BirdLife species factsheet for Red-crowned Crane
This discussion was first published as part of the 2020 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 2021 Red List update this post remains open and the date of posting has been updated.
Red-crowned Crane is a rare species with a continental range in northeast China and southeast Russia (wintering in coastal China and the Korean Peninsula), and an island range in northern Japan (Momose and Momose, 2019). While the continental population includes migratory subpopulations, the island population is resident. The species is both aquatic and terrestrial, preferring grass, reed and sedge marshes for breeding grounds, whilst commonly using wetlands and similar habitats such as tidal flats, rivers and saltmarshes for wintering and passage grounds (Momose and Momose, 2019).
The most significant threat to the Red-crowned Crane remains habitat loss and degradation; hydrological changes, poisoning, illegal hunting and other human-driven factors further threaten the continental population of this species (Momose and Momose, 2019). Due to its dependence on aquatic habitats, the species is additionally highly sensitive to changes in water levels. The island population continues to face issues relating to habituation by humans, leading to traffic accidents and collisions with power lines, as well as infectious diseases in highly concentrated breeding and wintering areas (Momose and Momose, 2019).
The number of mature individuals was previously estimated at 1,830, with a global population of c. 3,050 individuals (J. Harris in litt., 2016). However, the global population is thought to have continued to increase in recent years. Following a census in 2017-2018, the global population is currently estimated at c. 3,430 individuals: 580 in China, 1,250 in Korea and 1,600 in Japan (Momose and Momose, 2019). To account for uncertainty (e.g. the possibility of double counting), the global population is placed in the estimated range of 2,800-3,430 individuals, including c. 2,050 mature individuals (Momose and Momose, 2019). This recent increase in the global population results mainly from the significant population increase in the island population, which outweighs the known declines in some continental populations.
The Red-crowned Crane is currently listed as Endangered under Criterion C1, based on a small population size (<2,500) and >20% decline in 5 years or two generations when last assessed. However, new information about the population size and trend means it may warrant a change in Red List status. Therefore, the species will be re-assessed here against all criteria:
Criterion A: The global population is suggested to have increased from c. 3,050 individuals in 2016 to 3,431 individuals in 2018, which initially does not suggest a population size reduction under IUCN definition (IUCN Standards and Petitions Committee, 2019). However, this change is thought to be a result of significant increases in the island population, possibly masking severe declines in parts of the species’ continental range (Momose and Momose, 2019). Higher numbers reported from parts of the continental range may not reflect a genuine improvement, but rather better counting methods due to increasing concentrations of the species at fewer sites.
Specifically, the Japanese island population has risen from 600 individuals during 1995-1996 to 1,600 in 2017-2018. Similarly, the Korean population remains stable to increasing, whilst numbers have also increased along the Demilitarized Zone (DMZ) between the Democratic People’s Republic of Korea (North Korea) and the Republic of Korea (South Korea) from 500-650 individuals in 1996 to 1,251 in 2017-2018. The species is thought to no longer winter in North Korea, while China (comprising the main range of the continental population) has seen the most significant declines, with only an estimated 580 individuals in 2018, compared to 1,200 individuals in 1999. The Russian range of the population continues to see mixed trends, but is considered overall as stable to increasing (Momose and Momose, 2019).
Since this species was last assessed, an improved estimate of its generation length has been produced, extending it to 15.9 years (Bird et al. 2020)*. For the purposes of this Red List assessment, trends over three generations (47.7 years) are relevant under Criterion A. Notwithstanding the recent overall increase, the global population is still suspected to have declined by >30% since the 1970s (BirdLife International, 2001), which is also supported by the ongoing reductions and range contractions owing to habitat loss and degradation, especially in parts of its continental range (Momose and Momose, 2019). It can therefore be considered to qualify as Vulnerable under Criterion A2c.
Criterion B: The estimated Extent of Occurrence (EOO) is approximately 1,760,000 km2. This is far above the thresholds for a threatened status under this criterion. Therefore, the species meets Least Concern under Criterion B1.
Criterion C: The population size of Red-crowned Crane is thought to number c. 2,050 mature individuals, which is still small. However, as the global population is currently increasing overall, rather than declining, it does not meet the requirements (i.e. continuing decline) for listing under this criterion. Therefore, the species meets Least Concern under Criterion C.
Criterion D: The number of mature individuals (c. 2,050) is more than twice the threshold for a Vulnerable status under Criterion D1. Therefore, the species meets Least Concern under Criterion D.
Criterion E: To the best of our knowledge no quantitative analysis of extinction risk has been conducted for this species. Therefore, it cannot be assessed against this criterion.
Therefore, it is suggested that the Red-crowned Crane (Grus japonensis) be listed as Vulnerable A2c. The available evidence suggests that the species probably qualified for reclassification from Endangered to Vulnerable between 2012 and 2016. We welcome any comments on this proposed listing and on the proposed timing (to inform the coding of genuine changes for the Red List Index).
Please note that this topic is not designed to be a general discussion about the ecology of the species, rather a discussion of its Red List status. Therefore, please make sure your comments are relevant to the discussion outlined in the topic. By submitting a comment, you confirm that you agree to the Comment Policy.
*Bird generation lengths are estimated using the methodology of Bird et al. (2020), as applied to parameter values updated for use in each IUCN Red List for birds reassessment cycle. Values used for the current assessment are available on request. We encourage people to contact us with additional or improved values for the following parameters; adult survival (true survival accounting for dispersal derived from an apparently stable population); mean age at first breeding; and maximum longevity (i.e. the biological maximum, hence values from captive individuals are acceptable).
An information booklet on the Red List Categories and Criteria can be downloaded here and the Red List Criteria Summary Sheet can be downloaded here. Detailed guidance on IUCN Red List terms and definitions and the application of the Red List Categories and Criteria can be downloaded here.
Bird, J. P.; Martin, R.; Akçakaya, H. R.; Gilroy, J.; Burfield, I. J.; Garnett, S.; Symes, A.; Taylor, J.; Šekercioğlu, Ç.; Butchart, S. H. M. 2020. Generation lengths of the world’s birds and their implications for extinction risk. Conservation Biology online first view.
BirdLife International (2001) Threatened birds of Asia: the BirdLife International Red Data Book. Cambridge, UK: BirdLife International.
BirdLife International. (2016). Grus japonensis. The IUCN Red List of Threatened Species 2016.
IUCN Standards and Petitions Committee. 2019. Guidelines for Using the IUCN Red List Categories and Criteria. Version 14. Prepared by the Standards and Petitions Committee. Downloadable from http://www.iucnredlist.org/documents/RedListGuidelines.pdf
Momose, Y., and Momose, K. 2019. Species review: Red-crowned Crane. In: Mirande, C.M., and Harris, J.T., editors. Crane conservation strategy. Baraboo, Wisconsin: International Crane Foundation. p. 245-260.