d4^j Correspondence. [ April 



birds been sailing overhead at a considerable height (a common habit), 

 probably they would not have been seen by the hunters, yet every move 

 of the latter might have been observed by the birds; the presence and 

 actions of the pack of hounds would almost certainly have attracted the 

 attention of any birds on the wing, even had they just left the supposed 

 nearest roost, eight miles away. Furthermore the observations as re- 

 ported do not exclude the possibility that the vultures were already in 

 the hole where the carcass was thrown. Either of these suggestions 

 seems easier to entertain than that the buzzards were guided to the car- 

 cass by a means outside of human experience. 



Certainly in the classic experiments of John Bachman as reported by 

 Audubon (Orn. Biogr., Vol. 2, 1835, pp. 44-49), both Turkey and Black 

 Vultures, showed their absolute dependence for food-finding upon the 

 sense of sight, and ignored food they would have found immediately had 

 they been able to smell, much less had they been possessors of an "occult" 

 food-finding faculty. Consider the following extract, "The most offensive 

 portions of the offal were now placed on the earth; these were covered 

 over by a thin canvass cloth; on this were strewed several pieces of fresh 

 beef. The Vultures came, ate the flesh that was in sight, and although 

 they were standing on a quantity beneath them, and although their bills 

 were frequently within the eighth of an inch of this putrid matter, they 

 did not discover it. We made a small rent in the canvass, and they at 

 once discovered the flesh, and began to devour it. We drove them away, 

 replaced the canvass with a piece that was entire; again they commenced 

 eating the fresh pieces exhibited to their view, without discovering the 

 hidden food they were trampling upon." 



Dr. GrinnelPs thesis is that certain call-notes may have been fixed by 

 selection on account of their utility in preventing individual birds from 

 seeking food in areas recently searched by another bird. His examples 

 are the Ruby-crowned Kinglet and Audubon's Warbler. The eastern 

 representative of the latter bird, the Myrtle Warbler, is similar in habits 

 and has a very similar call-note. This is uttered frequently whether by 

 the few warblers or perhaps single wintering bird in a given locality, or 

 by the individuals of a perfect swarm of the warblers such as winter in 

 coastwise parts of the Carolinas. In the former case risk of searching the 

 same area twice practically does not exist ; in the latter that the same area 

 will be gone over more than once daily is inevitable. In either event 

 the call-note cannot have the significance hypothecated by Dr. Grinnell. 



In fact birds do habitually go over the same places. A tree infested 

 by bark-beetles is not freed of its pests by continuous work on the part of 

 woodpeckers; on the contrary they return to it again and again. Our 

 feeding-stations with practically inexhaustible supplies are periodically 

 visited, and tempting as they are, usually do not localize the birds. These 

 have other business elsewhere, but they return. Many observations by 

 the writer, confirmed by comparing notes with others, indicate that vari- 



