World distribution map
Swifts mature and breed when they are four years old. Those that survive the hazardous early years can expect to survive a further 4-6 years. The oldest ringed bird lived for at least 21 years. Because of their mastery of the air, swifts have few predators. Tired, hungry birds are sometimes taken by birds of prey such as hobbies.
Pair bonds are often formed when the birds are only one year old. These birds sometimes occupy a nest hole and may even attempt to build a nest. However, they are unlikely to nest successfully until they are four years old.
Swifts pair for life, meeting up each spring at the same nest site.
Swifts normally lay two or three eggs at two or three day intervals. Incubation starts with the first egg, and lasts for 19–20 days per egg. The adults share all the nesting duties equally. Fertile and infertile eggs are not uncommonly ejected from the nest at any time. The reason for this behaviour remains unclear.
The nest is located high up in the roof space under the eaves of old houses and churches where the birds are able to drop into the air from the nest entrance. The nest is built by both adults out of any material that can be gathered on the wing, including feathers, paper, straw, hay and seeds. It is cemented together with saliva, and renovated and reused year after year.
Swift Breeding and Nesting Habits - The RSPB
Video introduction
Video introduction
In the early part of the last century, the population of Beijing Swift had reached its peak, about 50,000. However, with the development of Beijing's urbanization, in 2014, the survey data on the number of Swiftlets in Beijing provided by the Beijing Bird Watching Society showed that there were only about 3,000 Swiftlets in Beijing.
Brain Size and Life History Interact to Predict Urban Tolerance in Birds