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A previous account has established that the newt Taricha rivularis returns to the home segment of breeding stream after displacement for major distances.' Of the questions raised by this finding, the present paper deals with two. One concerns the route taken by the homing animals, principally whether it is terrestrial or aquatic; the other pertains to the timing of the homing journey, with primary reference to its initiation and completion. These and other aspects of our studies on newt homing have been touched upon in other publications,'-3 especially in a book on salamander biology,4 but in this and a series of papers to follow, our findings will be presented in more detailed, definitive form. Aerial photographs and descriptions of the study area in the coastal mountains of Sonoma County have already been published;' 5 the streams and topography of the area are further shown in Figure 1. Pepperwood Creek, especially the portion ("experimental stretch") designated by the numbered segments or "stations," is the stream within which our most intensive homing studies have been based, but reference will also be made to important evidence on the course and timing of homing from interstream displacements. Intrastream Displacements.-Of the numerous displacements that have been made within the experimental stretch, three lend themselves most directly to clarification of the questions at hand. Figure 2, although published elsewhere,4 is reproduced here because it serves so well to introduce these questions and also bears materially on their answers. The histogram shows the locations of stream recaptures of animals displaced for a straight-line distance of approximately 1 mile. (On recapture the animals were given a toe marking to avoid recording the same animals again on subsequent encounters.) One will note the virtual absence of any animals in the long stretch of stream intervening between the home area and the release site. Most of the animals were recaptured in the home segment of stream, and almost all of the remainder were at or near the release site. Rivularis is aquatic only during the breeding period, and annually throughout this season we patrol the entire experimental stretch regularly and intensively. We can thus be sure that animals recaptured in the home segment of stream during the later years following displacement have not re-entered the stream at points en route home, either to use it as a homing pathway or perhaps for any navigational cues it might afford them in resuming their terrestrial homeward migration. Otherwise, we would have encountered them at intermediate sites between the displacement and home areas. However, the design of this experiment leaves unanswered certain crucial questions. First, recording of the locations of recaptures was not begun until the next breeding season, one year following displacement; accordingly, the histogram gives no indication whether, or for what distances, the animals may have executed a homeward migration in the stream channel during the remainder of the same breed-

Course and timing of the homing migration in the newt Taricha rivularis.