Dynamic wetland mosaic environments and Asian openbill habitat creation in peri-urban Bangkok

Abstract

This study examined the spatial relationships between various types of wetland and the distribution of Asian openbills (Anastomus oscitans) as an indicator species in a peri-urban industrial area of Bangkok. We (1) mapped the study area by using a time series of aerial photographs combined with field validations, (2) conducted a 2-year line census of Asian openbills in the field, (3) interviewed local farmers and residents about Asian openbill populations and spatial distributions, and (4) conducted an overlay analysis to statistically identify land-use factors related to spatiotemporal changes in the Asian openbill population and distribution. We found that the number of ponds increased from 1980 to 1999 and then decreased from 1999 to 2010, but the remaining ponds were relatively temporally stable in their numbers and volumes. Paddy fields were primarily replaced by aquaculture ponds, and excavated soil was used as fill in adjoining built-up areas. The number of coconut, banana, mango and other trees planted around the ponds increased during the period, providing Asian openbill habitat. The openbills fed in the remaining paddy fields, and the simultaneous existence of various rice cultivation stages in the area provided a stable year-round source of food. Overall, the results indicated that this expanding urban–rural mosaic landscape could include further spatial distribution of Asian openbills in the future. This study of Asian openbills reveals just one example of the ecosystem services provided by developments creating pond–fill landscapes, and the methods used may be applicable in other similar continental delta regions.