Population Status, Habitat Use and Breeding Success of Asian Openbill (Anastomus Oscitans) in Lami Tal and Tikauli Tal, Chitwan

Abstract

The Asian Openbill (Anastomus oscitans) is the vulnerable species of birds. Its population has been declining in the Chitwan. Present study was carried out to determine the population size, habitat use and breeding activities in Lami Tal and Tikauli Tal, Chitwan. Road transect surveys methods were used to collect data of Asian Openbill and Jacknife technique was used to calculate the estimated population size. The conservation threats were analyzed by field surveys and questionnaire surveys.

The maximum estimated population size of Asian Openbill was 118 in Tikauli Tal area and 151 in Lami Tal area. Asian Openbill was found to use the wetlands for nesting, foraging and feeding purpose. The total nest recorded during the study was all in the wetland area. The feeding grounds surveyed were all the wetlands as rice fields as rice fields, marshy areas etc. Saj (Terminalia tomentosa), Simal (Bombax ceiba) and Palas (Butea monoserma) were extensively used by Asian Openbills for nesting purpose.

Using active nests as primary unit, the breeding success of Asian Openbill was 87.5% in Lami Tal area and Tikauli Tal area. Two types of results were found from the different sites. No any significant in flock size of Asian Openbill was found between nesting and post-nesting phase (tcal=2.24<ttab=2.31) in Lami Tal while there was significant difference in flock size of Asian Openbill between nesting and post-nesting phase (tcal=2.71>ttab=2.31) in Tikauli Tal.

Remarkable decline in the no. of Asian Openbill may be due to the habitat destruction, lack of food, natural calamities, unfavourable condition and use of chemical fertilizers. Raising of awareness among the local people, plantation of nesting trees in wetland area and providing information about the ecological role of Asian Openbills in controlling the paddy pests.