Although related to the true swifts, these well-dressed, long-tailed birds are in a different family, the Hemiprocnidae which comprises four species. They have very long scissor-like wings and deeply forked tail. The Moustached Treeswift is the largest of the four. It is the only treeswift that occurs in New Guinea. This is the nominate race found on the main island. It is generally darker above and paler below than other subspecies. A faint brownish tinge on the ear coverts suggests this is a male. Canon PowerShot SX60.
References:
Chantler, P., & Driessens, G. (1995) Swifts: A Guide to the Swifts and Treeswifts of the World. Pica Press.
Gregory, P. (2017) Birds of New Guinea, Including Bismarck Archipelago and Boughainville. Lynx Edicions, Barcelona.
Wells, D. & Kirwan, G.M. (2019). Moustached Treeswift (Hemiprocne mystacea). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from https://www.hbw.com/node/55345 on 6 November 2019).