These nondescript swiftlets were foraging over a shallow pond. They are now classified as endangered by IUCN. Recent declines have been attributed to insect loss from pesticides. On Saipan they are also threatened by exotic cockroaches which literally eat their nests. An effort to control cockroaches at nesting colonies is underway. These swiftlets are endemic to the Northern Mariana Islands but have been extirpated from Rota and Tinian. A small introduced population survives on Oahu, Hawaii. Formerly included in the genus Collacalia sometimes under the name "Guam Swiftlet." Formerly lumped with other Pacific Island swiftlets under the names Island Swiftlet, Gray Swiftlet, or Uniform Swiftlet (A. vanikorensis). Canon PowerShot SX60.
References:
BirdLife International 2016. Aerodramus bartschi. The IUCN Red List of Threatened Species 2016: e.T22728583A94990600. Downloaded on 26 October 2019.
Chantler, P., Boesman, P. & Kirwan, G.M. (2019). Mariana Swiftlet (Aerodramus bartschi). 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/55282 on 27 October 2019).
Chantler, P., & Driessens, G. (1995) Swifts: A Guide to the Swifts and Treeswifts of the World. Pica Press.
Pratt, H.D., Bruner, P., and Berrett, D.G. (1987) A Field Guide to the Birds of Hawaii and the Tropical Pacific. Princeton University Press