_Aphanolimnas monasa_ (extinct?), _Ptilinopus porphyraceus_, and _Ducula oceanica_ are the only species of birds which have reached Micronesia directly from Polynesia. There are in Micronesia, as Mayr (1941b: 204) points out, eight species "which are members of typically Polynesian species or genera" and six species which are either Papuan or Polynesian. The relationships between Polynesian and Micronesian birds is evident, but insofar as the pathways of colonization are concerned the majority of these Micronesian species listed by Mayr have come from elsewhere than Polynesia and the birds of these two areas are thought to have arisen from common ancestors. _Aphanolimnas_, _Ptilinopus_, and _Ducula_ apparently invaded Micronesia from Central Polynesia _via_ the Marshall Islands through a rather continuous chain of islands and atolls. _Aphanolimnas_ is known only from Kusaie in the extreme eastern part of the Carolines while _Ptilinopus_ and _Ducula_ are known from the Marshalls, Carolines, and Palaus. MELANESIAN COMPONENT The Papuan or Melanesian Region (New Guinea, Bismarck Archipelago, Solomon Islands) has supplied to Micronesia its greatest number of endemic land and fresh-water residents. Fifty kinds of birds belonging to the following species reached Micronesia from Melanesia: _Nycticorax caledonicus_, _Megapodius lapérouse_, _Ptilinopus roseicapillus_, _Gallicolumba xanthonura_, _G. canifrons_, _Caloenas nicobarica_, _Halcyon cinnamomina_, _Trichoglossus rubiginosus_, _Collocalia inquieta_, _Edolisoma tenuirostre_, _Rhipidura rufifrons_, _Metabolus regensis_, _Monarcha godeffroyi_, _M. takatsukasae_, _Colluricincla tenebrosa_, _Aplonis opacus_, _A. pelzelni_, _A. corvinus_ (extinct?), _Cleptornis marchei_, _Myzomela cardinalis_ (probably by way of Southern Melanesia), _Rukia palauensis_, _R. oleaginea_, _R. ruki_, _R. sanfordi_, _Erythrura trichroa_. The colonization of Micronesia by these species has probably extended over a considerable period of time. _Megapodius_, _Trichoglossus_, and _Aplonis corvinus_ may represent older colonizations which have become well differentiated from the ancestral forms; _Nycticorax_, _Myzomela_, and _Erythrura_ may have become established later and have had "less time" to become modified from the ancestral forms. Birds from Melanesia have reached Micronesia probably by direct flight to the Caroline Islands. Aided by favorable winds which blow from the southwest, south and southeast during the period from May to November, birds, particularly the young of the year, might conceivably be blown in the direction of the Carolines, where 57 percent of the birds derived from Melanesia reside. The Palaus are populated with 15 percent, the Marianas with 28 percent, and the Marshalls (lacking "high" islands) with none; these may be secondary colonizations from the Carolinas excepting _Ptilinopus_, _Megapodius_, _Gallicolumba canifrons_, _Cleptornis_, and _Colluricincla_. The