Ling Kwee Chang’s two earlier posts on the Grey-rumped Treeswift (Hemiprocne longipennis) HERE and HERE established that incubation takes 21 day and the fledging 32 days. This compares favourably with Adam & Morten Strange’s 20-24 days for incubation and 28 days for fledging.
And Wells (1999) reported: “…combined development time exceeds 50 days (an egg in 7 June, hatched by 3 July with young newly on the wing on 1 Aug.). This works out to an incubation period of 26 days and fledging period of 29 days.
It has also been established that the Grey-rumped Treeswift indulges in cooperative breeding. This involves more than the two adult parents providing care to the developing chicks. These helpers come from non-breeding birds, often siblings from the last brood. They also assist in territorial defence and nest building.
Images are courtesy of Johnny Wee. From top to bottom: female incubating the egg and about to be relieved of her duty by the male; recently fledged chick; and juvenile.