This discussion was first published as part of the 2018 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 2019 Red List update this post remains open and the date of posting has been updated.
The enigmatic Kagu (Rhynochetos jubatus) is endemic to New Caledonia (to France), occurring primarily in forest habitats. Its restricted and severely fragmented range means that it has been considered Endangered, although this may now require revision. Population trends had previously been considered to be declining as a result of habitat degradation (e.g. Chartendrault and Barré 2005, 2006), and mortality caused by introduced species such as cats, rats, pigs, and dogs as well as from hunting (Hunt et al. 1996, Y. Létocart in litt. 1999, J. Theuerkauf in litt. 2007, S. Rouys in litt. 2008).
However, for some time now (at least since the 2008 Red List assessment) the population trend has been considered to be stable. Field surveys by Chartendrault and Barré (2005, 2006) confirmed that kagus are still found in most of the areas previously surveyed by Hunt in 1992, and with decreasing hunting activity in many areas, birds are being able to recolonise places they had previously been extirpated from (R. Gula and J. Theuerkauf in litt. 2012). Population surveys in the key areas for this species have shown an increasing population in Parc Grandes Fougères, and a fluctuating population in Parc Provincial Rivière Bleue, though the population at this site may be stable over the long term (J. Theuerkauf in litt. 2016).
Further, the Extent of Occurrence (EOO) of this species has been recalculated using a Minimum Convex Polygon to strictly follow IUCN guidelines (IUCN 2001, 2012, Joppa et al. 2016), and this newly calculated EOO means the species may no longer meet the threshold for Endangered under any Red List Criterion. Therefore, given this information the species has been re-assessed against all criteria using current information.
Criterion A – As the population is currently considered to be stable and there is no quantified evidence of a reduction over the last three generations, it would not warrant listing as threatened under this criterion.
Criterion B – The newly calculated EOO for this species is 7,400km2. This falls in the range for Vulnerable under criterion B1. Analyses from Tracewski et al. (2016) calculated the amount of available forest in 2012 (a proxy for the Area of Occupancy) for this species to be c.1,070km2, which would fall in the range for Vulnerable under criterion B2. The species’ range is considered to be severely fragmented, yet forest loss has been very low (c.0.67% over 3 generations [45 years]; extrapolated from data for 2000-2012) (Tracewski et al. 2016). However, it may be conservative to consider the quality of habitat to be decreasing as introduced deer may damage forests (Chartendrault and Barré 2005, 2006), and pigs may disturb the forest floor (although Ekstrom et al.  suggest that pigs may cause only minimal impacts on Kagu). Therefore, the species may warrant listing as Vulnerable under criteria B1ab(iii)+2ab(iii), although if the currents impacts on habitat quality are deemed minimal it may not warrant listing as threatened under this criterion.
Criterion C – The population in Parc des Grandes Fougères is suspected to be >250 adults, and potentially >1,000 individuals overall (J. Theuerkauf in litt. 2016); 500 individuals are suspected to occur in Parc Provincial Rivière Bleue (J.-M. Mériot in litt. 2007, J. Theuerkauf in litt. 2016); and 491 mature individuals are thought to occur elsewhere in its range. It is uncertain what proportion of the 500 individuals in Parc Provincial Rivière Bleue are mature and so the population size is conservatively considered to be <1,000 mature individuals. This is sufficiently low to meet the threshold for Endangered under this criterion. However, the sub-population structure means it would not meet the sub-population structure conditions for Endangered (meeting those for Vulnerable instead), and the fact that the population is now considered to be stable means that the species would not warrant listing as threatened under criterion C.
Criterion D – The population size estimate of <1,000 mature individuals means that the species meets the threshold for Vulnerable under criterion D1.
Criterion E – No quantitative analysis of extinction risk has been carried out for this species to the best of our knowledge. Therefore, it cannot be assessed against this criterion.
Therefore, it is proposed that Kagu be listed as Vulnerable under criteria B1ab(iii)+2ab(iii); D1. As the population trend has been considered to be stable for at least 5 years then we are unable to use the 5 year rule to pend a downlisting of this species; and even if there were evidence to suggest that the population trend was decreasing overall this would only result in a change in criteria string to Vulnerable under criteria B1ab(iii,v)+2ab(iii,v); C2a(i); D1. Thus to retain the species as Endangered would require evidence of smaller range or sub-population sizes.
Comments on this proposal are welcome, though 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 about the proposed listing.
Chartendrault, V.; Barré, N. 2005. Etude du statut et de la distribution des oiseaux menacés de la Province Nord de Nouvelle-Calédonie. Institut Agronomique néo-Calédonien, New Caledonia.
Chartendrault, V.; Barré, N. 2006. Etude du statut et de la distribution des oiseaux des forêts humides de la province Sud de Nouvelle-Calédonie. Institut agronomique néo-calédonien, Port Laguerre, Nouvelle-Calédonie.
Ekstrom, J. M. M.; Jones, J. P. G.; Willis, J.; Tobias, J.; Dutson, G.; Barré, N. 2002. New information on the distribution, status and conservation of terrestrial bird species in Grande Terre, New Caledonia. Emu 102: 197-207.
Hunt, G. R.; Hay, R.; Veltman, C. J. 1996. Multiple Kagu Rhynochetos jubatus deaths caused by dog attacks at a high-altitude study site on Pic Ningua, New Caledonia. Bird Conservation International 6: 295-306.
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.