Aliens Newsletter - ISSG

Eradication of invasive Mynas from islands. Is it possible?
Susana Saavedra
Introduced and breeding populations of common
Mynas (Acridotheres tristis) have been managed
on six different islands in the past ten years
(1999/2009) by the author. Permanent
surveillance and the set up of a Quick Response
Team (QRT) have lead eradications or control of
those populations.
The QRT has stopped the myna invasion in
Tenerife, Gran Canaria and Mallorca,
eradicating their wild breeding populations at its
beginning when the number was low and before
populations grew and spread within the territory
or other islands, and with an excellent cost
efficient budget.
Control efforts, the first campaign in
Fuerteventura were really successful, covering
80% of the small bird island population. In St
Helena, with around 9.000 mynas, this ratio was
lower, reaching 4%; and in Ascension Island, the
56% of the myna population was controlled and
removed from the environment by trapping.
Introduction
From the ten known species of Acridotheres, only
the common myna (Acridotheres tristis Linnaeus,
1766) has been catalogued by the IUCN List of the
100 Worst Invasive Species worldwide (Lowe et al.
2000).
The common myna is a very intelligent bird and
highly adaptable to the environment where it gets
installed. It’s omnivorous diet ranges from eggs to
chicks of terrestrial and marine local birds (Huges
2008), insects, reptiles, nectar, seeds of invasive
plants and even rests of marine food, which allows
it to find food on human waste, crops or areas with
cattle or domestic animals. Mynas are excellent human
commensals. Their instinct of breeding in
holes force them to compete directly with native local
bird species that use this niche and which get displaced
(Pell and Tidemann 1997), defend aggressively
their territory, food and water sources.
Common mynas are very noisy, especially when
they wake up at sunrise and when they congregate
to sleep in the roost sites in the evenings. Myna
species are able to spread parasites and diseases between
birds (Orueta 2002) and to other vertebrate
species [H5N1 (Darrell et al. 2007)] including humans
[Salmonella (Allan 2009), Ornithonyssus bursa
(Manpreet et al. 2009) and Exophiala dermatitidis
(genotype B) (Sudhadham et al. 2008)].
These calamities occur in a very dangerous form
when common mynas invade insular environments.
Oceanic islands are known to be even more delicate,
as it is known that they house numerous endemism
which represent a great ecological fragility associated
both with its reduced territory and the simplicity
of its biological aboriginal communities. Therefore,
the priority target in conservation for insular environments
is eradication or control of exotic invasive
species, though it might not be voluntarily assumed
by local authorities. The control or eradication efforts
which took place in Seychelles – eradication
project in Cousin Island (Millett et al. 2005) and in
Ascension, where 40 mynas where not a target specie
during a cat eradication campaign in 2004 (Hughes
et al. 2008), have not been conclusive. Obviously it
is a complicated challenge so much that, its viability
has been questioned.
In this contribution six projects are shown where the
author has worked with this specie (1999-2009),
having achieved its eradication in some islands, and
control in some others. From the experience gained
it stands out some practical aspects and recommendations
that could be useful to other people who
must fight this dangerous specie.
The six islands cases
The eradication and control campaigns have been
done in six islands, most of them with a volcanic
origin and in the Atlantic Ocean (except the island
of Mallorca, with a continental origin, in the
Mediterranean Sea). Table I resumes interesting data
from these territories.
40 29/2010