The critically endangered helmeted hornbill (Rhinoplax vigil) : threats & conservation

Abstract

The Critically Endangered Helmeted Hornbill (Rhinoplax vigil) provides a case study of a species heavily threatened by human impact, primarily, the illegal wildlife trade and habitat loss. Illegal hunting has led to the number of seized individuals observed over the past 10 years being almost four times higher than the number of wild individuals observed over the past 40 years. This illegal hunting is driven by a demand for their casques to be carved and sold as ornaments illegally. Deforestation across the species’ Southeast Asian range is predicted to have reduced populations by half since 2000 in places like Borneo. These rates will likely be compounded by the 85-90% reduction of predicted species distribution under future climate change scenarios. To reduce the risk of extinction to this species, the IUCN SSC Helmeted Hornbill Working Group (HHWG) released a 10-year Conservation Strategy and Action Plan (2017-2027). This thesis explores the threats to this species and provides scientific research to meet some of the conservation Objectives under the HHWG Actions Plan. In Part I, genetic protocols were provided for potential enforcement and conservation use. In Chapter 1 a wildlife forensic species identification protocol was created for R. vigil based on an 800-bp region of cytochrome-B DNA. A range of methods were presented to obtain DNA sufficient for sequencing and the primers validated for forensic species identification. In Chapter 2, a range of methods were tested to yield sufficient DNA from non-invasive samples of hornbills. There was no change in sequencing success for faecal samples stored up to one month in various storage media. This study highlights a range of methods for obtaining sufficient mtDNA quantity, quality, and sequences from these low-DNA-yield sample types. In Part II, morphological and molecular methods were used to identify the sex ratio of seized casques. I then discuss potential impacts to wild individuals, where a male-skewed sex ratio of seized individuals (M116: F93) was found in Chapter 3. As R. vigil are elusive and difficult to monitor, a species distribution model was used to identify potential distribution across Borneo for monitoring and conservation purposes in Chapter 4. Distance to cropland and forest, and temperature evenness were important drivers of this species distribution. Areas of highly probable current and future distribution were highlighted, and a decline of overall distribution under future (2041-2060) climate scenarios were observed. Finally in Chapter 5, three decades of auction trade data were analysed and market trends explored to understand demand for helmeted hornbill products. They were then compared to seizure and CITES Trade data to provide a bigger picture of the trade. The data suggested that a distinct auction sub-market in illegally traded products developed during the art boom immediately following the 2008 financial crash, with volumes of traded and seized products highly correlated. This demonstrates how vulnerable an endangered species is to swings in demand. By highlighting threats and areas for furthering the conservation of R. vigil, this thesis provides insight into processes fuelling endangered species decline, and tools to mitigate them.