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). 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). The population size is extremely large, and hence does not 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.
In Europe, the breeding population is estimated to number 11,200,000-23,600,000 pairs, which equates to 22,400,000-47,200,000 mature individuals (BirdLife International 2015). Therefore, its global population is likely to fall in the band 10,000,000-500,000,000 mature individuals.
The population is suspected to be decreasing, with local and regional fluctuations recorded (del Hoyo et al. 2004). In Europe, trends between 1980 and 2013 show that populations have undergone a moderate decline (EBCC 2015).
This species occupies open areas, coastal cliffs, cultivation, and human habitations, including towns and cities. In north-west and central Europe, egg-laying occurs from May and in northern and north-east Europe from the end of May. In southern Spain and north Africa laying occurs from March to May and in June-July on the north Indian Subcontinent. The nest is built by both sexes and is enclosed with a small entrance hole near the top. It is made of mud pellets, lined with vegetable fibres and feathers and is attached to the outside of a building or, less often, a bridge, usually under an overhang and sometimes inside buildings. It will also occasionally use a natural sea cliff or rock face and rarely a cave or tree (Turner 2004). Clutches are normally three to five eggs. It feeds almost entirely on flying insects, almost always taken by aerial-pursuit (Snow and Perrins 1998). The species is migratory, with European birds wintering south of the Sahara (Turner 2004).
The species is affected by adverse weather which can have significant impacts during breeding and migration. It is also thought to compete for nest sites with House Sparrows (Passer domesticus) and a study conducted in Poland attributed recent changes in breeding sites to this (Turner 2004).
Conservation Actions Underway
Bern Convention Appendix II. The species has benefited from building developments which provide additional nesting sites. Reductions in air pollution resulting in increased numbers of insects in cities have also lead to an increase in population numbers in some cities (Turner 2004). The Clean Air Act in the U.K. saw increases of this species in London, Birmingham and Manchester, and in Berlin (Germany) there was a 36% increase between 1979 and 1983-1984 (Hagemeijer and Blair 1997).
Conservation Actions Proposed
It is known to readily use specially designed nestboxes (Turner 2004). Although the species is not threatened, populations should be monitored to detect changes in numbers. Continued reductions in air pollution are likely to benefit the species.
Text account compilers
Ashpole, J, Butchart, S., Ekstrom, J. & Khwaja, N.
BirdLife International (2018) Species factsheet: Delichon urbicum. Downloaded from http://www.birdlife.org on 25/06/2018. Recommended citation for factsheets for more than one species: BirdLife International (2018) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 25/06/2018.