Abstract
I investigated populations of the forest green treefrog Rhacophorus arboreus in relation to changes in its habitat at Kanazawa Castle (Ishikawa Prefecture, Japan) during the period 1984-2012. There were no marked population fluctuations from the 1980s through the mid 1990s, but frog numbers declined rapidly around the turn of the millenium. Population numbers increased again in the middle of the first decade of the new century, and frog densities have been high since about 2010. Although the locations of the ponds that served as breeding sites for this species shifted, because of changes in land-use in the late 1990s, there were always a number of different breeding sites available to the frogs. I did not identify the predominant factors associated with population size variability, but environmental changes in breeding sites probably played a part. Conservation of multiple breeding sites within the habitat range of the forest green treefrog is, therefore, considered important for the protection of this species. Exclusion of alien predators from breeding sites and provision of barrier-free routes between breeding sites are also considered crucial for conservation.
