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2015 Myna Survey. Report to inform the Samoan Myna Management Plan
Island and Ocean Ecosystems, BRB
Available Online

Serra. G.

,

Young. S

2015
In May 2015, 74 line transects in three different habitat types (plantation, mixed crops, urban) were surveyed on Upolu and Savai’i islands, Samoa, with an aim of estimating the population size, density and distribution of two invasive bird species, Common Myna (Acridotheres tristis) and Jungle Myna (Acridotheres fuscus). Based on the available literature, the surveyed habitats were identified as preferred foraging habitat for the two myna species. The three habitats make up 24.9% of Samoa’s land area. Survey data were analysed using the Distance program. It was estimated that the population of myna birds occurring in the plantation, mixed crops and urban habitats of Samoa is approximately 158,995 (+- 29,588). Approximately 130,030 (+- 19,837) myna were estimated to live on Upolu and 28,968 (+- 9,751) on Savai’i, across the three habitat types. Survey results also revealed that both species show a significant preference for urban habitat. Jungle Myna were estimated to be the most numerous (population estimate: 133,925 +-24,321), occurring on both islands and in all surveyed habitat types. Jungle Myna seem to have saturated the urban habitat available in Upolu and therefore have proceeded to colonise plantations and mixed crops adjacent to urban areas. Common Myna (population estimate: 23,367 +- 7,612), having reached the shores of Samoa ca. 20 years later than Jungle Myna, show highest density in urban environments. They are concentrated in the north-west section of Upolu, with only a few individuals observed on the east coast of Savai’i.
The Distribution and Abundance of Myna Birds (Acridotheres tristis) and Rimatara Lorikeets (Vini kuhlii) on Atiu, Cook Islands.
Island and Ocean Ecosystems, BRB
Available Online

Heptonstall. R.E.A

2010
The Common Myna Acridotheres tristis was originally introduced to the island of Atiu, Cook Islands, in 1915 to control the Coconut stick insect Graeffea crouanii but it has since become a pest itself. The Rimatara lorikeet Vini Kuhlii or ‘Kura’ was reintroduced, after disappearing from the Southern Cook Islands almost 200 years ago, to Atiu on 24th April 2007 from Rimatara, French Polynesia to create a reserve population due to there being only approximately 1000 birds left on Rimatara. Due to observations of mynas reportedly harassing and attacking adult and juvenile Kura at the nest, an eradication programme was introduced by Gerald McCormack, Director of the Cook Island Natural Heritage Trust (CINHT), in May 2009 to reduce the population size of myna birds to give the Kura a couple of peaceful nesting seasons to help establish a stable population on Atiu. A study by J. Mitchell of the University of Leeds in May/June 2009 estimated a starting count of approximately 6000 myna birds prior to the eradication programme. That survey was followed up in May 2010 using two strategies, the transect method and roost counts. Analysis of transect method counts, using the Distance software, estimate there are approximately 3128 mynas on Atiu. Roost counts were at variance with that figure and estimated only 1280 myna birds. The roost counts estimate of 1280 may be the most accurate because all mynas would be in the winter roosts for heat conservation from May to July alleviating the concern that females and young would be nesting away from the roosts during counts, whereas transect counts may involve recounting the same birds numerous times; a problem minimized by repeating transect counts twice daily and using different transects to cover as much of the expected habitat as possible. Only a limited survey of the population of Kura was possible during this visit to Atiu since almost all available time and logistics were focused on myna surveys. An estimate of the Kura population suggests there are approximately 100 birds, which suggests that since the 2007 introduction the Kura population is thriving on Atiu. However, comparisons with the exponential growth rate model of 184 birds suggest this difference could be due to myna bird harassment despite culling. A more comprehensive survey is recommended perhaps using similar strategies to determine whether the myna has any deleterious effect on the Kura. In July 2010 a new myna bounty was introduced and is proving successful as a further 383 myna birds were culled by the end of July. The Atiu Island Council may decide on complete eradication of the myna to give the Kura full advantage of living on Atiu in the absence of the competitive myna bird.
The distribution and abundance of an invasive species: the common myna (Acridotheres tristis) on Atiu, Cook Islands
Island and Ocean Ecosystems, BRB
Available Online

Mitchell. J.

2009
An invasive alien species are known to cause significant economic and environmental damage. Islands are much more vulnerable to the invasion of invasive alien species, and have higher rates of extinction. In the islands of the South Pacific, there are several species Polynesian land birds which are threatened with extinction due to invasive alien species and human interference. Without any intervention from humans, it is likely that these birds will suffer extinction in the next few decades. The island of Atiu in the Cook Islands (South Pacific) supports a range of avian fauna. In 2007 the Rimitara lorikeet (Vini kuhlii), also known locally as the ‘Kura’ was introduced to Atiu, to make a reserve population, as there were only approximatley 1000 left on the island of Rimitara, French Polynesia. There is concern for this species on Atiu due to the existence of the common myna (Acridotheres tristis). The myna is an aggressive invasive which is one of the world’s worst 100 invasive species. It was introduced to the Cook Islands by the government, with the intention to control the coconut-stick insect (Graeffea crouani), but is now a pest itself. A myna control programme on Atiu is being coordinated and controlled by Gerald McCormack (Cook Islands Natural Heritage Trust), working through George Mateariki, and using funding from various conservation organisations. Poisioning is being carried out by George in order to reduce myna numbers, and a bounty has been set on the birds or for every right foot so that the locals can help as much as possible. This investigation aimed to estimate the total population size on the island to use as a starting count to determine whether the programme is successful or not. Two methods were used which included roost counts to find an estimate of the population, and a transect method using a Distance programme to estimate the number of birds per hectare as well as the level of abundance in various habitat types. The two methods had overlapping results, giving a total estimated range of 3250 to 8460 birds on the island, although it is more likely to be at the higher end of this estimate at around 6000 to7000 birds. Further investigation will need to determine any change in the population size, any changes in habitat composition as well as the impact on the native species, especially the effect on the Kura and its population size.