The Javan hawk-eagle: misconceptions about rareness and threat

The Javan hawk-eagle ( Spizaetus bartelsi) is a threatened raptor endemic to the densely populated island of Java. Historically very little is known about its biology. Recent surveys showed that the population size has been underestimated in the past. The breeding population is estimated to be 137–188 pairs with a total of 600–900 birds and confirmed presence in 22 discrete forest blocks throughout Java. The eagles were present in isolated forest fragments as small as 3000 ha. Good dispersal abilities in juveniles, a niche width in habitat, which is broader than previously assumed, and rather opportunistic feeding behaviour are believed to mitigate the effects of habitat fragmentation. The appointment of the eagle as a flagship species involves serious risks, as it appears to have put the species on the list of rare birds that are in great demand with malevolent aviculturists.