February 29, 1936 49 4. more minutes, we saw a pair of Bushtits lay the very first material for a nest. Here also, some of us learned more about the meaning of bird notes as a result of explanation by Dr. Jimmell and demonstration by the birds. As contrasted with the Ruby- Crowned Kinglet, where the birds forage separately and constantly utter "segregation" notes - notes uttered to insure the maintenance of a foraging range for each bird- here we had a bird that forages either in flocks or constantly in pairs and utter "location" notes - notes to insure each bird that the other or others are still close at hand. These notes probably account for the fact.