Wong Weng Fai’s excellent video clip of the Grey-rumped Treeswift (Hemiprocne longipennis) provides clear proof of cooperative breeding. According to Erritzoe et al. (2007), this is where “more than two individuals provide care to a single brood of offspring.” The extra help comes from non-breeding birds who are siblings from the last brood. These helpers assist in territorial defence, nest building and the rearing of the nestlings.
In the video clip below, it is noted that the female gave way to the male who then moved sideways to the nest to incubate the egg, see also HERE. He then proceeded to peck on the nest rim, probably, as reported in the Whiskered Treeswift (Hemiprocne comata) by Chantler (1999), to add saliva and feathers. The male Grey-rumped Treeswift then looked around and another male suddenly flew in (see screen grab above, egg arrowed). The second male then took over the incubation of the egg.
Among the family of treeswifts (Hemiprocnidae) there is no record of cooperative breeding (Wells, 1999). However, such breeding has been known in Chimney Swift (Chaetura pelagica) (Family Apodidae) (Chantler, 1999).
According to Dr David Wells, “Quite a discovery (!) although these birds can be pretty gregarious – at times up to 50+ foraging out of the same tree crown. I had always assumed that that was a non-breeding season activity, but maybe think again. Not birds that it would ever be easy to mark, unfortunately.”
And Morten Strange added: “…I remember some years back seeing an astonishing flock come out of the rainforest at the Singapore Botanical Gardens. I was standing on the exercise ground when a sparrowhawk flew overhead and spooked them into the air. There might have been as many as 50 although I couldn’t really count them and they quickly settled back into the canopy again. Now it seems that the species is also social during breeding, although this video might be the first actual proof showing two males tending to the same nest.”
Note: Jeremiah Loei played behind-the-scene role in the posting of the above and Wang Luan Keng provided answers to certain queries.
1. Chantler, P., 1999. Family Apodidae (Swifts). In del Hoyo, J., A. Elliott & J. Sargatal (eds.), Handbook of the birds of the world. Vol. 5. Barn-owls to hummingbirds. Lynx Editions, Barcelona. Pp.388-457
2. Erritzoe, J., K. Kampp, K. Winker & C. B. Frith, 2007. The ornithologist’s dictionary. Lynx Edicions, Barcelona. 290 pp.
3. Wells, D. R., 1999. Family Hemiprocnidae (Tree-swifts). In del Hoyo, J., A. Elliott & J. Sargatal (eds.), Handbook of the birds of the world. Vol. 5. Barn-owls to hummingbirds. Lynx Editions, Barcelona. Pp. 458-466.