a mouse over a rat at this particular time. It is, of course, not necessary to assume that the bird "reasoned" about the matter at all, or that it consciously endeavored to convey its desires to me, or that it had formed a fixed determination that it wanted a mouse and not a rat, or that it has any subjective conception of the difference between rats and mice; but the fact remains that it refused the rat, even when there was no mouse visible as an alternative, and that it went to the place where it had learned from experience that mice are kept, and there waited until its mouse preference was satisfied. Only mice are kept at that place. But mice are also kept in the shop and Rhody has taken both rats and mice from me there. There is a suggestion here that he is aware of this distinction and that he went to the mouse placein the knowledge that only mice camefrom there. However, I do not insist upon this interpretation of his behavior. The physical facts bearing upon this episode and which may have been at the bottom of it all are: (1) Rhody was not very hungry. He was not in need of food. (2) The rat was white. (3) The mice were not white, but a little lighter than the usual mouse color. (4) Practically none of the natural food of road-runners is white. (?) (5) Rhody, Archie and Terry have always, unless very hungry, accepted white mice less readily than dark ones. (6) The young rat offered was about the same size as the mouse; hence size cut no figure. (7) The rat, when (as far as Rhody could tell) abstracted from the mouse can, was still refused. (8) The mouse, placed along-side of it, was taken. Hence the choice of food, in his not-very-hungry state, was based on color. (?) So much for the matter of choice; but we are still left with at least apparent knowledge on the part of the bird that there was greater certainty of securing the food preferred at the moment at one place rather than the other. This would seem to imply ability to learn and arrive at some sort of a weighing of certainties against uncertainties as a basis upon which to act. But I do not insist upon this interpretation either. July 14th. Rhody was around the place all day. His interest in his nest and the magpies was negligible; in fact he did not visit the nest at all. He was given a mouse and a rat during the day, but did not display for either. July 15th. Rhody had his rat in the morning, without display. I was absent during the afternoon until about 5:45 P.M. Julio says R was not seen, although looked for, during my absence. On my return I sat in the shade near the oval lawn reading Sutton's chapter on his pet road-runners, in his "Birds in the Wilderness", which I had just obtained. I was mentally comparing the behavior of his birds with Archie and Terry's when a rattle- boo sounded off to my left and Rhody appeared in the driveway near- by--an odd coincidence. When he came up to me he was the dustiest