Absolute nest humidity (Pnest) and egg water vapor conductance (GH2O) of 295 taxa of living archosaurs are analyzed to test if Pnest and GH2O are correlated to nest types. Pnest is shown to be significantly higher in covered nest types than in non-covered nest types, likely because enclosed environments retain more humidity. Also, estimated Pnest of some waterbirds (e.g., grebes) with non-covered cup nests is high and comparable to that of covered nests, probably because the nest material is wet. Species that incubate eggs in humid nests are shown to have significantly higher GH2O than those incubating in regular nests (less humid), and these differences in GH2O between nester types prevent excess humidification or desiccation of the eggs. Therefore, Pnest and GH2O of the eggs appear to be closely related to nesting types in archosaurs, the latter of which can potentially be used to infer nest types of extinct archosaurs.