There definitely is one bird species that went extinct, namely the Wake Island Rail. The bird was a flightless species of rail confined to Wake Island - numerous Pacific Islands have or had endemic flightless rail species, many of which have gone extinct in modern times. In the case of Wake Island, the bird had relatively stable numbers prior to the war, but was nowhere to be found in 1945. It's assumed that the Japanese garrison, starving from the US naval blockade of the island, ate them all, and despite being a wildlife lover, this is one species extinction where I personally feel "that's fair".

Another example would be the introduction of the Brown Tree Snake, native to the South Pacific, to the island of Guam. It's thought to have hitched a ride either on cargo ships or on aircraft landing gear from the US military flying from New Guinea, and since the war the snake population has exploded to some 2 million on the island.

The effects on the local ecosystem have been devastating, especially to bird species. The Guam flycatcher went extinct, local subspecies of Nightingale Reed Warbler, Bridled White-eye and Rufous Fantail went extinct, and local populations of Mariana Fruit Dove, Micronesian Honeyeater, White Throated Ground Dove, Micronesian Starling were extirpated. The Mariana Crow and Mariana Grey Swiftlet have barely hung on on the island. The Guam Kingfisher is extinct in the wild (it only survives in captivity) and the Guam Rail - a flightless relative of the Wake Island Rail - was also extinct in the wild, but has been successfully reintroduced. Although most of these extinctions occurred in the 1980s, they were all the result of predation from snakes who reached the island because of the war.