Java Sparrow (BirdLife species factsheet) is currently listed as Vulnerable on the basis that intense trapping activity is inferred to have caused rapid declines in the population that are suspected to exceed 30% over the previous, current and future ten year periods.
Previously an abundant feature of the Javan and Balinese countryside, various threats appear to have contributed to the collapse of populations throughout the native range of the species. Changes to agricultural practice and near-indiscriminate pesticide usage from the 1990s onwards are likely to have played a role, however the bird has also been heavily trapped and traded for centuries and remaining wild populations are in constant danger of overexploitation (BirdLife International 2001).
In recent years the number of locations with populations appears to have declined further. On Java there are two breeding colonies in Yogyakarta, a colony at a residential complex in central Java, continuing recent reports from Baluran National Park and a location on Madura Island where the chicks are harvested (Eaton et al. 2015). The continued persistence and status of several other colonies established at government complexes and some other hotels is uncertain, though Eaton et al. (2015) mention that two have been lost through renovation. On Bali birds are still present in Bali Barat National Park, and there are several locations in urban areas with small groups, many of which may have escaped from captivity (BirdLife International 2001). Fewer than 100 individuals are considered to remain at any of these locations and there seems a very low likelihood of exchange of individuals between these regions. Indeed it does appear that the rapid declines cited in Threatened Birds of Asia (Birdlife International 2001) have continued to the present day.
Considering this small number of locations and the apparently low numbers of individuals present at each of the locations, has there been any recent attempt to quantify the overall population occurring in the wild within the historic native range of the species? Is an assessment of the total number of mature individuals now being below 2,500 reasonable? If so, the species would now qualify as Endangered under criterion C2a(i). Note that under the IUCN Red List guidelines only populations within the native range of a species should be used for an assessment of the status of a species.
Comments highly desired!
BirdLife International 2001. Threatened birds of Asia: the BirdLife International Red Data Book. Cambridge, UK: BirdLife International.
Eaton, J.A., Shepherd, C.R., Rheindt, F.E., Harris, J.B.C., van Balen, S. (B.), Wilcove, D.S. and Collar, N.J. 2015. Trade-driven extinctions and near-extinctions of avian taxa in Sundaic Indonesia. Forktail 31: 1-12.