Data Zone
Justification of Red List category
As a result of decades of population decline, Indian Skimmer is listed as Endangered as it now has a small global population size and is suffering a continuing decline in excess of 20% in 11 years (two generations). Increased variation in water levels along the rivers on which it breeds due to dams, irrigation and sand mining leads to both flooding of colonies and low water levels that allow access to terrestrial predators and people onto breeding islands. Both situations result in high egg and chick mortality, and the rate of reproduction does not appear to be sufficient to maintain the population. Declines have been continuing for many decades in this previously common and distinctive bird. The species has been lost as a breeding bird from all of South East Asia, Myanmar and probably now also Pakistan. The recent and future rate of population reduction is thus estimated at 34-46% over three generations.
Population justification
The population is estimated at 2,450-2,900 mature individuals, based on the compilation of counts and expert estimates from across the species's range (Chowdhury et al. 2020, Shaikh 2020, S.U. Chowdhury, D.K. Das, S. Debata, S. Mohsanin, T. Munkur, P. Shaikh, C Zöckler in litt. 2020). Much of the research into the status of the species was collated during the Riverine birds of the Central Asian Flyway workshop in November 2019.
The revised estimate is based on numbers recorded during the non-breeding season, when a majority of the population occurs in a few large groups at regular sites. The largest numbers recorded in recent decades have been from the Meghna-Padma delta in Bangladesh, where a total of 3,108 individuals were counted at Nijhum Dwip in February 2020 (D.K. Das in litt. 2020). This is the highest count since 2001, when 5,400 individuals were recorded from the same area (Li et al. 2009). This 2020 count is considerably higher than the previous counts conducted in the area in the 2019/20 season (and for many years), it presumably includes birds noted earlier from Chittagong (Chowdhury et al. 2020) plus any wintering birds unseen in the area. As such it is likely to represent a count close to the total number wintering in Bangladesh.
In India, most observations during the non-breeding season are of few birds but larger congregations are known from a handful of key sites. To the far west of the range c. 150 are regularly recorded from Jamnagar in Gujarat (eBird 2020, Shaikh 2020), centrally c. 100-300 remain on the Yamuna and Ganges rivers (Shaikh 2020), while on the east coast between 200 and 400 have been recorded at Satkosia on the River Mahanadi in Odisha (Debata et al. 2019, S. Debata in litt. 2020) and around 120 at Coringa Wildlife Sanctuary and Kakinada in Andhra Pradesh (eBird 2020, Wetlands International South Asia 2020). Individuals or very small numbers may occur almost anywhere around the coast (for example, recorded in 2018 at Kanyakumari, the southernmost tip of mainland India [S. Balachandran in litt. 2020]) and wander widely in central India during the non-breeding season (eBird 2020).
The population in Pakistan is now thought to be very small: 15 birds were found in surveys of Badin province in 2018 (Ali et al. 2018), close to and possibly connected with those wintering in Gujarat. One bird was observed in the Gulf of Mottama, Myanmar in 2018 (Chowdhury et al. 2020), but it does not seem likely that there is still a regular wintering population in Myanmar. The last regular known wintering group, near Sittwe, numbered 27 in 2008 fell to 9 in 2012, and none have been recorded since (C. Zöckler in litt. 2020).
On the basis of these numbers at wintering sites, the total population in 2020 is estimated at between 3,700 and 4,400 individuals, roughly equating to 2,450-2,900 mature individuals.
Present breeding records are from National Chambal Sanctuary, around 500 adults (Shaikh and Mendis 2019, Singh and Sharma 2018), River Mahanadi, 188-224 adults (Debata et al. 2019), Son Gharial Sanctuary, 50 adults (P. Shaikh in litt 2019), River Ganga, 450 adults (A. Kumar. in litt 2019) and Turtle Wildlife Sanctuary, 13 adults (five pairs) (Mital et al. 2019). Four pairs bred at Pong Dam in 2006, but no nesting has occurred there recently (Fernandes and Besten 2013, S. Balachandran in litt. 2020). The only other confirmed nesting in recent years has been in Bangladesh, where 45 individuals were observed at Chapai Nawabganj, Rajshahi division on 24 April 2016 and three nests subsequently located on 23 May 2016 (Kabir et al. 2016).
A small number may still breed in Pakistan, but there are no recent breeding records in the upper Indus plains and just two recent records of spring birds seem likely to have involved birds on passage, possibly to breeding sites in India (Z.A. Shaikh in litt. 2020).
As such the known breeding population is 1,204-1,280 mature individuals, lower than wintering numbers. This suggests there are additional breeding colonies to locate, and perhaps that a proportion of the mature population are not breeding in any particular year. When it is thought that the number of breeding individuals is reasonably well-known, such a discrepancy in breeding and wintering estimates can be a cause of concern, as it may indicate a severe restriction on breeding sites and hence a lower effective population size.
There are no confirmed records of breeding in Myanmar for over 80 years (C Zöckler in litt. 2020), but loss of the species from the country is likely to have occurred more recently. In south-east Asia the species has not been recorded many decades: in Lao PDR the last documented records are from 1929 (BirdLife 2001). In Cambodia the last record was made between 1950 and 1964, likely in 1960 or 1961 (Thomas and Poole 2003) when 6 birds were observed in Phnom Penh, at the confluence of the Tonle Sap, Mekong and Bassac Rivers (Thomas 1964, BirdLife International 2001). The last Viet Nam records are also from the 19th century (BirdLife International 2001).
Trend justification
The 2020 population estimate, 2,450-2,900 mature individuals, represents an estimated decline of 41% (33.9-45.9%) over three generations (16 years) from the 2001 population estimate of 4,000-6,000 mature individuals (Li et al. 2004, S. Balachandran in litt. 2005).
The species population was previously estimated as 10,000 individuals by Perennou et al.(1994), but it was thought likely to have fallen below this level given the evidence of declines throughout its range (BirdLife International 2001). On the basis of the 2001 Asian Waterbird Census count of 5,542 individuals (Li et al. 2004) and an estimate of the Indian population of 2,500 individuals (S. Balachandran in litt. 2005, noting that some individuals may have been included in both of these counts), a range of 6,000-10,000 individuals roughly equating to 4,000-6,700 mature individuals is taken as the best population estimate for the year 2001.
The rapid population reduction is supported by continuing range contractions. Formerly Indian Skimmer was common along the Indus, but had declined markedly during the twentieth century to the point where during the 1990s in Dera Ismail Khan district, only six records were made, of small groups pre- and post-breeding (Kylänpää 2000). In the past few years there have been only two records in northern Pakistan (Z.A. Shaikh in litt. 2020), a single bird and a pair, both of which moved on quickly. In the 1990s it was concluded that there were likely to still be a handful of breeding pairs in the northern Indus plains, the species is now no more than a rare transitory migrant with only historic breeding records (Z.A. Shaikh in litt. 2020). There continue to be occasional records in the breeding season along the Ayeyarwady River (C. Zockler in litt. 2020, Robson 2020), but it is now believed extinct as a breeding species in Myanmar (C Zöckler in litt. 2020). Similarly it has become a very rare visitor in Nepal, when two decades ago it had declined greatly but still occurred most years (BirdLife International 2001). Now, it is very rare with only a few recent records and is considered regionally Critically Endangered in Nepal (Inskipp et al. 2016). And Indian Skimmers are only very rare visitors to the north east Indian states with only 2-3 records in the past three decades (A. Choudhury in litt. 2020).
Asian Waterbird Census five-year counts in Bangladesh have declined steadily, with maximum counts of 5,400 in 2001–2005, 3,200 in 2005–2010, and 1,343 in 2011–2015 (Li et al. 2009, Mundkur et al. 2017, Chowdhury et al. 2020), but suffer from the likelihood of flocks being missed during a short survey period, as evidenced by the recent large count from Nijhum Dwip (D.K. Das in litt. 2020).
The declines appear to be driven by very low nesting success due to disturbance, predation (especially by feral dogs but also egg collecting by people) and hydrological changes due to dams and abstraction along breeding rivers (Debata et al. 2019, Shaikh et al. 2018, Shaikh and Mendis 2019, Shaikh 2020). As a result, the rate of population reduction appears steady, and is not predicted to either increase or decrease in the future unless there are significant interventions, negative or positive, on the breeding grounds.
Indian Skimmer Rynchops albicollis is now almost completely restricted to India as a breeding bird, with only occasional breeding in western Bangladesh (Kabir et al. 2016). The recent population decline has been accompanied by a range contraction and there are no recent confirmed breeding records from Pakistan or Myanmar.
It was formerly widely distributed across the Indian Subcontinent, along the major rivers of Myanmar and along the Mekong in Indo-China. It was common in the 19th century in Myanmar, Lao PDR, Cambodia and Viet Nam, but there are very few recent records from Myanmar and none from Lao PDR, Cambodia or Viet Nam, where the species is considered to be extinct. In Pakistan it was already rare by the 1990s (Roberts 1991) but in recent years there have been very few records; brief spring migrants in the northern Indus floodplain (Z. A. Shaikh in litt. 2020). In Myanmar there are only very few records of single birds in recent years along the Ayeyarwady River and it is decades since confirmed breeding records (Chowdhury et al. 2020, C. Zöckler in litt. 2020).
A large proportion of the global population winters in the Padma-Meghna delta in Bangladesh (Mohsanin et al. 2014, Chowdhury et al. 2020, S. Mohsanin in litt. 2020, D. K. Das in litt. 2020). Almost all of the remainder remain in India, either along major rivers and reservoirs or at the coast, particularly Gujarat (eBird 2020). Individuals have been recorded wandering as far as the very southern tip of India at Kanyakumari (S. Balachandran in litt. 2020). A very few may also still winter in Myanmar as occasional single individuals have been seen in the Gulf of Mottama (Chowdhury et al. 2020, eBird 2020). However a group near Sittwe numbering 27 in 2008 (Zöckler et al. 2014) have not been observed since 2012 (C. Zöckler in litt. 2020). To the west of the range a few still winter in Pakistan, close to the border with Gujarat in Badin district (Ali et al. 2018). It is now a very rare non-breeding visitor to Nepal (Inskipp et al. 2016), and indeed even to the north-eastern states of India (A. Choudhury in litt. 2020).
In India the species remains widely distributed, but breeding areas are now highly restricted. Most colonies now occur along the Rivers Chambal, Ganges, Yamuna, Mahanadi and Son (eBird 2020, Debata et al. 2019, Dilawar and Shama 2016, Mital et al. 2019, Rajguru 2017, Shaikh et al. 2018, Shaikh and Mendis 2019, T. K. Roy in litt. 2020), with additional breeding records from Pong Dam in Himachal Pradesh (Fernandes and Besten 2013) and the Tawa Reservoir in Madhya Pradesh. A number of other rivers may be suitable for breeding, namely the rivers Godavari, Krishna, Sutlej and Beas, but there are no records despite the recent increase in citizen science data (Shaikh 2020).
The full list of Indian states with recent records of the species based on data from eBird (2020) and Wetlands International South Asia (2020) is as follows; Himachal Pradesh, Punjab, Delhi, Rajasthan, Madhya Pradesh, Uttar Pradesh, Uttarakhand, Bihar, West Bengal, Odisha, Gujarat, Maharashtra, Goa, Karnataka, Andhra Pradesh, Telangana and Tamil Nadu.
It occurs primarily on larger, sandy, lowland rivers, around lakes and adjacent marshes and, in the non-breeding season, estuaries and coasts. It breeds colonially on large, exposed sand-bars and islands, requiring water levels to drop sufficiently to expose the islands and not threaten flooding the nest but not to drop so far as to allow land-based predators access to the colonies (Debata et al. 2019, Shaikh et al. 2019, Shaikh 2020).
Birds return to colonies from February onwards, dependent on water levels. In Odisha, the peak egg-laying period is in April, median clutch size is three (between one and five) and the mean incubation period is 22 days (Debata et al. 2019). Birds had departed the colony by August (Debata et al. 2019).
Nesting success is currently very low. In the National Chambal Sanctuary only 43% of eggs survived to hatching and 35% of chicks then survived to fledging, due to very high rates of egg and chick mortality (Shaikh 2020). In Odisha 61% of nests produced chicks, with only 31% of these chicks surviving to fledging (Debata et al. 2019).
A large proportion of the global population appears to move to coastal areas after breeding, with the largest numbers observed as they gather prior to returning upriver. The remaining individuals may remain on breeding rivers or within the connected river network nearby, or may wander widely in the non-breeding season. Resightings of marked individuals from Chambal have been made on the coast in Gujarat, along the Ganges at Prayagraj (Uttar Pradesh) and at Kakinada, (Andhra Pradesh), suggesting that movements to non-breeding areas of over 1,000 km are not atypical (Shaikh 2020). The critical factor is water level, as the species requires extensive shallows to forage successfully. High water levels will see birds travel large distances to find suitable feeding areas: a pair has been recorded at the southernmost point of mainland India (S. Balachandran in litt. 2020) and there is a record of a vagrant from Oman (Oman Bird Records Database 2020).
In winter birds congregate in areas with extensive mudflats and in some areas saltpans, regularly using offshore sandbars and islands to roost.
Its decline is attributable to widespread increases in human disturbance, exploitation and degradation of rivers and lakes through irrigation schemes, transportation, domestic use, and pollution from agricultural and industrial chemicals. A critical factor is the increasing variation in water level within breeding areas due to greater control of, and demand for water resources. As the species is sensitive to both flooding and to terrestrial predators, any change in water regime is negative for the species.
The population stronghold at National Chambal Sanctuary, India has been badly affected by the damming of the Chambal River in upstream and several existing lift irrigation plants throughout the river resulting in dropping water levels. Low water level and flow rates connects the nesting sandbars to bank, resulting in predation by free-ranging dogs, jackals and trampling by cattle (Shaikh et al. 2018; Shaikh & Mendis 2019, Shaikh 2020). Throughout the breeding range low water levels increase the likelihood and severity of disturbance and opportunistic egg and chick harvesting by people (Debata et al. 2019, Kabir et al. 2016, Shaikh 2020). Greater human presence alongside colonies encourages commensal predators, most seriously feral dogs, but also House Crows Corvus splendens, which have been noted to cause almost complete breeding failure of one colony in one season (Siddiqui et al. 2007). The River Ganga is additionally under pressure from human use of the river for religious gatherings, overfishing and pollution from the major cities of north India (A. Kumar. in litt 2019).
Conversely, issues with water supply for irrigation along the River Mahanadi are mediated though closing sluices to raise water levels, causing frequent flooding of active colonies and nest loss (Debata et al. 2019, Rajguru 2017). Frequent stochastic weather events (e.g. sand storms, heavy pre-monsoon showers and tropical cyclones) can destroy breeding colonies (Shaikh et al. 2018, Debata 2019), which becomes a greater concern as the global population declines. The management of the release of excess water from dams is critical to preventing colony loss through flooding.
Sand mining is an emerging threat for breeding colonies and it might have a long-term effect on nesting-island formation, in addition to causing disturbance to colonies (Das 2015, Debata et al. 2019, Shaikh et al. 2018).
Fuel and chemical discharge from motor boats and large vessels used in river transport may impact aquatic fauna through pollution affecting food supplies for nesting birds (Mital et al 2019). Additional disturbance by bird photographers may also pose a threat to certain colonies if they are repeatedly visited (Kabir et al. 2016).
In the non-breeding areas in Bangladesh, land reclamation (including small scale but persistent reclamation for agricultural land), cross dam construction along the Meghna Estuary, oil spill, mangrove plantation and sea level rise were listed as the most serious and irreversible threats to coastal wetlands (Chowdhury et al. 2017).
Conservation Actions Underway
It occurs in National Chambal Sanctuary, India. Bombay Natural History Society along with the Madhya Pradesh Forest Department has initiated a community-based conservation project at Chambal, engaging local people to act as guardians for key nesting colonies of skimmers and other threatened riverine birds. Under the Biodiversity Conservation and Ganga Rejuvenation of National Mission for Clean Ganga of Government of India, the bird is recognised as a priority species for conservation. The Odisha State Forest Department is working for the conservation of threatened riverine birds including the Indian Skimmer. Nijhum Dwip Marine Reserve declared by the Government of Bangladesh in 2019 is a regular Indian Skimmer non-breeding site. Active management has reduced key threats at some wetland sites.
40-43 cm. Typical skimmer. Black above. White forehead and collar and white below. Long, thick, deep orange bill with yellow tip and longer lower mandible. In flight, white trailing-edge to wing and short forked tail with blackish central feathers. Non-breeders are duller and browner above. Juvenile has dusky orange bill with blackish tip, paler, brownish-grey crown and nape with dark mottling and paler, more brownish-grey mantle, and whitish to pale buff fringing scapulars and wing-coverts. Voice Nasal kap or kip notes, particularly in flight and when disturbed.
Text account compilers
Martin, R., Taylor, J., Westrip, J.R.S.
Contributors
Ali, M., Aung, T., Balachandran, S., Baral, H.S., Bhusal, K., Chaudhary, R., Choudhury, A., Chowdhury, S.U., Das, D.K., Debata, S., Haque, E.U., Inskipp, T., Kar, T., Kumar, A., Mohsanin, S., Mundkur, T., Naing, T., Praveen, J., Quader, S., Rajguru, S., Roy, T.K., Shaikh, P. A., Shaikh, Z. & Zöckler, S.
Recommended citation
BirdLife International (2024) Species factsheet: Indian Skimmer Rynchops albicollis. Downloaded from
https://datazone.birdlife.org/species/factsheet/indian-skimmer-rynchops-albicollis 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.