BirdLife species factsheet for Vietnamese Cutia: http://datazone.birdlife.org/species/factsheet/vietnamese-cutia-cutia-legalleni
Vietnamese Cutia (Cutia legalleni) is only known to occur in Laos and Vietnam. The nominate subspecies only occurs on the Da Lat Plateau, southern Vietnam; while subspecies hoae occurs on the Kon Tum Pleateau in eastern Laos and central Vietnam. It occurs at altitudes of 1,200-2,100m, inhabiting evergreen broadleaf forest, as well as mixed broadleaf-pine forest and occasionally pine forest, albeit usually when it is close to broadleaf forest (Collar and Robson 2018). Logging and conversion to coffee plantations is thought to be threatening the species’s habitat, while the species is also being caught and traded as a pet (Le Manh Hung in litt. 2016).
The species has been considered Near Threatened under Criterion B1 (see BirdLife International 2018). However, this is no longer tenable because this was based on an Extent of Occurrence (EOO) value calculated as the ‘area of mapped range’. This is no longer appropriate and the EOO should be calculated using a Minimum Convex Polygon (see IUCN 2001, 2012, Joppa et al. 2016), as EOO is a measure of the spatial spread of areas occupied by a species, not the actual area it occupies. The resulting EOO value now exceeds the thresholds required to maintain the species’s current listing, and as such it potentially cannot retain its current Red List status. Therefore, we have fully reviewed the species here against all criteria.
The initial topic on this analysis can be found here.
Criterion A – The population trend for this species has not been directly estimated. However, deforestation data from between 2000 and 2012 (Tracewski et al. 2016), suggests that the area of suitable habitat for the species on average is declining by c.8.1% over three generations (16.5 years). Therefore, assuming that population declines are proportional to habitat loss would mean that the rate of population decline would not approach the threshold for Vulnerable. Even taking into account that the species could potentially be impacted by capture for trade, without further information, it is still unlikely that the overall rate of decline would approach the threshold for listing as Vulnerable under this criterion. As such, Vietnamese Cutia is assessed as Least Concern under Criterion A.
Criterion B – The newly calculated Extent of Occurrence is 98,300 km2, while Tracewski et al. (2016) estimated the maximum Area of Occupancy (AOO) (calculated as the remaining tree area within the species’s range) to be c.19,626 km2. Both values exceed their relevant thresholds (20,000 km2 and 2,000 km2 respectively), and so the species does not warrant listing under this criterion. As such, Vietnamese Cutia is assessed as Least Concern under Criterion B.
Criterion C – The application of this criterion depends on the population size estimate, but to the best of our knowledge there has been no direct estimation of the population size for this species. Vietnamese Cutia is described as locally common (Collar and Robson 2018) and, looking at density estimates of other species in the family Leiotrichidae, it is unlikely that the population size would approach the threshold for Vulnerable under this criterion (10,000 mature individuals). Therefore, it would not warrant listing under this criterion. However, we do request any information regarding population size estimates, as the lack of information means there is still a chance it could approach this threshold.
Even if Vietnamese Cutia does meet or approach this threshold, it would not warrant listing as more threatened than Near Threatened. The species occurs in >1 subpopulation, with each likely containing >1,000 mature individuals and it is not known to undergo extreme fluctuations (preventing the species from qualifying as threatened under Criteria C2a(ii), C2a(i) and C2b respectively). Having a suspected decline in the region of 10% over three generations does mean that, if the population size approaches or is <10,000 mature individuals, it could be listed as Near Threatened under Criterion C1. However, because this is only a suspected rate of decline rather than a directly estimated/observed population trend, the species cannot qualify as threatened under this criterion.
Criterion D – The species’s range is too large to warrant listing under this criterion, and it is likely that its population size is too large also. Vietnamese Cutia is assessed as Least Concern under Criterion D.
Criterion E – To the best of our knowledge there has been no quantitative analysis of extinction risk conducted for this species. Therefore, it cannot be assessed against this criterion.
Therefore, the species likely warrants listing as Least Concern. However, we do request further information regarding potential population size estimates in case the number of individuals may approach or fall below 10,000 mature individuals. Please note that this topic is not designed to be a general discussion about the ecology of the species, rather a discussion of the species’ Red List status. Therefore, please make sure your comments are relevant to the species’ Red List status and the information requested.
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.
BirdLife International. 2018. Species factsheet: Cutia legalleni. Downloaded from http://www.birdlife.org on 28/09/2018.
Collar, N.; Robson, C. 2018. Vietnamese Cutia (Cutia legalleni). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from https://www.hbw.com/node/59578 on 28 September 2018).
IUCN. 2001. IUCN Red List Categories and Criteria: Version 3.1. IUCN Species Survival Commission. IUCN, Gland, Switzerland and Cambridge, U.K.
IUCN. 2012. IUCN Red List Categories and Criteria: Version 3.1. Second edition. IUCN Species Survival Commission. IUCN, Gland, Switzerland and Cambridge, U.K. Available at: www.iucnredlist.org/technical-documents/categories-and-criteria.
Joppa, L. N.; Butchart, S. H. M.; Hoffmann, M.; Bachman, S. P.; Akçakaya, H. R.; Moat, J. F.; Böhm, M.; Holland, R. A.; Newton, A.; Polidoro, B.; Hughes, A. 2016. Impact of alternative metrics on estimates of extent of occurrence for extinction risk assessment. Conservation Biology 30: 362-370.
Tracewski, Ł.; Butchart, S. H. M.; Di Marco, M.; Ficetola, G. F.; Rondinini, C.; Symes, A.; Wheatley, H.; Beresford, A. E.; Buchanan, G. M. 2016. Toward quantification of the impact of 21st-century deforestation on the extinction risk of terrestrial vertebrates. Conservation Biology 30: 1070-1079.