Catastrophic ongoing decline in Cambodia's Bengal FloricanHoubaropsis bengalensispopulation

摘要

In 2013 a prediction was made that the South-East Asian subspecies of Bengal FloricanHoubaropsis bengalensis blandiniwould be extinct within 10 years. In 2018 we conducted a survey in the Tonle Sap floodplain, Cambodia, of the last population of Bengal Florican in South-East Asia. We found that the rate of decline in displaying males was 55% over five years, a decline comparable to that recorded between 2005-2007 and 2012. The estimated number of displaying males in 2018 was 104 (95% CI: 89-117), down from 216 (156-275) in 2012. We also conducted surveys by flushing birds in the non-breeding season, which indicated that the sex ratio of males to females is 3:1. We therefore estimate that the total population of adult Bengal Floricans in Cambodia in 2018 was 138 (119-156), makingH. b. blandinithe most threatened bustard taxon. The number of sites that support displaying male Bengal Floricans was reduced from 10 to four between 2012 and 2018. Between 2012 and 2018 we monitored numbers of displaying males in most years at the sites that support 80% of the total population. The only site where numbers of birds are stable is Stoung-Chikraeng Bengal Florican Conservation Area, where there were 44 (25-63) displaying males in 2018. This is the only site that has an ongoing NGO-government conservation programme. Our data indicate that Bengal Floricans are lost from sites when the area of grassland falls below 25 km(2). We found evidence that displaying male Bengal Floricans abandon display territories when grassland is lost, this also creates hope that they may disperse and could colonise newly created habitat. All remaining sites that support Bengal Floricans in Cambodia are imperilled and we outline what must be done to reduce the possibility thatH. b. blandiniwill be extinct by 2023.