One advantage of studying two birds of a kind at the same time is to observe the talk between them, which has great interest for me. This pair were exceedingly talkative at first, uttering not only the usual musical three-syllable warble or call, which Lanier aptly calls the "heavenly word," but often soft twittering prattle, of varying inflection and irregular length, which was certainly the most interesting bird-talk I ever heard. When they could not see me they indulged in it more freely, with changing tones at different times, and after they became accustomed to the room and its inhabitants it was neither so frequent nor so earnest. Often at night, when one--perhaps in a dream--fell off the perch, I heard much low, tender talk, almost in a whisper, before all was quiet again; and when another bird flew wildly around the room, there was always a remark or two in an interested tone. The male did most of the talking, carrying on, often for a long time, a constant flow of what sounded marvelously like comments and criticisms, while his mate replied occasionally with the usual call. Certain notes plainly had a specific meaning, even to the others in the room. One in particular was peculiar and low, but upon its utterance every bird became instantly silent and looked at the cage, while the bluebirds themselves were so absorbed, gazing apparently into blank space, that I could easily put my hands on them before they observed me. For several minutes this low note would be repeated, and all the birds stare at nothing, till I began to feel almost uncomfortable, as I have done at similar staring at nothing on the part of animals. One can hardly resist the feeling that these creatures can see something invisible to our eyes. On one occasion, when the male uttered this note, the female was just about to eat; she stood as if petrified, with head halfway down to the food, for two or three minutes.