This discussion was first published as part of the 2007 Red List update.
Initial deadline for comments: 31 January 2012.
Knobbed Hornbill Aceros cassidix and Sulawesi Hornbill Penelopides exarhatus are both currently listed as Least Concern.
However, a recent reanalysis by Kinnaird and O’Brien (2007) has suggested that both species are declining at rates approaching 30% over ten years/ three generations based on recent and ongoing rates of habitat loss on Sulawesi [16.9% forest loss per ten years during 1985-1997; 36.1% loss per ten years during 1997-2001 based on D. A. Holmes in litt. 1999 and Kinnaird and O’Brien (2007)]. This would qualify them for Near Threatened (almost meeting criteria A2c;A3c). Sulawesi Hornbill may also approach the thresholds under criterion C2b (population approaching 10,000 mature individuals, declining with extreme fluctuations), as MacKinnon and MacKinnon (1980) documented a dramatic crash in the population at Tangkoko in 1978-1979. T. O’Brien and M. Kinnaird (in litt. 2006) have speculated that this may be driven by disease introduced by domestic poultry into wild populations. Does it seem likely that this species undergoes order-of-magnitude population size fluctuations?
Comment and information relevant to the proposal to uplist these species would be welcome.
Kinnaird, M.F. and O’Brien, T.G. 2007. Ecology and Conservation of Asian Hornbills. Univ. Chicago Press
(This discussion was first started as part of the 2007 Red List update)