Dr. Martin Moynihan 
2 
September 16, 1964 
The anatomical aspect of this project is one of interest, I believe, 
because of the taxonomic association with syringial structure. The sound- 
producing structure of the "primitive" passerines may be a function of selec- 
tion to produce "habitat adapted" sounds. The types of sound that the 
Dendrocolaptids, Furnariids, and Formicariids produce might not necessitate 
elaborate musculature. Yet these sounds are more adapted for the forest 
environment that "complex" sounds produced by an "advanced" anatomy. 
My "line of attack" to the problem is to measure the sound propa- 
gation characteristics of selected habitats using test tapes of different 
frequencies and sound structure made up in advance. Also, I want to 
utilize recorded natural sounds in propagation measurements. Then, after 
deducing what frequencies propagate best, worst, and are directional or 
non-directional, an analysis of what is actually found in different habitats 
will be made. I also plan to study syringial anatomy from a functional 
standpoint, looking for correlation with sound produced and habitat sound- 
selection. 
I am hoping to be able to study this problem in the tropics for 
two reasons. For the resident species there is a lifetime in one, almost 
constant, habitat for selection to operate. Further, the "primitive" 
passerines are more numerous in or confined to the tropics. Thus I feel 
that a study such as I propose would produce more useful data on tropical 
birds than on temperate, f j 
I hope all is going well. I shall be looking forward to your 
reply. 
Sincerely, 
Eugene S. Morton 
