This discussion was first published as part of the 2023 Red List update. At the time a decision regarding its status was pended, but to enable potential reassessment of this species as part of the 2024 Red List update this post remains open.
Swinhoe’s Rail (Coturnicops exquisitus)
For several years, my colleagues and I have been undertaking a detailed review of the past and present distribution and status of C. exquisita, including a restudy of museum specimens (birds and eggs). The study will be finished this year (2023). Our preliminary results do not support changing the status of C. exquisita from VU to LC. I suggest to postpone any decision until our study is finished.
I agree that the species might be more widespread in Russia west of the previously known range, but this suggestion is currently only based on our observation of one singing male at Lake Baikal (Anisimova et al. 2019). Despite the fact that the vocalisations of this species were described already in 2017, the number of newly discovered occurrences of this species in Russia since then is still close to zero.
In the Amur region, the species is only known from a handful of places, and nowhere in very high densities. Much of the habitat where the species was found in the Amur region is subject to increasing fire frequencies. Frequent fires destroy the old tussocks and limit vegetation structure in the wetlands, which could be a serious threat for Swinhoe´s Rail (see e.g. Heim et al. 2019, https://link.springer.com/article/10.1007/s10531-019-01746-3).
It is also not clear whether the Japanese Swinhoe´s Rail population belongs to the same (sub)species as the population on the mainland, for which a genetic study is under way which hopefully will be published this or next year.
I would therefore suggest to postpone the decision, until further evidence is available.
Preliminary proposal
Based on comments made on the Forum that additional information is forthcoming in the next 12 months, our proposal for the 2023 Red List is to pend the decision on this species and keep the discussion open until 2024, while leaving the current Red List category unchanged in the 2023 update.
There is now a period for further comments until the final deadline on 12 February 2023, after which the recommended categorisations will be put forward to IUCN.
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.
Preliminary proposal
Based on available information, our proposal for the 2023 Red List is to pend the decision on this species and keep the discussion open, while leaving the current Red List category unchanged in the 2023 update.
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.
This species has recently received several reports of the wintering distribution and the detailed status in Japan.
Takahashi et al. 2018, https://doi.org/10.3838/jjo.67.109
Fukuda et al. 2019, https://doi.org/10.11211/birdresearch.15.A1
Kitazawa and Yoshioka 2021, https://doi.org/10.11211/birdresearch.17.S13
Matsumiya and Numano 2022, https://doi.org/10.11211/birdresearch.18.A87
The species has been found in a wider range than previously known. However, there are not many suitable habitats and continues to decline. For example, we found a small number of wintering habitats for this species in the Kinki region of Japan in 2021, one-third of which has since been lost or will be lost to development.
This species’ habitat is likely disappearing without the potential effects for the species being fully understood, and populations are likely declining as habitat declines. I would therefore suggest to postpone the decision, until the rate of decline in the population is known.
Preliminary proposal
Based on available information, our proposal for the 2024 Red List is to pend the decision on this species and keep the discussion open, while leaving the current Red List category unchanged.
There is now a period for further comments until the final deadline on 18 February 2024 after which the recommended categorisations will be put forward to IUCN.
The final 2024 Red List categories will be published on the BirdLife and IUCN websites in December 2024, following further checking of information relevant to the assessments by both BirdLife and IUCN.
While I am not aware of any new data on distribution or abundance of this species (including no confirmation that the species regularly occurs as far west as Lake Baikal), there is a new genetic study on the species, available here as a pre-print: https://doi.org/10.1101/2023.09.27.559751
What I think is relevant fot this assessment are the genetic differences between the Swinhoe´s Rails from Russia & Aomori compared to those from other Japanese sites. The present study had no taxonomic focus, but at least we can not exclude the possibility that Swinhoe´s Rail might consist of several taxonomic units.
Given all those uncertainties, I would prefer to keep the discussion open and/or leave its Red List category unchanged.