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 trend is not known, but the population is not believed to be decreasing sufficiently rapidly to approach the thresholds under the population trend criterion (>30% decline over ten years or three generations). The population size has not been quantified, 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). For these reasons the species is evaluated as Least Concern.
The global population size has not been quantified, though in Europe, the breeding population is estimated to number 100-200 pairs, which equates to 200-400 mature individuals (BirdLife International 2015), with Europe forming <5% of the global range. National population sizes have been estimated at possibly c.10,000-100,000 breeding pairs in China and < c.100 breeding pairs in Taiwan (Brazil 2009).
The overall population trend is unclear. Numbers have increased with the introduction of fish-stocking and fish-farming in several areas however decreases in populations have been reported from parts of Syria, Israel, Egypt and Zimbabwe. The species has been impacted by the use of poisons to kill fish and Red-billed Queleas (Quelea quelea) (Woodall 2016). The European population is estimated to be decreasing by at least 10% in 13.2 years (three generations) (BirdLife International 2015).
This species inhabits small and large lakes, large rivers, estuaries, coastal lagoons and sandy and rocky coasts, dams and reservoirs with either fresh or brackish water. It is also found by streams and smaller fast-flowing rivers and marshes. It requires waterside perches such as trees, reeds, fences, posts, huts and other man-made objects for hunting. Breeding season varies across the range but for example in Turkey it lays from August to September (Woodall 2016). It breeds in pairs or in family groups consisting of primary helpers and/or secondary helpers. It can be colonial or solitary. The species nests in earth banks over or up to 1 km from water or occasionally in flat grassy ground. Tunnels are excavated by jabbing at the soil with the bill partially open and kicking soil backwards with the legs. Short holes are dug but the nest-tunnel is typically 1-2.5 m long with an unlined chamber at the end. Clutch size can range from one to seven eggs but usually four or five. Its diet is primarily fish possibly supplemented by aquatic insects, and frogs, tadpoles and molluscs have also been recorded. It hunts from perches, diving into the water to catch prey. Small fish may be swallowed on the wing but larger ones are taken back to the perch and bashed repeatedly. It also regularly hovers before plunging down to take prey in water. The species is generally sedentary with some local movement in response to changes in food availability. However movements can extend over several hundred kilometres (Woodall 2016).
The construction of dams such as the Il?su dam project in Turkey poses a risk to the nesting habitat of this species (Biricik and Karakas 2012). They are also at risk of poisoning through bioaccumulation of pollution and toxins in the fish they prey on (Rayner et al. 1991). In Botswana the species survived the spraying of endosulphan to control tsetse flies (Glossina), but elsewhere it has been badly affected by the use of poisons to kill fish and Red-billed Queleas (Quelea quelea). The use of pesticides in sugar-growing areas of south-east Zimbabwe may have led to its widespread decline (Woodall 2016).
Conservation Actions Underway
Bern Convention Appendix II. Listed as Critically Endangered on Turkish Red List (Kiziroglu 2008). There are no known conservation measures specifically targeting this species.
Conservation Actions Proposed
Research should be developed into the species's range, ecology, habitat requirements and movements to inform future conservation measures. Also, the investigation of potential threats and their impacts is important, particularly looking at pollutants and toxins in the species. In Europe legal protection of the species and key sites should be developed and implemented as well as a Regional Action Plan for the species.
Text account compilers
Ashpole, J, Butchart, S., Ekstrom, J.
BirdLife International (2020) Species factsheet: Ceryle rudis. Downloaded from http://www.birdlife.org on 22/10/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 22/10/2020.