Some Aspects of the Ecology of Ixobrychus Bitterns Nesting in Malaysia Ricefields

Abstract

Data were collected on the behavioral ecology of Cinnamon Bitterns (Jxobrychus cinnamomeus) and Yellow Bitterns (I. sinensis) in Malaysia. Data on courtship displays of both species and activity rates of I. cinnamomeus show that aerial activity tends to be crepuscular. While diets are similar, with fish, amphibians and invertebrates taken, I. cinnamomeus tends to take larger aquatic prey, and I. sinensis appears to take terrestrial invertebrates. I. cinnamomeus nests only in ricefields, whereas I. sinensis nests mainly in bushes and small trees surrounding ricefields. This conforms with published accounts of the species which suggest that I. sinensis is generally more catholic in its choice of nest site and tends to nest higher in available vegetation. Received 19 March 1992, revised 5 March 1993, accepted 9 March 1993.