Patrick Centurioni

PDF im Hochschulschriften-Service der Universit├Ąt Wien

Habitat requirements and population size of the Javan plover Charadrius Javanicus (Aves, Charadriidae) on Java, Indonesia

Based on current knowledge the distribution of the Javan Plover Charadrius javanicus is predominantly restricted to Java, where it occurs in coastal habitats. This study tried to quantify the species´ habitat requirements and to contribute to estimating its actual population size. During a survey of 0.5 km long transects along a total of 72.5 km of coastline, a total of 218 Javan Plovers corresponding to a mean (± SD) of 1.47 (± 2.64) birds per 0.5 km shoreline was recorded. However, the density of Javan Plovers differed significantly between surveyed coastal regions. Highest abundances were found on the south coast of Java. Furthermore, abundances of Javan Plovers differed significantly between coastal habitats. Wide (>50m), small-grained sandy beaches were the preferred habitat.

The likelihood of Javan Plover occurrence on small-grained beaches increased with beach and flotsam width, while no effect of human disturbance could be found. A weak trend of a decline in Plover numbers towards beaches without any vegetation was found. GLMs indicated that beach width was the best explanatory variable for predicting the occurrence of Javan Plovers in 500 m transects. Along 76 transects of sandy beach habitat including lagoons, a total of 205 Javan Plovers or 5.39 individuals per 1 km shoreline were observed. A total of ca. 2000 birds were estimated for coastal habitats of Java. However, ca. 125 km are located very close to human settlements. Consequently, Javan Plovers may reach a much lower density in some coastal areas. This estimate does not include the part of the population which occurs at fishponds, which may represent an important artificial habitat for this species.

The species does not yet seem to be endangered, nevertheless its populations have to be carefully monitored due to the risk of further coastal development and intensification of fishpond industry becoming a serious threat to the species.