Data Zone
Justification of Red List category
This species qualifies as Vulnerable due to a small population size, as a result of a very large one-off population reduction caused by the 2004 tsunami. Monitoring in the years after the tsunami suggests that the population is stable, although there is increased pressure on littoral forests and it is now more than a decade since the last survey. Evidence of declines in the population would lead to a category change in the future.
Population justification
Prior to the 2003 tsunami, a survey in 1994 estimated that the population totalled 2,322–4,065 pairs, rounded to 4,500-8,000 mature individuals (Sankaran 1995). This was based on an average of 2.0-3.5 pairs per mound using an estimated total of 1,161 active mounds extrapolated from transects placed in coastal areas. Mounds further than 100 m from the shore were excluded, and no inland areas were surveyed. The species does however create mounds in inland areas, and there may be a significant number of additional breeding pairs especially on Great Nicobar Island.
The 2004 tsunami dramatically reduced the population. Sivakumar (2010) estimated 394 active mounds in 2006 based on the same methodology as Sankaran (1995). Using the mean minimum of 2 pairs using a mound, 788 breeding pairs, the population had been reduced by 66%. But post-tsunami the mounds themselves were smaller, suggesting that the overall reduction may have been even greater, up to 81% if comparing 3.5 pairs per mound before the tsumani and 2 pairs per mound afterwards. Sivakumar estimated that the bounds of the population should be set by using just one pair per mound as the minimum and two as the maximum, giving an estimate of 788-1,566 mature individuals. A follow-up between 2009-2011 (A. P. Zaibin in litt. 2012) estimated a similar number, 376-788 pairs, again suggesting a population that can be rounded to 750-1,500 mature individuals. This suggests that the population was likely stable for the few years after the tsunami, and while it is suspected that the habitat will return to a more favourable state and allow recovery over time an updated estimate is now needed.
The impact of the tsunami was similar across both subspecies, with an estimated reduction in the number of active mounds of 69% for M. n. nicobariensis and 65% for M. n. abbotti. subspecies, with the nominate (north of the Sombrero channel) estimated to number 97–194 breeding pairs (194-388 mature individuals) and M. n. abbotti 297–594 breeding pairs (594-1088 mature individuals) (Sivakumar 2010).
An important caveat is that none of the surveys have accounted for the proportion breeding in inland areas. While these may be at much lower density, they are also unlikely to have been impacted as severely by the tsunami and may be expected to mildly buffer the severity of the population reduction. Overall, the 2003 tsunami is inferred to have caused a population reduction of between 66% and 75%, with the best value considered 66%. While it is not an event that is expected to recur, and the reduction can be viewed as reversible, this single incident increased the species risk of extinction through a significant one-off population reduction from which the species requires secure habitat and a time to recover.
Trend justification
Although survey results from 2006, following the 2004 tsunami, suggest that its numbers had declined by 66-75% on the 1994 population estimate (Sivakumar 2007, 2010), preliminary reports suggested that a natural recovery was underway (R. Sankaran in litt. 2008), despite the worsening of some threats (Sivakumar 2010), and surveys carried out in 2009-2011 suggest that the population has remained stable (A. P. Zaibin in litt. 2012).
Megapodius nicobariensis is endemic to the Nicobar Islands, India (BirdLife International 2001), where it occurs as two races: M. n. abbotti on Great Nicobar, Little Nicobar, Kondul, Menchal, Treis, Meroe, and M. n. nicobariensis on Camorta, Trinkat, Nancowry, Katchall, Teressa, Bompoka and Tillanchong islands (Sivakumar 2007), with the apparent sighting of a pair on Cubra Island in May 2009, and records from Pilo Milo in May 2011 (A. P. Zaibin in litt. 2012). It was thought to be extinct on Pilo Milo (Sivakumar 2010). Historical reports from Little Andaman, India, and the Cocos Islands, Myanmar, lack substantiating evidence. In 1994, there were estimated to be 2,318-4,056 breeding pairs, but following the tsunami in December 2004 populations disappeared completely from two small islands, Trax and Megapode Island, and the total number of breeding pairs was estimated at 395-790 following surveys in 2006, with the majority on Great Nicobar (203-406) and Little Nicobar (82-164) (Sivakumar 2010). Preliminary assessments since 2006 indicate that although a major interruption to breeding occurred in 2005 and 2006, breeding success had improved (R. Sankaran in litt. 2008); however, some threats, such as the encroachment of plantations, appear to have worsened since the tsunami (Sivakumar 2010). Surveys conducted in 2009-2011 resulted in a population estimate of 376-752 breeding pairs, suggesting that the population has at best remained stable since 2006 (A. P. Zaibin in litt. 2012).
It inhabits forests and secondary growth, with the greatest concentrations in coastal forests. It incubates its eggs in nest-mounds close to the shore which are built from sand, loam and humus. The species is primarily monogamous, although extra-pair copulations have been observed. In a pair, both the male and female contribute to the mound maintenance. Unpaired mature males build and defend mounds to attract a partner (K. Sivakumar in litt. 2004). Several pairs often share nest-mounds, with a strong hierarchy apparent during egg-laying. Larger mounds tend to have more stable incubation temperatures and the shortest incubation period (c.72 days). Annual hatching success fluctuates widely (e.g. 87% in 1996 cf. 37% in 1997).
The devastating tsunami of 26th December 2004 is estimated to have reduced the population by 66% (per Sankaran 1995 & Sivakumar 2010). Megapode Island was completely submerged by the tsunami and all coastal areas on Trax Island were inundated: the species has not been found there since (Sivakumar 2010). The aftermath of the tsunami has exacerbated the existing pressures on the species and its habitat, with displaced people raising plantation crops to generate revenue and building houses in littoral forests (Sivakumar 2007, 2010). Surveys in 2006 found that, following the tsunami, the distribution of nest-mounds had shifted closer to shores, potentially increasing the risk posed by abnormally high tides and perhaps negatively affecting incubation temperature (Sivakumar 2010).
Nicobar Scrubfowl is also the species identified among the megapodes as being at the greatest risk from climate change (Radley et al. 2018): clearly sea-level rise is of significant future concern and is expected to lead to a reduction in suitable nesting habitat in the future, as well as exacerbating extreme events such as tsunami.
The identified ongoing threat to the species is the loss of coastal forest through conversion to agriculture (coconut, banana and cashew plantations and rice-paddy cultivation), road development projects, which threaten to fragment habitat blocks, particularly on Great Nicobar, and settlement expansion. Habitat has also been lost to the development of airstrips and defence installations (A. Rahmani in litt. 2012). Including damage from the tsunami, 5.5% of forest cover has been lost between 2000-2019 (Global Forest Watch 2021). The proposal to develop Great Nicobar as a free-trade port, including a dry dock and re-fueling terminal at the mouth of the Galathea river (A. Rahmani in litt. 2012), would impact an important nesting ground. This plan has recently been re-announced (The Times of India 2020) with a 4-5 year timeframe.
Snaring and shooting for food, and egg-collecting are localised problems, but are also likely to have increased in frequency following the 2004 tsunami (Sivakumar 2010). Hunting by visitors from the mainland has decreased due to strict law enforcement; however, the increasing ownership of air guns amongst the indigenous populations has exacerbated this threat (A. Rahmani in litt. 2012). The species is likely to be impacted by sand mining in coastal areas, as driven by the demand for cement for construction, and which is difficult to control resulting in some illicit collection (Islam and Rahmani 2010). However, in comparsion to other megapodes, egg-collection is a very minor threat (Sivakumar 2010). Invasive species, particularly feral cats and dogs are a potential threat (K. Sivakumar in litt. 2004). The provision of domestic fowl by the government could bring the threat of avian cholera and other diseases (A. Rahmani in litt. 2012), however domestic chickens have been present within the range of the species for a long time and no disease outbreaks have been recorded in the species.
Conservation Actions Underway
It is listed in Schedule I of the Wildlife Protection Act (1972). It occurs in Campbell Bay and Galathea National Parks on Great Nicobar (a Biosphere Reserve), and three wildlife reserves on uninhabited islands. Designation of most of the Nicobars as tribal areas legally prohibits commercial exploitation of natural resources and settlement or ownership of land by non-tribal peoples. Detailed status surveys and ecological studies are on-going (K. Sivakumar in litt. 2005). Permanent monitoring plots have been established to determine population trends (Sivakumar 2007). Surveys of this species, and other taxa, were conducted between January 2009 and August 2011 as part of the project 'Monitoring post-tsunami coastal ecosystem recovery in the Nicobar Islands' (A. P. Zaibin in litt. 2012). The species is one of 15 threatened species prioritised by the Government of India for the preparation of a ‘Species Recovery Plan’ under its ‘Integrated Development of Wildlife Habitats’ programme (K. Sivakumar in litt. 2012).
43 cm. Large, rufous-brown megapode with short crest. Adult has bare, reddish facial skin, lacking in juvenile. Greenish-brown to red legs and feet. Similar spp. None within range. Possibly confusable, if seen poorly, with mainly terrestrial Nicobar Pigeon Caloenas nicobarica, which has darker, metallic plumage and short, white tail. Philippine Scrubfowl M. cumingii (extralimital) is similar in appearance but darker, and greyer below. Voice Male gives loud territorial calls, rising in pitch and grading into a staccato series. Feeding birds give noisy, cackling contact calls. Hints Partly nocturnal, found solitary or in pairs.
Text account compilers
Martin, R.
Contributors
Dekker, R., Rahmani, A., Sankaran, R., Sivakumar, K. & Zaibin, A.
Recommended citation
BirdLife International (2024) Species factsheet: Nicobar Scrubfowl Megapodius nicobariensis. Downloaded from
https://datazone.birdlife.org/species/factsheet/nicobar-scrubfowl-megapodius-nicobariensis on 22/11/2024.
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 22/11/2024.