Data Zone
Justification of Red List category
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km² combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population size may be moderately small to large, but it is not believed to approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). For these reasons the species is evaluated as Least Concern.
Population justification
There are 7,000-13,000 individuals in West and Central Africa and 8,000-12,000 in East Africa and South Africa (T. Dodman in litt. 2002 via Wetlands International 2021), giving a total of 15,000-25,000 individuals, roughly equivalent to 10,000-17,000 mature individuals.
Trend justification
The population is suspected to be in decline owing to wetland habitat degradation, over-exploitation and human disturbance.
Rynchops flavirostris is widespread in sub-Saharan Africa, but is largely confined when breeding to large, dry sandbars in broad rivers and some lakes, below 1,800 m (Coppinger et al. 1988). It is less restricted in the non-breeding season, dispersing to rivers, lakes and coasts in countries as widespread as Egypt, Gambia and Botswana. In Botswana, they disappear from breeding areas in the austral summer and autumn (S. Tyler in litt. 2020). Large concentrations (including breeding birds) occur along the Zambezi River (F. Dowsett-Lemaire and R. J. Dowsett in litt. 2000), e.g. 1,428 individuals (Coppinger et al. 1988), and non-breeding flocks of at least 1,000 individuals have been recorded in Tanzania and Kenya. Research by (Gamundani et al., 2017) suggests that breeding in Zimbabwe has not recovered, more than fifty years after the creation of Lake Kariba. The population is estimated to number 15,000-25,000 birds (with 7,000-13,000 in West and Central Africa and 8,000-12,000 in East Africa and South Africa) (T. Dodman 2002 in litt. to Wetlands International 2002), and the species is thought to be declining (Zusi 1996). The species is rarely seen in Mauritania, having been observed only once in the last ten years, at the Diawling National Park in 2017 (F. Diawara in litt. 2021). In Uganda, the species is rare, only being commonly recorded on the Kazinga Channel in Queen Elizabeth National Park. It is rarely seen along the Albert Nile in Murchison Falls National Park, and at Lutembe Bay on Lake Victoria (D. Nalwanga in litt. 2021). The species has also been observed in Sudan (I. M. Hashim in litt. 2021).
Behaviour The species migrates up and down larger rivers, and to and from inland lakes (del Hoyo et al. 1996), dispersing widely after the breeding season (Tyler 2004). Migration is driven by the need for calm weather (Urban et al. 1986). Breeding takes place during the dry season when rivers are at their lowest and sandbars most exposed (del Hoyo et al. 1996). This generally occurs from March to June in West and East Africa, and mainly from July to November south of the equator (del Hoyo et al. 1996). In Nigeria the species disperses up to 600km from its breeding sites in June - August (Urban et al. 1986), moving mainly downstream (Urban et al. 1986). It returns in November or December, coinciding with the onset of strong winds in its non-breeding areas (Urban et al. 1986). Breeding occurs in small colonies of up to 50 pairs (Tyler 2004). In Botswana, it breeds along the Okavango and Chobe rivers between July and November (Tyler, 2012). During the non-breeding season larger flocks are formed, sometimes of up to 1500 birds (Tyler 2004). Habitat This species requires expanses of calm water for feeding (Urban et al. 1986). Breeding It breeds along broad rivers on large, dry sandbars that are largely free from vegetation (Urban et al. 1986). It sometimes breeds on sandy lake shores, and very occasionally on sandy sea shores (Urban et al. 1986). Non-breeding During the non-breeding season it is more commonly found at lakes (Urban et al. 1986) and also frequents coastal lagoons, salt-pans, open marshes and estuaries (Urban et al. 1986, del Hoyo et al. 1996). It is less common along coasts (del Hoyo et al. 1996). Vagrant birds may use swamps and artificial habitats such as sewage ponds and dams (Urban et al. 1986). Diet It feeds on fish, such as cichlids (del Hoyo et al. 1996), foraging exclusively in the fashion characteristic of the family Rynchopidae, namely by skimming the water in flight with its mouth open and lower mandible submerged (del Hoyo et al. 1996). Breeding site Eggs are laid in an unlined scrape in the sand (Urban et al. 1986, del Hoyo et al. 1996). Scrapes occurs within 2-14m of one another (Urban et al. 1986) and are initially created within 30m of the water (Urban et al. 1986), though falling water levels may increase this distance (Urban et al. 1986). The clutch-size is two or three, rarely four, and the incubation period is c.21 days followed by a fledging period of about four weeks (del Hoyo et al. 1996).
Dam-building has flooded some upstream areas and reduced downstream flows, destroying suitable habitat (Urban et al. 1986, Coppinger et al. 1988, Ginn et al. 1989). Farming practices have also caused siltation of many rivers, raising river levels and swamping breeding islands (Urban et al. 1986, Ginn et al. 1989). Egg-collecting, trapping of adults and general disturbance by humans, cattle and recently increased boat traffic can be serious problems in some areas (Britton 1980, Coppinger et al. 1988, Tyler and Stone 2000). Disruption by recreational fishermen may impact breeding colonies in the Okavango Panhandle, and local fishermen have been reported using chicks as bait (Vial 1995; cited in Hancock 2008). Food supplies may have been reduced by pollution, overfishing and introduced predatory fish, but it is unclear whether this has affected its prey of small fry (fish) (Tyler and Stone 2000). Large-scale spraying of DDT and general water pollution may result in toxic bioaccumulation of pollutants in these piscivores (Coppinger et al. 1988). Boat wash, and the hauling out of crocodiles and hippos can cause disturbance on the sandbanks (S. Tyler, in litt. 2020).
Conservation Actions Underway
No actions targeted at this species are known.
36-42cm. Unmistakeable in range, large tern-like bird with lower mandible longer than upper. Strikingly black above and white below. Similar spp. The combination of a pale distal part of bill and continuous black hindneck in breeding plumage separates the species from R. niger and R. albicollis respectively.
Text account compilers
Clark, J.
Contributors
Baker, L., Baker, N., Butchart, S., Claffey, P., Dodman, T., Dowsett, R.J., Dowsett-Lemaire, F., Ekstrom, J., Evans, M., Hall, P., Malpas, L., Martin, R., O'Brien, A., Pilgrim, J., Rommens, W., Taylor, J., Tyler, S. & Westrip, J.R.S.
Recommended citation
BirdLife International (2024) Species factsheet: African Skimmer Rynchops flavirostris. Downloaded from
https://datazone.birdlife.org/species/factsheet/african-skimmer-rynchops-flavirostris on 23/12/2024.
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 23/12/2024.