BirdLife species factsheet for Asian Woollyneck
The Asian Woollyneck is a species of stork that occurs across South Asia and South-East Asia. Its range extends through India (extending to parts of East Pakistan), Bangladesh, Nepal, Bhutan and Sri Lanka, down to western and south-western Myanmar, southern parts of Thailand, Laos and Vietnam, Cambodia, restricted parts of peninsular Malaysia, and across Indonesia (BirdLife International 2017, eBird 2020). Its presence in the Philippines is however presumed to be extirpated, leading to an extremely restricted range here (Gonzalez et al. 2018, eBird 2020). The species also remains rare or near extinction in Bangladesh, Pakistan, Thailand and Vietnam (del Hoyo et al. 2020). However, it remains common and widespread across much of South Asia (including India and Sri Lanka), and has also seen recent records in the Yunnan Province of China (eBird 2020). The Asian Woollyneck prefers well-watered areas, such as floodplains, marshes, paddyfields, ponds and lagoons, while nesting will commonly occur on tall trees or even urban structures such as mobile phone towers (Sundar 2006, Vaghela et al. 2015, del Hoyo et al. 2020).
Ongoing threats include habitat loss and fragmentation, nest destruction, environmental pollution and hunting (Sundar 2006, Jangtarwan et al. 2019, del Hoyo et al. 2020), which may be driving regional declines, especially in parts of South-East Asia. Additionally, the global population was previously estimated at 35,000 mature individuals (BirdLife International 2017; Wetlands International 2020). However, recent estimates suggest the population may actually number 120,000-310,000 individuals (G. Sundar in litt. 2019). Assuming that roughly two-thirds of these are mature individuals, the population of the Asian Woollyneck may tentatively number 80,000-210,000 mature individuals.
The Asian Woollyneck is currently listed as Vulnerable under Criterion A2cd+3cd+4cd, based on a suspected range-wide decline exceeding 30% over three generations, when last assessed. However, information regarding new population estimates and trends may warrant a change in Red List status. Therefore, the species is here re-assessed here against all criteria:
Criterion A – The species was previously suspected to be declining overall at a rate exceeding 30% across a 3-generation period (27.6 years, Bird et al. 2020)*. However, this was based largely on information about threats and local declines in South-East Asia, where the species remains rare. Although it still faces a number of threats and has seen local declines in parts of its range, the currently available evidence suggests that the species continues to remain stable across the larger South Asian range (del Hoyo et al. 2020), and has not declined so rapidly. Further information is however sought to determine the species’s current overall population trend. If the evidence suggests that its global population has declined or is likely to decline at a rate approaching 30% over three generations, then the species may qualify as Near Threatened under Criterion A2cde+3cde+4cde. Otherwise, it will be assessed as Least Concern under Criterion A.
Criterion B – The estimated Extent of Occurrence (EOO) is approximately 18,600,000 km2. This is far beyond the threshold (<20,000 km2) required to qualify for a threatened status. Therefore, the species is Least Concern under Criterion B.
Criterion C – The population of Asian Woollyneck is now thought to number 80,000-210,000 mature individuals (G. Sundar in litt. 2019). This is far beyond the threshold (<10,000 mature individuals) required to qualify for a threatened status. Thus, the species is Least Concern under Criterion C.
Criterion D – The number of mature individuals and range size estimated for this species fall far beyond the thresholds needed for a threatened status under this criterion. Therefore, the Asian Woollyneck qualifies as 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, depending on the overall magnitude of any global population decline, it is suggested that the Asian Woollyneck (Ciconia episcopus) be listed as either Least Concern or Near Threatened, approaching the threshold for listing as threatenedunder Criterion A2cde+3cde+4cde. We welcome any comments on the proposed listing and specifically ask for further information regarding recent population trends. Is there evidence for past, present and/or future declines approaching 30% over three generations (27.6 years)?
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. (2017). Ciconia episcopus (amended version of 2016 assessment). The IUCN Red List of Threatened Species 2017.
del Hoyo, J., Elliott, A., Collar, N., Garcia, E. F. J., Boesman, P. F. D., and Kirwan, G. M. (2020). Woolly-necked Stork (Ciconia episcopus), version 1.0. In Birds of the World (Billerman, S. M., Keeney, B. K., Rodewald, P. G., and Schulenberg, T. S., Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.wonsto1.01
eBird. 2020. eBird: An online database of bird distribution and abundance. Ithaca, NY, USA Available at: http://www.ebird.org.
Gonzalez, J. C. T. et al. (2018). Review and update of the 2004 National List of Threatened Terrestrial Fauna of the Philippines. The Technical Journal of Philippine Ecosystems and Natural Resources; 28 (1), 73-144.
Jangtarwan, K. et al. (2019). Take one step backward to move forward: Assessment of genetic diversity and population structure of captive Asian woolly-necked storks (Ciconia episcopus). PLoS ONE; 14 (10), 1-17.
Sundar, G. (2006). Flock size, density and habitat selection of four large waterbirds species in an agricultural landscape in Uttar Pradesh, India: Implications for management. Waterbirds; 29(3): 365-374.
Sundar, G. (2019). Stork, Ibis and Spoonbill Specialist Group. Personal communication.
Vaghela, U., Sawant, D., and Bhagwat, V. (2015). Woolly-necked Storks Ciconia episcopus nesting on mobile-towers in Pune, Maharashtra. Indian BIRDS; 10 (6), 154-155.
Wetlands International. 2020. Waterbird Population Estimates. Available at: http://wpe.wetlands.org.