discriminantes para permitir la determinación del sexo. La especie evidenció un DSI aparente pero pequeño en los ocho parámetros medidos, con el índice de dimorfismo variando de 1.39 para el tarso a 16.09 para la masa corporal. Un proceso discriminante paso a paso, seguido de un análisis de función discriminante (AFD), indicaron que las longitudes de la cola, el pico y la cabeza son todos parámetros confiables para la determinación del sexo de individuos de A. soloensis con una precisión del 100% en 30 individuos. El largo de la cabeza a menudo no se encuentra disponible en especímenes de museo; sin embargo, una función discriminante usando las longitudes de la cola y del pico clasificó el sexo de 44 individuos de A. soloensis con una precisión del 95.5%. Nuestros datos morfométricos y la función discriminante pueden beneficiar a otros estudios de A. soloensis al permitir una fácil determinación del sexo de la mayoría de las aves.

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Chang-Yong Choi

Seoul National University

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Woo-Shin Lee

Seoul National University

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Eun-Jae Lee

Seoul National University

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Joon-Seok Chae

Seoul National University

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S.R. Lee

Ewha Womans University

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Sungjin Ko

Seoul National University

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