• Journal of Ecology and Environment
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• v.31 no.1
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• pp.69-73
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• 2008

We studied the functional roles of two types of calls, mew calls and mobbing calls, of the black-tailed gull (Larus crassirostris) by examining responses of mixed flocks of gulls to the playback calls. Playback experiments were conducted on four days between 11 May and 5 June 2007 at 16 sites in Sinjindo-ri and Dowhang-ri, Taean-gun, Chungnam province and Imjado, Sinan-gun, Jeonnam province, South Korea. We examined the anti-predator responses of the gulls to the playback trials. We found that gull flocks initially responded to mew call playbacks by mobbing in less than half of playback trials (6/14) while all trials involving playbacks of the mobbing call and control (group mobbing) call evoked mobbing. When trials in which no response was recorded were excluded, we found that the gulls' responses to mobbing and group mobbing call playbacks was more intense than their response to mew call playbacks, in that gulls mobbed longer, more gulls responded, and gulls took flight after a shorter time interval. However, the intensity of the gulls' response did not differ in mobbing call and group mobbing call playbacks. The results of this study suggest that the mixed-species flocks of gulls discriminate between the mew calls and the mobbing calls.

• Journal of Ecology and Environment
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• v.36 no.4
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• pp.217-222
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• 2013

Sea temperature in the South Sea of Korea has been increased over the last decades. Seabirds are sensitive to changes in food availability in marine environment. In this study, we investigate the diet of Black-tailed gulls (Larus crassirostris) during the breeding season to identify changes of marine environment and biological response such as breeding performance in the South Sea of Korea. A total of 22 fish species or family (n = 128) from regurgitates by chicks were collected on Hongdo Island in 2002 and 2012. The most important prey item was Japanese anchovies (Engraulis japonicas). Proportion of Anchovy in diet increased in 2012 (70.5%) compared to 10 years ago (27.5%). Some species were newly found in 2012: Spotted chub mackerel (Scomber australasicus), Pacific sand lace (Ammodytes personatus), White ventral goby (Acanthogobius lactipes), Silver-strip round herring, Multicolorfin rainbowfish (Halichoeres poecilopterus), Silverside (Hypoatherina tsurugae), Surfperch (Neoditrema ransonneti) and Spotnape ponyfish (Leiognathus muchalis), but not in 2002. Especially, sub-tropic fish such as Kammal thryssa (Thryssa kammalensis), and Rosefish (Helicolenus hilgendorfi) were frequently observed in the diet of 2012. These results might reflect the increase of sea temperature in the South Sea of Korea.

• Ocean and Polar Research
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• v.28 no.2
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• pp.201-207
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• 2006

We studied variation in clutch size, hatching, fledging and breeding success of the Black-tailed Gull (larus crassirostris) at Hongdo Island, which supported the largest breeding colony of the species, in South Korea in 1997 and 2000 to 2003. Cluck size was recorded in 1,388 nests and breeding success was estimated in 83 nests. Mean clutch size was 1.89 t 0.65. A total of 63.9% of the eggs hatched and 53.5% of the chicks survived until fledged. Breeding success was 34.2%. Causes of breeding failure were eggs missing (14.9%), rotten eggs (15.5%) and predation (2.4%) during the incubation period and chicks missing(35.8%), starvation (7.4%) and pecked chicks (3.2%) during the chick rearing period. In 2002, the main causes of breeding failure were eggs missing (17.2%) and rotten eggs (6.9%) during the incubation period and missing chicks (15.5%), starvation (3.5%) and pecked chicks (6.9%) during the chick rearing period. Most chick mortality occurred within three days after hatching.

• Animal cells and systems
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• v.6 no.3
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• pp.221-225
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• 2002

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 1.8s. The adult long ca11 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.

• Proceedings of the Zoological Society Korea Conference
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• 1998.10b
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• pp.157.1-157
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• 1998

No Abstract, See Full Text

• Journal of Ecology and Environment
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• v.30 no.1
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• pp.9-15
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• 2007

Black-tailed gulls (Larus crassirostris) produce alarm calls apparently related to their anti-predator behaviors, but the hypothesis that the calls are actually used as functionally referential alarm signals has not yet been tested. In this study, we performed a series of experiments using visual (a stuffed goshawk: Accipiter gentilis) and acoustic (alarm calls and a control vocalization) stimuli at 15 sites in Sinjindo-ri and Dowhang-ri, Taean-gun, Chungnam province to examine anti-predator responses of the gulls to alarm calls in playback trials. We found that the gulls' visual recognition of a perched hawk model in the absence of alarm vocalizations was weak or absent because the model was noticed in only two out of 16 trials. The gulls' responses to playbacks of the alarm call only and the alarm call with a visual stimulus differed from responses to the control vocalization in latency to approach, time mobbing, and the percentage of gulls responding, while the responses to alarm call only differed from alarm call with a visual stimulus in latency to first fly, latency to call, and time mobbing. The results of this study suggest that alarm calls of black-tailed gulls are used to elicit appropriate anti-predator behaviors that are intensified when a predator is detected visually.

• Journal of Environmental Impact Assessment
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• v.22 no.6
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• pp.745-751
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• 2013

Environmental Specimen Banks (ESBs) have been established widely in the world since 1979 for monitoring long-term bio-accumulation of environmental pollutants. The ESBs perform the retrospective analysis of representative biological samples collected regularly and store them in cryogenic condition. In Korea, National Environmental Specimen Bank (NESB) was established in 2009. Since then, NESB had prepared the standard operating procedures (SOPs) for the seven kinds of specimens (Red Pine (Pinus densiflora), Common Carp (Cyprinus carpio), and etc.) for monitoring the effect of environmental pollution on the terrestrial ecosystem and river ecosystem. In 2012, NESB added Black-tailed Gull (Larus crassirostris)'s eggs to the list of the environmental specimen for monitoring marine environmental pollution. In this study, we sampled the eggs of the Black-tailed Gull on two islands (Baekryeongdo of the West Sea and Hongdo of the South Sea). Especially, we selected eggs which remained in the early stages of embryo development for certifying the consistent and stable monitoring for environmental pollutants in egg contents. However, it was not considered to classify an order of eggs per clutch in this study. It is known that the concentration variations of pollutants exist among eggs in one clutch. Therefore, it is needed to consider the positions of eggs in the laying sequences to meet the objective of bioaccumulation monitoring. We collected 30 eggs in each site but the amount may be insufficient to achieve storage target (over 2,000 g). Therefore, we need to consider an optimal sampling size.

• Proceedings of the Zoological Society Korea Conference
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• 1998.10b
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• pp.155.2-155
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• 1998

No Abstract, See Full Text

• Proceedings of the Zoological Society Korea Conference
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• 1998.04a
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• pp.39.1-39
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• 1998

No Abstract, See Full Text

• Proceedings of the Zoological Society Korea Conference
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• 2003.08a
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• pp.134.3-134
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• 2003

No Abstract, See Full Text