• Summary
• Text account
• Data table and detailed info
• Distribution map
• Reference and further resources

Taxonomic note
Rhyticeros narcondami (del Hoyo and Collar 2014) was previously placed in the genus Aceros.

Taxonomic source(s)
del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A. and Fishpool, L.D.C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 1: Non-passerines. Lynx Edicions BirdLife International, Barcelona, Spain and Cambridge, UK.

Red List criteria met

Critically Endangered	Endangered	Vulnerable
-	-	D1+2

Red List history

Year	Category	Criteria
2020	Vulnerable	D1+2
2016	Endangered	D
2012	Endangered	D
2009	Endangered	D1
2008	Vulnerable
2004	Vulnerable
2000	Vulnerable
1996	Vulnerable
1994	Vulnerable
1988	Threatened

Migratory status	not a migrant	Forest dependency	high
Land-mass type		Average mass	-

	Estimate	Data quality
Extent of Occurrence (breeding/resident)	7 km2	medium
Area of Occupancy (breeding/resident)	7 km2	good
Number of locations	1	-
Severely fragmented?	no	-

	Estimate	Data quality	Derivation	Year of estimate
Population size	300-650 mature individuals	good	estimated	2020
Population trend	stable	medium	suspected	-
Rate of change over the future 10 years/3 generations (longer of the two periods)	0%	-	-	-
Generation length	7.2 years	-	-	-
Number of subpopulations	1	-	-	-
Percentage of mature individuals in largest subpopulation	100%	-	-	-

Population justification: The population is estimated to number between 750-1,400 individuals (R. Naniwadekar unpublished data in litt. to the IUCN SSC Hornbill Specialist Group 2020). This is based on the 95% confidence interval from an extrapolation of the density estimates derived during fieldwork between December 2019 and February 2020. To estimate the number of mature individuals, two pieces of additional information are used. A previous study investigating the species estimated that the breeding population was 46-53% of the total number of individuals (Vijayan and Sankaran 2000). Second, a male-biased sex-ratio (56/44) was recorded by Manchi (2017), which would slightly reduce the number of mature individuals to consider in the assessment. Using the most recent estimate, the population size is between 345 – 742 mature individuals when applying the proportion of the breeding population from Vijayan and Sankaran 2000, but further reduced if we account for the skewed sex ratio to 304-653 mature individuals, rounded to 300-650 mature individuals.

The earliest known estimate of Narcondam Hornbill population was by Osmaston (1905) who collected ten hornbill specimens and gave a ‘liberal estimate’ of not more than 200 on the island. Based on an approximately month-long survey in March-April 1972, Hussain (1984, 1993) suggested a higher ‘liberal estimate’ of around 400 birds on the island. The first transect-based estimate, based on a 3-month survey in 1998, reported around 330 – 360 birds on Narcondam (Vijayan and Sankaran 2000). Yahya and Zarri (2002) made a brief survey in March 2000 using two line transect methods and estimated the hornbill density at 72/km² and 83/km², suggesting a total population of 432 or 498 birds over 6 km² of habitat estimated to be available. In 2003, Vivek and Vijayan (2003) found the overall density of the species was estimated at around 54 individuals per km² (Vivek and Vijayan 2003). The population was estimated to number 320-340 individuals, based on an effective area of habitat of 6 km². 

The results of these studies were interpreted by Kinnaird and O'Brien (2007) to equate to fewer than 250 mature individuals, hence the population was placed in the band 50-249 mature individuals. However, since 2010 all studies indicate that the numbers are higher. In a 4-day survey in April 2010, the density of Narcondam Hornbills estimated using variable-width line transect surveys on trails in lowland forest was found to be around 167 birds/km² (95% confidence interval of 63.3–271 individuals/km²) (Raman et al. 2013). Raman et al. 2013 emphasised that the density should not be extrapolated to the island as the trails surveyed were non-randomly placed. Manchi (2017) reported a density of 190 ± 81 birds/km² based on transect surveys with an estimated population of 1295 birds (extrapolated for the whole island). However, most of the population is distributed below 500 m above msl, hence the total population was likely an overestimate.

Trend justification: Its population appears to be stable or increasing following efforts to reduce hunting and habitat degradation, as well as the removal of feral goats and almost all introduced cats (Manchi 2017, R. Naniwadekar in litt. 2020). Although recent (2010 onwards) density estimates are higher than in previous years, as different methods were used, it is difficult to conclude strongly whether there has been an increase in population and number of mature individuals.

Country/Territory	Presence	Origin	Resident	Breeding visitor	Non-breeding visitor	Passage migrant
India	extant	native	yes

Country/Territory	IBA Name
India	Narcondam Island Wildlife Sanctuary

Habitat (level 1)	Habitat (level 2)	Importance	Occurrence
Forest	Subtropical/Tropical Moist Lowland	major	resident
Shrubland	Subtropical/Tropical Moist	major	resident
Altitude	0 - 700 m	Occasional altitudinal limits

Threat (level 1)	Threat (level 2)	Impact and Stresses
Agriculture & aquaculture	Annual & perennial non-timber crops - Small-holder farming	Timing		Scope		Severity		Impact
		Past, Likely to Return		Minority (<50%)		Negligible declines		Past Impact
		Stresses Ecosystem degradation, Ecosystem conversion
Biological resource use	Hunting & trapping terrestrial animals - Intentional use (species is the target)	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Negligible declines		Low Impact: 4
		Stresses Species mortality
Biological resource use	Logging & wood harvesting - Unintentional effects: (subsistence/small scale) [harvest]	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		No decline		Low Impact: 4
		Stresses Ecosystem degradation
Climate change & severe weather	Storms & flooding	Timing		Scope		Severity		Impact
		Past, Likely to Return		Whole (>90%)		Negligible declines		Past Impact
		Stresses Ecosystem degradation, Species mortality
Invasive and other problematic species, genes & diseases	Diseases of unknown cause	Timing		Scope		Severity		Impact
		Future		Majority (50-90%)		Rapid Declines		Low Impact: 5
		Stresses Reduced reproductive success, Species mortality
Invasive and other problematic species, genes & diseases	Invasive non-native/alien species/diseases - Capra hircus	Timing		Scope		Severity		Impact
		Past, Unlikely to Return		Whole (>90%)		Negligible declines		Past Impact
		Stresses Ecosystem degradation
Invasive and other problematic species, genes & diseases	Invasive non-native/alien species/diseases - Felis catus	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		No decline		Low Impact: 4
		Stresses Species mortality
Invasive and other problematic species, genes & diseases	Invasive non-native/alien species/diseases - Unspecified species	Timing		Scope		Severity		Impact
		Past, Unlikely to Return		Minority (<50%)		Negligible declines		Past Impact
		Stresses Ecosystem degradation
Residential & commercial development	Commercial & industrial areas	Timing		Scope		Severity		Impact
		Future		Minority (<50%)		Slow, Significant Declines		Low Impact: 3
		Stresses Species disturbance, Ecosystem degradation, Ecosystem conversion

Purpose	Scale
Food - human	subsistence, national
Pets/display animals, horticulture	international

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Recommended citation
BirdLife International (2024) Species factsheet: Narcondam Hornbill Rhyticeros narcondami. Downloaded from https://datazone.birdlife.org/species/factsheet/narcondam-hornbill-rhyticeros-narcondami on 27/12/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from https://datazone.birdlife.org/species/search on 27/12/2024.