This is a split from the darker Island Collared-dove (Streptopelia bitorquata) based on a recommendation by Collar (2011) using the controversial Tobias scoring system. In this case significant vocal differences provide additional support for the split which has been accepted by Clements et al (2019) and del Hoyo et al. (2019), but not by Gill & Donsker (2019) nor by Christidis (2018). Philippine Collared-Dove, sensu stricto, is endemic to the Philippines but was introduced to Guam and the Northern Mariana Islands including Saipan in the 1970's. It is classified as "vulnerable" because of rapid declines on Luzon. This decline has been attributed to competition from Spotted Dove (Streptopelia chinensis) and Red Collared-Dove (Streptopelia tranquebarica), both of which appear to be better adapted to human disturbance. Canon PowerShot SX60.
References:
BirdLife International 2018. Streptopelia dusumieri. The IUCN Red List of Threatened Species 2018: e.T22727533A132177741. http://dx.doi.org/10.2305/IUCN.UK.2018-2.RLTS.T22727533A132177741.en. Downloaded on 29 October 2019.
Collar, N.J. (2011) Species limits in some Philippine birds including the Greater Flameback Chrysocolaptes lucidus. Forktail 27: 29-38.
Christidis et al. 2018. The Howard and Moore Complete Checklist of the Birds of the World, version 4.1 (Downloadable checklist). Accessed from https://www.howardandmoore.org.
Clements, J. F., T. S. Schulenberg, M. J. Iliff, S. M. Billerman, T. A. Fredericks, B. L. Sullivan, and C. L. Wood. 2019. The eBird/Clements Checklist of Birds of the World: v2019. Downloaded from http://www.birds.cornell.edu/clementschecklist/download/
del Hoyo, J., Collar, N. & Kirwan, G.M. (2019). Philippine Collared-dove (Streptopelia dusumieri). 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/467130 on 29 October 2019).
Gill, F & D Donsker (Eds). 2019. IOC World Bird List (v9.2). doi : 10.14344/IOC.ML.9.2. Available at http://www.worldbirdnames.org/
Goodwin, D. (1983) Pigeons and Doves of the World. Cornell Univ. 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