Synonyms for Tree Swallow (same or very similar meaning)
WordNet sense 1 (bluish-green-and-white North American swallow; nests in tree cavities):
white-bellied swallow, Iridoprocne bicolor
WordNet sense 2 (of Australia and Polynesia; nests in tree cavities):
Hirundo nigricans, tree martin
From the ODE community, based on WordNet
add/edit