Feather forensics: tracing Australian parrot trade with online trade analysis, stable isotopes, and citizen science

Abstract

Native Australian parrots are some of the most globally traded pet birds, yet we currently lack the tools to monitor and manage their trade, detect unsustainable harvest, or prevent the establishment of new invasive species. In this thesis, I assessed novel applications of emerging forensic methods to assist in the conservation and biosecurity of the Australian pet parrot trade. The emerging popularity of online commerce for wildlife trade provides a unique opportunity to create a snapshot of domestic pet bird trade. I investigated the species composition and relative abundances of parrots and passerines sold online, and identified the main correlates, which potentially drive a species’ abundance in trade. Australian native parrots were the most frequently traded, yet the species composition in trade were predominantly non-natives. Additionally, high abundance in trade was correlated with species traits associated with higher invasion risk, including cheap prices. Some of the most traded native parrots in Australia were cockatoos (Cacatuidae), which are potentially harvested illegally from the wild and laundered as captive bred. I assessed the application of stable isotope methods to identify differences in diets between cockatoos from captive and wild origins. I created a citizen science project to collect feathers in South Australia and investigated the effects of large geographic range sizes and individual variability on the accuracy of these methods. Stable carbon and nitrogen isotopes confidently classified Galahs (Eolophus roseicapilla); however, I identified that for three Cacatua spp., the diet of wild birds was similar to captive birds, resulting in high rates of misclassification. Rainbow Lorikeets (Trichoglossus molaccanus) were the third most traded native species in online domestic pet trade, and consequently have established multiple invasive populations within Australia. I applied stable isotope methods to identify the isotopic niches of four populations of lorikeets at different stages of the pet-release pathway, to see if these methods could confidently differentiate between recently released pets and established wild populations. The invasive population showed a similar isotopic niche size to the native population, with large overlap with captive birds. In the smaller established and managed population, we were able to confidently identify two recent captive escapees; indicating these methods are applicable to contained established populations and can assist in identifying the most effective management decision-making method to prevent further establishment and spread. These three novel applications of digital and wildlife forensic methods are effective at monitoring Australian parrot trade and managing its associated risks. However, these tools have caveats, and the potential sources of variation and their limitations need to be thoroughly investigated before widespread application. Nevertheless, new tools are important and welcome additions to the wildlife forensic toolbox for assisting in the conservation and biosecurity of trade in native Australian parrots.