Spread of the invasive Java']Javan myna along an urban-suburban gradient in Peninsular Malaysia

Invasive species can spread rapidly at local and national scales, resulting in significant environmental and economic impacts. Rapid urbanisation and deforestation can accelerate the spread of invasive species and depress populations of native species. We studied the pattern of spread of the Javan myna Acridotheres javanicus, an introduced species in Peninsular Malaysia that has benefited greatly from urbanisation over the past 40 years (1981-2020). We used the online database eBird-a citizen science project-to build a species distribution model using data collected by birdwatchers from discrete locations and visits. We show that the invasive Javan myna range has drastically increased in Peninsular Malaysia over the past 40 years following the escape and release of captive individuals. The number of mynas continued to increase over four 10-year observation phases. Notably, there was a particularly drastic increase in 2011-2020 period, with 56,201 Javan myna observations. The cumulative Javan myna range across Peninsular Malaysia was 28,855 km(2) in 2011-2020, with the majority of this distribution occurring in two major metropolitan cities: greater Kuala Lumpur (including the suburban area, Selangor) and Johor. In urban areas of Peninsular Malaysia, the Javan myna spread rate increased by approximately 44.4% from the 2001-2010 period to the 2011-2020 period. A species distribution model applied to the entirety of Peninsular Malaysia showed that urban land use was related to the model. The generalised linear model showed a significant positive relationship between urban area expansion and Javan myna abundance. We effectively map the spread of the highly invasive Javan myna and highlight the need for an improved management plan that includes a risk prediction analysis and management strategies for this species. Such dynamic mapping and analyses is crucial for better understanding of the mechanisms that lead to the persistence of urban biodiversity.