Regional And Local Extirpation Of A Formerly Common Sundaic Passerine, The Straw-Headed Bulbul Pycnonotus Zeylanicus

The Straw-headed Bulbul Pycnonotus zeylanicus has experienced marked population declines and extirpations due to unsustainable trade and habitat loss across South-East Asia. As a result, the species has been uplisted from Endangered to Critically Endangered on the IUCN Red List within a short span of two years. To ascertain the extent of its regional extirpation, we conducted a thorough review of the scientific literature, complemented with unpublished data, bird trip reports and expert opinion from 1980-2019. Temporal comparisons of occurrence data across 52 sites revealed a likely survival of the species from the pre-2000 into the post-2000 era at only similar to 62% of sites. Albeit substantial, this rate of decline is likely an underestimate of actual survival in 2020, given that the trade volume's greatest expansions have been over the last decade, leading to conservative estimates of survival at only similar to 35-40% of sites when accounting for methodological bias. Our data corroborate recent conclusions that the species is now completely extinct on Sumatra and has significantly decreased across Borneo and Peninsular Malaysia, supporting its recent uplisting. Its last stronghold is the tiny nation of Singapore. We propose a number of conservation recommendations, which include enhanced regulations and enforcement.