Eradication of a highly invasive bird, the Common MynaAcridotheres tristis, facilitates the establishment of insurance populations of island endemic birds

Abstract

Summary Common Myna Acridotheres tristis is considered to be among the world’s most damaging invasive species through disturbance, predation, competition pathogen introduction to native birds and other taxa. Claimed impacts on native birds have often been based on anecdotal reports. More substantive evidence of interference with small-island endemic birds has been reported, but impacts have rarely been quantified or subjected to experimental manipulation. On Denis Island (Seychelles), up to 10% of Seychelles Warblers Acrocephalus sechellensis, and small numbers of Seychelles Fodies Foudia sechellesis and Seychelles Paradise Flycatchers Terpsiphone corvina had head injuries following myna attacks, stimulating an eradication of the mynas. Populations of four species of Seychelles’ endemic birds, introduced to the island to establish insurance populations, were estimated before, during and after the completion of the eradication, permitting assessment of the impact of myna removal on populations of the endemics. Numbers of all four endemics increased following introduction, but increases in the numbers of Seychelles Magpie Robins Copsychus sechellensis and Seychelles Paradise Flycatchers accelerated after >90% of the mynas had been removed. All endemic populations continued to increase during and after completion of the eradication in 2015, and injuries to Seychelles Warblers, Seychelles Fodies, and Seychelles Paradise Flycatchers ceased. Habitat management within a designated conservation zone on the island, into which the endemics were released and subsequently spread to occupy most of the island, also contributed to the endemic birds’ global populations and to their improved conservation status. This study confirms that mynas negatively impact small island populations of endemic birds and suggests that their potential impact has been underestimated. Myna eradication should be considered vital before endangered endemic birds and other taxa susceptible to their negative impacts are translocated to small islands for conservation reasons.

A major myna problem; invasive predator removal benefits female survival and population growth of a translocated island endemic

“…rats) from the same area (Blanvillain 2020;Tindall 2007). Population growth of Seychelles paradise flycatchers (Terpsiphone corvina) and Seychelles magpie robins on Denis (both introduced in 2008 and susceptible to myna attacks) also increased after the myna removal, suggesting a positive effect on the establishment of those populations (Feare, Bristol and Van De Crommenacker, 2022). Crucially, our study of Seychelles warblers goes further in showing that i) causes of low population productivity (i.e.…”

The genome of a globally invasive passerine, the common myna, Acridotheres tristis

“…1b ). 12–14 The common myna’s ecological impacts are particularly pronounced in island ecosystems 15 , 16 and have also been studied within Australia, New Zealand, and South Africa, where their widespread geographic coverage has elicited research interest into their invasion history and impacts. 14 , 17–19 This species has been the focus of ecological and conservation research owing to their aggressive territorial behaviour that may exclude native avian species from nesting structures and foraging areas, 20–22 though evidence for this is mixed in some environments.…”

Tracing the introduction of the invasive common myna using population genomics

“…In addition, mynas may also impact human health and livelihood through the spread of disease, noise pollution, and property damage (Yap et al 2002 ; Parkes 2006 ; Saavedra 2009 ; Clark et al 2015 ). Eradication of mynas on islands has been found to positively impact the native fauna, for example, the increase in numbers of the native Seychelles magpie robins and Seychelles paradise flycatchers accelerated after removal of 90% of mynas from Denis Island, Seychelles (Feare et al 2021 ).…”