• Journal of Ecology and Environment
• /
• v.30 no.3
• /
• pp.237-244
• /
• 2007

We investigated the foraging habitat preferences of herons and egrets in an agricultural area in Asan city, Chungcheongnam-do, Korea. In the study area, rice fields were the most abundant habitat type (86.8%) and total suitable feeding habitat was greater in the northern area (59.0%) than the southern area (22.5%) of the colony. Most feeding herons and egrets were located in the northern area of the colony. The number of feeding individuals in a given area was related to the available feeding area (Pearson correlation, r=0.773, p<0.001 for field habitats; r=0.901, p<0.001 for freshwater habitats). Feeding habitat preferences differed among species. Grey herons (Ardea cinerea), great egrets (Egretta alba), and black-crowned night herons (Nycticorax nycticorax) used reservoirs and ditches. However, intermediate egrets (E. intermedia) and cattle egrets (Bubulcus ibis) were dependent on rice fields. The little egret (E. garzetta) was a habitat generalist using all types of habitats. The two largest species, grey herons and great egrets, fed at deeper site than little egrets and foraged in deeper sites in reservoirs than in ditches (${\chi}^2-test,\;{\chi}^2{_3}=26.6$ and p<0.001 for grey herons, ${\chi}^2{_3}=17.5$ and p<0.001 for great egrets). All species displayed seasonal changes in feeding habitat use and these changes were related with changes in availability of feeding habitats.

• Journal of Ecology and Environment
• /
• v.31 no.2
• /
• pp.147-151
• /
• 2008

Feeding methods of five species of herons and egrets were studied in an agricultural landscape in Asan city, Chungcheongnam-do, Korea in 2006. Grey herons primarily hunted while standing, whereas great egrets fed while walking slowly. Two smaller species, little and cattle egrets, were active foragers, feeding both while walking quickly and walking slowly. Little egrets were the only species using the foot stirring method. The medium-sized heron, intermediate egrets, foraged mainly while walking slowly or leaning. For grey herons, great egrets and little egrets, the frequency of use of different feeding methods was different between habitats: these species used the leaning method more frequently in rice fields than in reservoirs and ditches. Also, most herons (all species other than great egrets) showed seasonal changes in their feeding methods that are related to changes in habitat condition.

• The Korean Journal of Ecology
• /
• v.19 no.1
• /
• pp.47-53
• /
• 1996

Effects of group breeding of herons on pine community were studied at Pomaeri, in Yangyang, Kangwon Province, Korea. This site has been protected as a Natural Monument (No. 229) since 1970. Herons have used this habitat as a breeding site from] anuary to October every year. In 1995, more than 500 herons were observed in this habitat. Many big pine trees are dying or already dead due to group inhabitation of herons, and no pine saplings were found at forest floor in this habitat. Nutrient contents of soil in this habitat were much higher than those in control plot. This must be due to the addition of feces from herons and of thin twigs and other organic materials from the canopy and bird nests. Species composition of herb layer in this habitat was quite different from that in control plot. Breeding site was dominated by Humulus japonicus. Persiearia perJohata, Persicaria thunbergii. and Commelina communis. which are indicator species of soil eutrophication.

• Journal of Ecology and Environment
• /
• v.34 no.4
• /
• pp.357-363
• /
• 2011

To examine factors affecting feeding efficiency of grey herons (Ardea cinerea), the foraging behavior was studied at a reservoir in Asan city, Chungcheongnam-do, South Korea during the breeding seasons (from April to July) of 2006 and 2007. Four factors (age of foraging birds, time of day, breeding stage, and microhabitat type) were analyzed. Adults were more efficient foragers than recently fledged juveniles, and they had a higher success rate than juveniles. About half of the adults caught large prey, whereas most juveniles caught only small prey. Adult grey herons had different feeding efficiency according to the breeding stage. Pecking and capture rates were high during the late period (fledging stage), and biomass intake rates were high during the early (incubating stage) and late periods. However, time of day had no significant effect on foraging activity of adult grey herons. Feeding activities of adult grey herons also showed significant variation among microhabitat types. Pecking and capture rates were higher in the submerged plants area, but capture success rate and biomass intake rate were not different according to microhabitat type.

• Journal of Korean Society of Forest Science
• /
• v.85 no.3
• /
• pp.506-512
• /
• 1996

Community structure and soil properties of larch forest which are used for breeding site by herons were studied at Apgogri, Hoengsung, Kangwon Province. This site has been protected as a Natural Monument(No. 248) from 1973, in Korea. Herons have used this habitat from February to October every year. In 1995, more than 700 herons were observed in this habitat. Most of the larches died due to group breeding of herons, and no larch saplings were found at forest floor. Nutrient contents of soil in this habitat were much higher than those in control plot(non-breeding site). This must be due to the addition of faeces from herons and of thin twigs and other organic materials from the canopy and bird nests. Species composition of herb layer in this habitat was quite different from that in control plot. Breeding site was dominated by Humulus japonicus, Persicaria fauriei, Persicaria perfoliata, Commelina communis, Chelidonium majus var. asiaticum, Digitaria sanguinalis, Bidens bipinnata. Dioscorea batatas which are indicator species of soil eutrophication. Similarity index of shrub and herb layer between the breeding site and control site was 0.36 and 0.07, respectively.

• Korean Journal of Environment and Ecology
• /
• v.22 no.2
• /
• pp.152-158
• /
• 2008

This survey was conducted to analyze the effect of road construction near the group breeding places of the egrets and herons located at Palhyun-ri, Daegu, on their breeding during four years from 2003 to 2006. With the number of the individuals of the whole egrets and herons have been decreased due to the three-year road construction work(2003-2005). When the road construction was temporally stopped in 2006, the number of individuals of egrets and herons except Cattle egret Bubulcus ibis increased and partocilarly, the Gray heron Ardea cinerea was found to have been influenced the most by this construction in comparison with other egrets and herons. The number od individuals of large egrets, little egrets and herons was found to decrease during the construction period. After cutting off the nest trees and removing some parts of the breeding site, the herons and egrets tended to move their nesting place from roadsides to the inside of the breeding area. Trees for the nests decreased due to the increase in fellen trees caused by bird nests per tree increased gradually. As for the formation ratio of trees for the nests, the ratio of pine trees lowered yearly while that of acacia and oak trees was increasing during the survey.

• Journal of Ecology and Environment
• /
• v.30 no.4
• /
• pp.341-346
• /
• 2007

Nest density was determined and tree and soil characteristics around Nycticorax nycticorax breeding sites and non-breeding sites on Bamsum Island in Seoul were analyzed from May 2005 to October 2006 to identify breeding site preferences of N. nycticorax and the effects of N. nycticorax nesting density on nesting tree structure and soil characteristics. N. nycticorax preferred trees of low height ($3.5{\sim}6$ m) and small diameter at breast height in high density Salix communities. Excrement of heron juveniles was dropped on the soil under the nests. The soil nutrient content under nests (P: 126.0 mg/kg, N: 202.8 mg/kg, EC: 549 ${\mu}S/cm$, pH 4.7) was much higher than that of control soils from Bamsum Island not enriched by heron excrement (P: 41.5 mg/kg, N: 42.0 mg/kg, EC: 342 ${\mu}S/cm$, pH 5.1). Formation of Salix communities on the shores of Bamsum Island is ongoing, and their structure has been directly influenced by annual flooding. After flooding, the nutrient content differences between heron-affected soils and control soils were not significant. This might be the reason that Salix communities on Bamsum were not affected by nesting herons as in other terrestrial communities where herons nest. This result indicates that flooding plays an important role in sustaining Salix communities on Bamsum Island where herons nest. The results of this study may increase understanding of N. nycticorax breeding behavior which may be useful for conservation planning.

• Animal cells and systems
• /
• v.15 no.1
• /
• pp.85-90
• /
• 2011

In 2001, we conducted a study to assess the effects of differential arrival times and nest-site selection on reproductive performance in a mixed-species heronry consisting of six species in Taeseong-ri, Chungbuk, Korea. We recorded the arrival dates, nest heights, clutch sizes, and brood sizes after 15-20 days of the age of the birds' chicks. The grey herons and cattle egrets arrived first and last, respectively, on the colony site. In the homogenous vegetation structure of the breeding site, the pitch pine trees (Pinus rigida) were mainly used for building nests on 48 of the 50 pine trees (96%). The breeding species vertically stratifies the nest sites according to their body size, except for the cattle egrets and black-crowned night herons that nested at sites higher than those predicted from their body size. The mean nest success rates of the six species under study were positively correlated with the mean nest heights. Our findings suggest that aggressive interspecific interactions among neighbors influence nest-site selection to enhance breeding success.

• Journal of Wetlands Research
• /
• v.20 no.3
• /
• pp.256-262
• /
• 2018

Multiple temporal scale can be a useful method to understand population dynamics in ecosystem. The multi-temporal scale approach for population dynamics has rarely been researched till lately. This study was carried out to identify the factors in affecting the population dynamics of herons, including Eastern Cattle Egret (Bubulcus coromadus), Grey Heron (Ardea cinerea), Great Egret (A. alba), Intermediate Egret (Egretta intermedia) and Little Egret (E. garzetta), at rice paddy fields of Seokmun-myeon in the city of Dangjin, South Chungcheong Province during the main breeding periods from 2014 to 2017. We identified the population dynamics of herons at different time interval (day and month) using the unmanned monitoring system. As a result, monthly population dynamics was mostly affected by time, mean temperature and mean precipitation, whereas daily population dynamics was affected by mean temperature and habitat types. The results suggest that there are differences in the factors affecting the population dynamics of herons according to the time scale.

• Korean Journal of Environment and Ecology
• /
• v.23 no.6
• /
• pp.564-568
• /
• 2009

The principal objective of this study was to determine and characterize the food resources and foraging sites of Pacific Reef Herons bred in Aewol-eup, Jeju Island, during Feb. 2005 ~ Aug. 2005. The food resources of Pacific Reef Herons were identified as comprising 21 individuals of 5 species, and these identifications were verified as follows: 38.1% of Tridentoger obscurus(n=8), 19.0% of Ennedpterygius etheostomus(n=4), and 14.3% of Engraulis japonica(n=3). The sizes of the food resources were measured as follows: total $58.29{\pm}5.17mm$(n=19), T. obscurus was $67.49{\pm}4.91mm$(n=8), E. etheostomus was $43.98{\pm}3.50mm$(n=4), and E. japonica was $22.77{\pm}1.17mm$. The semi-digested foods were confirmed as Paralichthys olivaceus and Sebastes inermis. The primary foraging sites were 7.4km(Oedocheon) east, to 6.6km(Geumseongcheon) west of the Aewol breeding area.