9 thoughts on “Rarotonga Starling (Aplonis cinerascens)”
The wooded areas where the starling is the most abundant are limited due to agricultural practices and introduced species. Additionally, the introduced rats are still a risk for the species, as shown by the higher abundance of the starling in the valley where the rats have been controlled. Regarding the fact the species is endemic to a single small island, and in the light of the current threats mentioned above, I would not recommend a category change for this species.
The inland forest of Rarotonga has not significantly contracted in the last 40 years, the main change is that slope fernlands have been replaced by Albizia forest. The bird is very widespread in the broad-band of Slope Forest, usually noticed in small clusters in the late afternoon. Although rats probably have an effect on breeding success this would have been constant over many many years, and over my 40 years here I have not suspected any decline in starlings. Increased housing on some outer slopes and ridges probably slightly reduces suitable habitat by removing some native trees and creating more myna territories. Nevertheless, I think Near Threatened would be a suitable category.
I agree that there has been little change in the area of extent of inland forests on Rarotonga in the 36 years I have been visiting almost annually. Predation on this single-island endemic by introduced ship rats (Rattus rattus) is likely to be the main population driver/ suppressor, with potential for competition for nest sites from Indian Mynas (Acridotheres tristis) and the rapidly-growing population of the Jungle Myna (A. fuscus) that has recently established on Rarotonga, and the ever-present risk of a direct hit on Rarotonga by a severe tropical cyclone.
I have the impression, but no quantitative data, that i’oi numbers have increased in the Takitumu Conservation Area (TCA) following annual rat control since 1989, but I encounter them much less frequently away from the poisoned area. We have individually colour-banded about ten birds but, despite checking many birds, we have never resighted any, so I don’t know whether they are highly mobile or there are more than I think.
I would be very surprised if there were as many as 2350 mature individuals (0.5/ha of forest habitat) on Rarotonga, though densities may approach that level in the TCA.
I agree with Alice Cibois’ cautious approach and would recommend leaving them classified as Vulnerable.
Many thanks to everyone who has contributed to this discussion. We greatly appreciate the time and effort invested in commenting. The window for consultation is now closed and we are unable to accept any more comments until 26 June 2023. We will now analyse and interpret the new information, and we will post a preliminary decision on this species’ Red List status on this page on 26 June 2023, when discussions will re-open.
It is acknowledged that this species is limited by several factors, however, according to IUCN guidelines, its current listing as Vulnerable under Criterion D2 can only be maintained if there is a plausible threat that could drive the species to CR or EX within a very short time period (e.g. within one or two generations) with a substantial possibility of this occurring. Although its range is highly restricted, the species has persisted despite cyclones historically. It thus appears unlikely to be capable of rapidly becoming CR or EX due to such stochastic events, though further input and comments on this are welcome. Based on available information therefore, our preliminary proposal for the 2023 Red List would be to adopt the proposed classifications outlined in the initial forum discussion unless there is information to suggest that rapid deterioration to CR or EX is indeed a plausible scenario.
There is now a period for further comments until the final deadline on 2 July 2023, after which the recommended categorisations will be put forward to IUCN.
The final 2023 Red List categories will be published on the BirdLife and IUCN websites in December 2023, following further checking of information relevant to the assessments by both BirdLife and IUCN.
Te Ipukarea Society is the BirdLife partner in the Cook Islands. We believe that the bird should remain as vulnerable, as it is a single island endemic, and on a global scale, a very small island at that, at 67 sq.km.
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While we have not had any devastating cyclones recently, we will. The “one in one hundred year” events will happen, and could have a devastating impact on I’oi and other birdlife.
We concur with the comments by Dr Hugh Robertson, an ornithologist with a great deal of experience in Rarotonga, and Dr Alice Cibois
All comments on recent status appear to be based on observations only, There have been no comprehensive surveys for I’oi for quite a long time. We are planning to do one in the next 2 years, and are working on resources to do that
I did research on I’oi for my Masters degree in the early 2000s. I was also part of the team that helped Carly Easby gather data for her research. There has been no long term systematic monitoring and assessment of I’oi on Rarotonga. I’oi are shy and inconspicuous birds making it hard to get a good picture of their status. Further work on the I’oi over a longer period of time is required to gain a better understanding on their status . Like Alice and Hugh I do not recommend a change in their category.
Many thanks to everyone who has contributed to this discussion. We greatly appreciate the time and effort invested in commenting. The window for consultation is now closed and we are unable to accept any more comments. We will analyse and interpret the information, and we will post a final decision on this species’ Red List status on this page on 10 July 2023.
Recommended categorisation to be put forward to IUCN
The final categorisation for this species has changed: It is acknowledged that the population remains susceptible to stochastic events and as such, D2 is added to the criteria string: the species is restricted in such a way that a plausible future threat could drive it to EN or VU in a very short time. However, the species has persisted despite cyclones historically and in the absence of evidence to suggest that rapid deterioration to CR or EX is a plausible scenario, it is only thought to approach, and not meet, the threshold for listing as Vulnerable under this Criterion. Rarotonga Starling is therefore recommended to be listed as Near Threatened, approaching the threshold for listing as threatened under Criteria B1b(iii)+2b(iii); D2.
Many thanks for everyone who contributed to the 2023.2 GTB Forum process. The final 2023 Red List categories will be published on the BirdLife and IUCN websites in December 2023, following further checking of information relevant to the assessments by both BirdLife and IUCN.
The wooded areas where the starling is the most abundant are limited due to agricultural practices and introduced species. Additionally, the introduced rats are still a risk for the species, as shown by the higher abundance of the starling in the valley where the rats have been controlled. Regarding the fact the species is endemic to a single small island, and in the light of the current threats mentioned above, I would not recommend a category change for this species.
The inland forest of Rarotonga has not significantly contracted in the last 40 years, the main change is that slope fernlands have been replaced by Albizia forest. The bird is very widespread in the broad-band of Slope Forest, usually noticed in small clusters in the late afternoon. Although rats probably have an effect on breeding success this would have been constant over many many years, and over my 40 years here I have not suspected any decline in starlings. Increased housing on some outer slopes and ridges probably slightly reduces suitable habitat by removing some native trees and creating more myna territories. Nevertheless, I think Near Threatened would be a suitable category.
I agree that there has been little change in the area of extent of inland forests on Rarotonga in the 36 years I have been visiting almost annually. Predation on this single-island endemic by introduced ship rats (Rattus rattus) is likely to be the main population driver/ suppressor, with potential for competition for nest sites from Indian Mynas (Acridotheres tristis) and the rapidly-growing population of the Jungle Myna (A. fuscus) that has recently established on Rarotonga, and the ever-present risk of a direct hit on Rarotonga by a severe tropical cyclone.
I have the impression, but no quantitative data, that i’oi numbers have increased in the Takitumu Conservation Area (TCA) following annual rat control since 1989, but I encounter them much less frequently away from the poisoned area. We have individually colour-banded about ten birds but, despite checking many birds, we have never resighted any, so I don’t know whether they are highly mobile or there are more than I think.
I would be very surprised if there were as many as 2350 mature individuals (0.5/ha of forest habitat) on Rarotonga, though densities may approach that level in the TCA.
I agree with Alice Cibois’ cautious approach and would recommend leaving them classified as Vulnerable.
Many thanks to everyone who has contributed to this discussion. We greatly appreciate the time and effort invested in commenting. The window for consultation is now closed and we are unable to accept any more comments until 26 June 2023. We will now analyse and interpret the new information, and we will post a preliminary decision on this species’ Red List status on this page on 26 June 2023, when discussions will re-open.
Preliminary proposal
It is acknowledged that this species is limited by several factors, however, according to IUCN guidelines, its current listing as Vulnerable under Criterion D2 can only be maintained if there is a plausible threat that could drive the species to CR or EX within a very short time period (e.g. within one or two generations) with a substantial possibility of this occurring. Although its range is highly restricted, the species has persisted despite cyclones historically. It thus appears unlikely to be capable of rapidly becoming CR or EX due to such stochastic events, though further input and comments on this are welcome. Based on available information therefore, our preliminary proposal for the 2023 Red List would be to adopt the proposed classifications outlined in the initial forum discussion unless there is information to suggest that rapid deterioration to CR or EX is indeed a plausible scenario.
There is now a period for further comments until the final deadline on 2 July 2023, after which the recommended categorisations will be put forward to IUCN.
The final 2023 Red List categories will be published on the BirdLife and IUCN websites in December 2023, following further checking of information relevant to the assessments by both BirdLife and IUCN.
Te Ipukarea Society is the BirdLife partner in the Cook Islands. We believe that the bird should remain as vulnerable, as it is a single island endemic, and on a global scale, a very small island at that, at 67 sq.km.
.
While we have not had any devastating cyclones recently, we will. The “one in one hundred year” events will happen, and could have a devastating impact on I’oi and other birdlife.
We concur with the comments by Dr Hugh Robertson, an ornithologist with a great deal of experience in Rarotonga, and Dr Alice Cibois
All comments on recent status appear to be based on observations only, There have been no comprehensive surveys for I’oi for quite a long time. We are planning to do one in the next 2 years, and are working on resources to do that
I did research on I’oi for my Masters degree in the early 2000s. I was also part of the team that helped Carly Easby gather data for her research. There has been no long term systematic monitoring and assessment of I’oi on Rarotonga. I’oi are shy and inconspicuous birds making it hard to get a good picture of their status. Further work on the I’oi over a longer period of time is required to gain a better understanding on their status . Like Alice and Hugh I do not recommend a change in their category.
Many thanks to everyone who has contributed to this discussion. We greatly appreciate the time and effort invested in commenting. The window for consultation is now closed and we are unable to accept any more comments. We will analyse and interpret the information, and we will post a final decision on this species’ Red List status on this page on 10 July 2023.
Recommended categorisation to be put forward to IUCN
The final categorisation for this species has changed: It is acknowledged that the population remains susceptible to stochastic events and as such, D2 is added to the criteria string: the species is restricted in such a way that a plausible future threat could drive it to EN or VU in a very short time. However, the species has persisted despite cyclones historically and in the absence of evidence to suggest that rapid deterioration to CR or EX is a plausible scenario, it is only thought to approach, and not meet, the threshold for listing as Vulnerable under this Criterion. Rarotonga Starling is therefore recommended to be listed as Near Threatened, approaching the threshold for listing as threatened under Criteria B1b(iii)+2b(iii); D2.
Many thanks for everyone who contributed to the 2023.2 GTB Forum process. The final 2023 Red List categories will be published on the BirdLife and IUCN websites in December 2023, following further checking of information relevant to the assessments by both BirdLife and IUCN.