• Korean Journal of Environment and Ecology
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• v.38 no.2
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• pp.143-147
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• 2024

This study aimed to determine the egg-hatching period of boreal digging frogs, Kaloula borealis, and investigate whether the incubation temperature affects the hatching period. In this study, the egg hatching was recorded based on the appearance of the tadpole. The results of this study showed that all the eggs hatched within 48 hours after spawning, with 28.1% (±10.8, n=52) hatching within 24 hours and 99.9% (±0.23, n=49) within 48 hours after spawning. The mean hatching rate of tadpoles showed significant differences depending on the difference in water temperature. The mean hatching rate between 15 and 24 hours after spawning was higher at a water temperature of 21.1 (±0.2) ℃ than at 24.1 (±0.2) ℃. The results suggest rapid hatching occurs at relatively low water temperatures because the spawning habits that spawn eggs in temporary ponds or puddles in the rainy season require rapid hatching before the puddles dry out. The results of this study are helpful for understanding the most suitable temperature conditions for the incubation of eggs of the endangered species, boreal digging frog.

• Journal of Ecology and Environment
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• v.38 no.4
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• pp.415-424
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• 2015

This research was conducted to reveal the characteristics of breeding ecology of oriental scops owl (Otus sunia stictonotus) inhabiting in South Korea according to the nest types during the breeding season from march to October for two years (2011 and 2012). Oriental scops owl nested in woodpecker's nest holes (46.1%), natural tree holes (38.5%), and artificial wood boxes (15.4%). These nests were located on following trees: Zelkova serrata, Paulownia coreana, Celtis sinensis, Salix chaenomeloides, Salix babylonica, Fraxinus rhynchophylla, Robinia pseudoacacia and Platanus occidentalis. The hatching success was 91.4%, fledging success was 83.0%, and breeding success was 75.9%. The factors of the breeding failure were falling (57.1%), abandonment (28.6%), hatching failure (7.1%), and others with unknown cause of death (7.1%). According to nest types, the fledging success (69.2%) of woodpecker's nest holes were low and the hatching success (79.2%) of natural tree holes were also low due to hatching failure and abandonment. However, hatching success, fledging success, breeding success were high in the artificial nests as all the eggs hatched and succeeded in fledging. Therefore, we suggested that artificial nests can cover the weaknesses of natural nests as well as increasing the breeding success. However, long-term research on installation place, height, and hole sizes of the artificial nest are required in order to clearly reveal the effects on the breeding success of oriental scops owl.

• Korean Journal of Environment and Ecology
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• v.22 no.1
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• pp.59-65
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• 2008

This study is mainly focused on the mating of 9 couples of Eagle Owl Bubo bubo habitating in Paju, Ganghwa Island, Icheon, Sihwa Lake, Chungju. For this study, from 2005 to 2007, regular filming and mornitoring for the breeding ecology and copulation behavior of 9 couples of Eagle Owl in the nest and near area had been done. Clutches ranged in size from one to four eggs but averaged 2.27 eggs(n=15), hatching success rate was 71 %(n=34) and fledgling success rate was 83%(n=23). Through the filming and mornitoring, it was found that Eagle Owl continued to copulate each other even after hatching and kept its copulation until the chicks left their nest($7\sim8$ weeks after hatching). This copulation behaviour without fertilization seems to be done for confirming, maintaining and strengthening of pair-bond by the necessity of both male and female, and to aim at stable breeding of their chicks.

• Korean Journal of Environment and Ecology
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• v.37 no.3
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• pp.192-197
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• 2023

This study was conducted to determine whether the difference in egg hatching temperature of Korea Reeves' turtle (Mauremys reevesii) at the artificial nursery of Seoul National Grand Park affects the incubation period and growth. A total of 201 eggs were incubated at 26 ℃ (n=89), 28 ℃ (n=75) and 32 ℃ (n=37). The incubation period of eggs showed significant differences according to the hatching temperature. In this study, the higher the hatching temperature, the higher the hatching rate. The incubation period of the eggs hatched at 26 ℃, 28 ℃ and 32 ℃ was 66.1 (±4.0, n = 52) days, 65.3 (±3.3, n = 44) days and 58.8 (±7.7, n = 31) days, respectively. Eggs incubated at 32 ℃ (83.8%) had a higher hatching success than those at 26 ℃ (58.4%) and 28 ℃ (58.7%). The body mass of 14-day-old hatchlings incubated at 32 ℃ was greater than those incubated at 26 ℃ and 28 ℃. However, there was no significant difference in the mean body mass of 180 and 270-day-old turtles hatched at these different temperatures. This study showed that the hatching temperature significantly affected the incubation period and body mass in the early life of the Korea Reeves' turtle (M. reevesii).

• The Korean Journal of Ecology
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• v.25 no.4
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• pp.241-245
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• 2002

During the breeding season of 1998, breeding ecology of the Great Reed-Warbler (Acrocephalus arundinaceus orientalis) was studied at Yangsoo-ri and Yongdam-ri of the Yangpyung-gun, Kyunggi province, Korea. Egg-weight (CV: 6.25) was more variable than either length or breadth, and breadth was the least variable of the measures. Significant variations in overall egg-weight occurred between clutches, and that more of the total variation in egg-weight and shape are due to inter-clutch variation as to intra-clutch variation when the data were pooled. The last egg tends to be larger than the remaining eggs in the clutch of the Great Reed-Warbler, suggesting the Great Reed-Warbler may adopt the brood-survival strategy. When method 3 was used, the most common incubation period is 12 days. In the Great Reed-Warbler, the length of the incubation period was related to clutch-size when method 1 (r=0.485, p<0.05) and method 2 (r=0.621, p<0.01) were employed, but not related to egg weight. The averagee number of days of hatching asynchrony was 2.5, raging 0.5~2.5. Asynchronous hatching was related to the clutch size (r=0.66, p<0.01). Hatching sequence was closely related to the laying sequence (r=0.93, p<0.001), suggesting Great Reed-Warblers incubate their eggs before clutch completion. The effect of egg weight on hatching asynchrony was found in Great Reed-Warblers (t-test, p<0.01).

• Journal of Ecology and Environment
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• v.31 no.3
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• pp.201-206
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• 2008

This study was conducted to determine clutch size and habitat usage of Kentish plovers (Charadrius alexandrinus) breeding on Sinja-do lslet in the Nakdong Estuary from 22 April to 12 July in 1995 and from 21 April to 20 June in 1996. The Kentish plover preferred grasslands and damp sands to dry dunes as nesting sites. The difference in hatching success among these microhabitats was attributed to high tides, which washed away many nests on damp sands, and strong winds, which frequently shifted the sand to bury eggs on dry dunes. The main mortality factor in grasslands was predation by magpies Pica pica. Each clutch contained one to four eggs, with a mode of three eggs. Hatching success was highest in two-egg clutches and lowest in one- and four-egg clutches. The mean interval for egg laying was 1.8 days between the first and second eggs and 2.1 days between the second and third eggs. The average incubation period was about 24.2 days.

• The Korean Journal of Ecology
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• v.25 no.6
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• pp.365-369
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• 2002

We had 18 eggs artificially hatched in a mass breeding place of black-tailed gulls and examined the individual recognition between young siblings in a laboratory environment. The results of the experiment showed that the young gulls selectively responded to their siblings and non-siblings at an early stage after hatching. It was shown that they began to recognize the begging call among the voice signals of siblings and non-siblings 15-16 days after hatching, and the chirirah call 11-12 days after hatching. Also, more significant results were shown with the chirirah call than with the begging call. In an experiment of visual recognition between siblings and non-siblings, the young black-tailed gulls approached their siblings significantly 9-10 days after hatching. The recognition between young siblings in a mass breeding place provides an important evolutionary indicator in terms of their social behaviors.

• 한국생태학회:학술대회논문집
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• 2002.08a
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• pp.107-111
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• 2002

During the breeding season of 1998, breeding ecology of the Great Reed-Warbler (Acrocephalus arundinaceus orientalis) was studied at Yangsoo-ri and Yongdam-ri of the Yangpyung-gun, Kyunggi province, Korea. Egg-weight (CV: 6.25) was more variable than either length or breadth, and breadth was the least variable of the measures. Significant variations In overall egg-weight occurred between clutches, and that more of the total variation in egg-weight and shape are due to inter-clutch variation as to intra-clutch variation when the data were pooled. The last egg tends to be larger than the remaining eggs in the clutch of the Great Reed-Warbler, suggest- ing the Great Reed-Warbler may adopt the brood-survival strategy. When method 3 was used, the most common incubation period is 12 days. In the Great Reed-Warbler, the length of the incubation period was related to clutch-size when method 1 (r=0.485, p<0.05) and method 2 (r=0.621, p<0.01) were employed, but not related to egg weight. The average number of days of hatching asynchrony was 2.5, raging 0.5∼2.5. Asynchronous hatching was related to the clutch size (r=0.66, p<0.01). Hatching sequence was closely related to the laying sequence (r=0.93, p<0.001), suggesting Great Reed-Warblers incubate their eggs before clutch completion. The effect of egg weight on hatching asynchrony was found in Great Reed-Warblers (t-test, p<0.01).

• Journal of Ecology and Environment
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• v.29 no.1
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• pp.35-39
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• 2006

During the breeding seasons in 2002 and 2003, the influences of vegetation cover on breeding processes of Black-tailed Gulls (Laurs crassirostris) were studied on Hongdo Island. We checked dutch sizes, calculated hatching success and survival rates on day 15 and a vegetation cover, There was significant positive relationship between vegetation cover and hatching success, and survival on day 15. In order to analyze the relationship, sample nests were categorized as 'exposed' and 'covered' nests, and the breeding processes at each nest were compared. Hatching success and survival on day 15 in covered nests were significantly higher than ones in exposed nests. However, in clutch size, there was no significant difference. The rate of the hatching and survival failure was different amongst the categorized nests. The primary cause of hatching failure in covered and exposed nests was 'disappeared', and the primary causes of survival failure on day 15 were 'disappeared' and 'killed by adults'. The failure in exposed nests was significantly larger than that of covered nests. In the breeding of Black-tailed Gulls on Hongdo Island, vegetation cover influenced the survival of eggs and chicks as the cover provided shelter against predators and extreme weather.

• Korean journal of applied entomology
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• v.48 no.2
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• pp.221-227
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• 2009

Temperature effects on diapause termination of Paratlanticus ussuriensis eggs were studied by measuring embryonic development and hatching rates at various conditions of indoor chilling and overwintering temperatures. Diapausing eggs of P. ussuriensis did not hatch at continued incubation at $25^{\circ}C$ and even after chilling for once at either $5^{\circ}C$ or $10^{\circ}C$ for 30, 45 and 60 days. In addition, double chillings at $5^{\circ}C$ with a 90 days interval at $25^{\circ}C$ did not induce hatching of diapausing eggs. However, double chillings at $10^{\circ}C$ induced hatching at 3.6${\sim}$26.7%. When eggs were incubated at $25^{\circ}C$ after chilling for once at $5^{\circ}C$ for various periods, those weights were not changed but those chilled at $10^{\circ}C$ gradually increased to approximately 1.5 times. When 60-days-old eggs were artificially deposited under the soil at three different mountain sites in September 2007, the hatching rates of the first-overwintered eggs were 11.3, 3.5 and 4.1% and those of the second-overwintered eggs were 25.1, 21.6 and 0.4% at Hoepori, Bitanri and Hwasanri, respectively. Most eggs were hatched from mid-March to mid-April but little bit earlier in southern regions. During the hatching period soil temperatures in three tested locations were around 8 to $12^{\circ}C$. In overall, diapausing eggs of P. ussuriensis were greatly influenced by chilling temperature conditions and those repeated cycles, and may required overwintering for one or two times to hatch for the post-embryonic development.