Not actually a finch, this species is now classified in the tanager family (Thraupidae ). It is dependent on ungrazed perennial grasses. This species was formerly known as Black-throated Finch or Canary-winged Finch. Juveniles are similar to adult females but are more heavily streaked, have a duller bill and are more buffy overall. These photos show 3 adult females, 2 juveniles and one adult male. Two subspecies are recognized. Birds on the Falklands are nominate while M. m. princetoniana is found on the adjacent mainland. Falkland birds are larger, with a larger bill and reduced yellow on their wings and tail. Canon PowerShot SX50 HS
Reference:
Jaramillo, A. (2018). White-bridled Finch (Melanodera melanodera). 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/62037 on 19 May 2018).