Seung-Hun Son

Effects of Mixing on the Aggressive Behavior of Commercially Housed Pigs.

In this study, we investigated the effects of mixing on the aggressive behavior of commercially housed pigs. The behavioral patterns of 36 groups of pigs (a total of 360 animals) were observed over 3 consecutive days directly after weaning (25±1.2 days of age), and 25 and 50 days later with the aid of video technology. Fight latency and total duration and frequency of fighting were significantly different among the age groups. The aggressive behaviors decreased in 75-day old pigs if compared to 25- and 50-day old animals. Moreover, dominance index (DI) was higher in 25-day old and lower in 75-day old pigs. A comparison of dominant (DI>0) and submissive (DI<0) pigs showed significant differences (p<0.05) for major aggressive behaviors in all age groups. Dominant pigs were involved in more aggressive interactions, had longer fights, and initiated more fights than submissive pigs. Post-mixing aggressive behavior was altered by previous experience of mixing. Aggressive behavior and DI are suitable methods for analyzing the effects of mixing on commercially housed growing pigs.

Differences in Small-Mammal and Stand Structures between Unburned and Burned Pine Stands Subjected to Two Different Post-Fire Silvicultural Management Practices

We examined the abundances of three small-mammal species, Korean field mice (Apodemus peninsulae), Korean red-backed voles (Myodes regulus), and striped field mice (A. agrarius), and a stand structure of unburned and burned stands resulting from two different post-fire silvicultural management practices within a pine forest in South Korea. The habitat structure changed dramatically depending on the post-fire silvicultural practices. Most measured variables of the stand structure and downed trees were significantly different among the differently-managed stands. We captured 776 animals of five species (1114 captures in total) in nine stands, each trapped during the two-year study period. The total abundances of captured small mammals did not differ significantly among the differently-managed stands. Mean Jolly—Seber estimates of the population density of M. regulus were 79%–291% higher in the post-burned untreated stand, whereas those of A. agrarius were 214%–491% higher in the post-burned Japanese red pine (Pinus densiflora) planted stand. The preferred stands for small mammal species were generated by forest fire and post-fire silvicultural practices. The values of understory vegetation, coarse woody debris, and downed trees were most strongly related to small-mammal abundance following post-fire silvicultural practices. Therefore, the effects of post-fire silvicultural practices on small-mammal populations should be considered in the post-fire management of a burned pine forest.

Behavioral Characteristics of Weaned Piglets Mixed in Different Groups.

With regard to animal welfare concerns, behavioral information of weaned and mixed piglets is great interest in swine production. The aim of this study was to demonstrate the change in behavior of weaned piglets over time in two different groups (littermates and piglets from different litters) after mixing. Two weaned groups of piglets (72 individuals in all) housed either with littermates or with foreign piglets (6 individuals in 1.8 m×1.4 m pens, 28°C±1°C temperature) were observed with the aid of video technology for 9 consecutive hours on days 1, 2, and 3 after mixing. The behaviors of the weaned piglets in the control and treatment groups were significantly different among the days after mixing. Piglets were, however, more active and aggressive in the groups with foreign piglets. This study reveals a lower level of agonistic behavior in groups of piglets that came from the same litter.

Ecological factors influencing the winter abundance of mammals in temperate forest

Abstract. We examined the ecological factors influencing winter abundance of mammals in the natural deciduous forest and the Japanese larch, Larix leptolepis, plantation in Mount Maehwa, Hongcheon, South Korea. We counted the tracks of five mammal species — the Korean hare, Lepus coreanus; the raccoon dog, Nyctereutes procyonoides; the Siberian weasel, Mustela sibirica; the water deer, Hydropotes inermis and the wild boar, Sus scrofa — in the snow from November 2013 to February 2014. We showed that the mean basal area, canopy cover and shrub cover were significantly higher in the Japanese larch plantation than in the natural deciduous forest. The winter abundances of Korean hares, raccoon dogs and water deer were higher in the Japanese larch plantation than in the natural deciduous forest. The results of stepwise analysis revealed that the winter abundances of four species were significantly correlated with ≥ 1 of the habitat variables. The winter abundances of Korean hares, water deer and wild boars were significantly correlated with shrub cover. The winter abundances of Korean hares, raccoon dogs and wild boars were significantly correlated with fallen logs; and the winter abundance of water deer was significantly correlated with canopy cover. For all of the investigated species, the preferred winter habitat was the Japanese larch plantation, with dense shrub cover and high number of fallen logs. Our results indicate that for planning conservation and forest management strategies for mammal species, the preferred forest habitat variables must be taken into consideration.

Influence of tree thinning on the abundance of mammals in a Japanese larch Larix kaempferi plantation

ABSTRACT We examined the influence of tree thinning on the abundance of mammals in a Japanese larch Larix kaempferi plantation in Mt Gariwang, Pyeongchang, South Korea. In 2014 and 2015, from April to October, we recorded the presence of tracks as a proxy for abundance, for the following seven mammalian species: Korean hare Lepus coreanus, raccoon dog Nyctereutes procyonoides, Siberian weasel Mustela sibirica, Eurasian badger Meles meles, water deer Hydropotes inermis, roe deer Capreolus pygargus, and wild boar Sus scrofa. We also assessed how the intensity of tree thinning affected vegetation cover; there were significant differences in number of standing trees, basal area, coverage of vegetation layers, and number and volume of downed trees among the control, moderately thinned, and intensively thinned stands. We found significant differences in the abundance of tracks among the stands for three mammal species. In four mammal species, the abundance of track was significantly correlated with volume of downed trees, coverage of ground vegetation, number of downed trees, and number of standing trees, according to stepwise analysis. The presence and abundance of mammals is linked to habitat variables and forest managers should consider how habitat modifications will affect wildlife.

Effect of begging call playbacks on growth of great tit, Parus major, nestlings

This study was conducted to clarify the effects of begging call playbacks on the growth of great tit, Parus major, nestlings in artificial nest boxes. The mean body mass of nestlings significantly differed between the control (60 dB playback intensity), playback 1 (80 dB), and playback 2 (100 dB) groups. However, mean tarsus length was not different based on treatment. The daily body mass and tarsus length gain of nestlings in playback 2 were higher than in the control and playback 1 groups in this study. Further long-term research is needed to understand the relationship between begging behavior of nestlings and parental care in the great tit.

Characteristics of mammal abundance relative to habitat variables in temperate forests

This study was conducted to examine the characteristics of mammal abundance that are related to habitat variables in natural deciduous forest and Japanese larch (Larix leptolepis) plantation in the national forest of Mt. Gariwang, Pyeongchang, Korea. Habitat variables differed between forest types. We counted the mammal trails of Korean hares (Lepus coreanus), raccoon dogs (Nyctereutes procyonoides), Siberian weasels (Mustela sibirica), Eurasian badgers (Meles meles), water deer (Hydropotes inermis) and wild boars (Sus scrofa) during the study period. Eurasian badgers, water deer, and wild boars exhibited one or two significant correlations with coverage of understory, downed trees, and coverage of overstory, as determined using a stepwise approach. Habitat variables could be used as predictors of mammal abundance, and thus forest managers should consider such variables in mammal conservation and management activities.

Bill color characteristics and body mass of the great tit (Parus major) nestling

This study was conducted to examine the bill color and body mass of great tit (Parus major) nestlings in artificial nest boxes. In this study, the nestlings with yellow bills had a higher body mass on the second and eighth day after hatching. Moreover, the brightness values of the color of the bill on the eighth day after hatching were negatively correlated with the body mass of the chicks. Our experiment shows that the color of the bill of the nestling could accurately signal the quality of the chick. Moreover, carotenoid-based colors play an important role in avian communication. Study of carotenoid-based colors in the great tit would be required in the future.

Bat populations in lowland dry evergreen forests of the Central Cardamom Protected Forest in Cambodia

This study was conducted to clarify the characteristics of bat populations in lowland dry evergreen forests of the Central Cardamom Protected Forest in Cambodia during the rainy seasons of 2011–2013 and the dry seasons of 2012–2013. In five study sites of the forest, data from 160 individuals of six bat species were recorded. The Sunda short-nosed fruit bat (Cynopterus brachyotis Sunda) was the most dominant species in all study sites. Most captured bats were adults, and captured females outnumbered captured males. In this study, populations of the bats, except for that of the Sunda short-nosed fruit bats, were not stable. Therefore, forest loss and degradation should be prohibited in the study areas to ensure stable bat populations. Further studies are required to investigate the ecological characteristics of fruit bats in various forest types for the conservation of the mammals and their habitats.

Breeding ecology of tits using artificial nest boxes in coniferous and deciduous forests in Mt. Namsan, Seoul Metropolitan, Korea

This study was conducted to elucidate the breeding ecology of tits in artificial nest boxes in both deciduous and coniferous forests located in Mt. Namsan, Seoul Metropolitan, Korea, from March to June 2012. Great tit Parus major and varied tit P. varius both used the artificial nest boxes in the coniferous forest, but only the great tit used the artificial nest boxes in the deciduous forest for breeding. There were 27 artificial nest boxes in the coniferous forest and 17 in the deciduous forest. The rate of breeding success was 6.7–26.7% for both study sites. The clutch size of varied tits was less than that of great tits. Brood size, incubation period and nestling care period were the same for great and varied tits in the coniferous forest. There were no differences related to forest type for number of breeding pairs, breeding behaviors, egg measurements, and results of hatching, fledgling and breeding for great tits bred in artificial nest boxes. Long-term ecological research on food availability and breeding success of tits is needed for the conservation of these birds and their habitats.