FitzPatrick Institute Seminar: 'The invasion process: Introduction, establishment, spread and population growth of the Common Myna (Acridotheres tristis) in an Australian city' by Kate Grarock

Exotic species are a major cause of biodiversity loss, with their numbers and impact increasing worldwide. To manage these invasions it is important that decision-makers understand what stage the invasion process is in, approximately how long it will take to reach the next stage and what is the best plan of management for that stage. In this talk I investigate the invasion history of the Common Myna (Acridotheres tristis), in Canberra, Australia, analysing 28 years of community bird survey data to provide valuable information on how quickly the bird can become established, grow in numbers, and spread to new areas. The Common Myna first became established in a Canberra suburb in 1969 with the release of over 100 birds. The population quickly spread to surrounding areas and continued to spread until, 31 years after introduction, it was established in every Canberra suburb,. The mean rate of range expansion was 0.42 km per year. Once established in a region the density of Common Myna birds remained low for an average of 7 years. After this, numbers increased rapidly. Population growth lasted for an average of 13.4 years, with growth slowing or even decreasing after this period. This study will help decision-makers understand the importance of quick action when it comes to dealing with Common Myna invasions. Although the spread of the species can occur relatively slowly, once the population starts to increase, control becomes increasingly difficult.

About the speaker: Kate Grarock holds a degree in Environmental Science from Wollongong University. Currently, she is a PhD student at the Fenner School of Environment & Society at the Australian National University. She is currently researching the introduction and spread of the Common Myna (Acridotheres tristis) in Canberra. Her research has three main components. Firstly, she is investigating the history of the Common Myna invasion in Canberra; secondly, she is exploring competition between native birds and the Common Myna; and thirdly, she is assessing the efficacy of control measures.