FLUCTUATION OF THE HOLOCENE BAT POPULATION EVIDENCED BY ANALYSIS OF IMMOBILE ELEMENTS OF THE BAT GUANO FROM CARBONATE CAVES, KOREA

Organic-rich bat guano profiles were collected from the carbonate caves located along the eastern coast of Korean Peninsula: Gossi Cave (40 cm high and 200 cm wide dome), Baegryong Cave (50 cm high and 100 cm wide dome), and Seongryu Cave (20 cm high platform). The Gossi guano was calculated to have been deposited from 3,097 to 4,200 BP yr, Baegryong guano from 3,650 to 7,150 BP yr, and Seongryu guano from 150 to 6,000 BP yr. Chemical elements of the three bat guanos were analyzed using XRF. Among them, specific immobile elements (Al₂O₃, SiO₂, and TiO₂) were identified from all the bat guano profiles, showing very similar trend from bottom to top layers. Such immobile elements are those of clastic sediments blown into the caves as dust. The amount of such immobile elements is closely related with deposition rate of the bat guano; low concentration of those elements implies rapid deposition rate while high concentration represents slow deposition rate of bat guano profiles. Basically, deposition rate of bat guano is controlled by the population density of bat lived in the cave. The amount of immobile elements of the Gossi Cave, for example, tends to increase toward top layer with a sudden decrease at the middle-upper layer (4,000 BP yr). It is, thus be concluded that bat population experienced fluctuation showing an decrease from 6,150 to 4,150 BP yr and sudden increase at 4,000 BP yr, followed by constant decrease to 3,150 BP yr.