NO. 7 FLOCKS OF NEOTROPICAL BIRDS — MOYNIHAN I37 



possible that species of tanagers, honeycreepers, and neotropical 

 finches that have developed the habit of associating in mixed flocks, 

 in any capacity or social role, may tend to survive better in relatively 

 unfavorable or partly isolated habitats within the Tropics and/or in- 

 vade such habitats more successfully than related and otherwise simi- 

 lar species that have not developed such habits. 



ACKNOWLEDGMENTS 



Most of this study was subsidized by a grant from the National 

 Science Foundation (NSF G 5523). 



Mr. David Fairchild and Mr. James Ambrose, Jr., provided valu- 

 able assistance in making the counts of social reactions within mixed 

 flocks. I am also greatly indebted to them for many useful comments 

 and suggestions. This study would not have been possible without 

 their help. I must thank also Dr. Alexander Wetmore, Dr. David 

 Snow, Mr. W. John Smith, and Mr. Eugene Eisenmann for giving 

 me much useful information, and Dr. Herbert Friedmann and 

 Mr. H. G. Deignan for letting me use certain specimens from 

 the collection of the U.S. National Museum. 



BIBLIOGRAPHY 

 Amadon, D. 



1950. The Hawaiian honeycreepers (Aves, Drepaniidae) . Bull. Amer. Mus. 

 Nat. Hist., vol. 95, pp. 157-262. 

 Andrew arth a, H. G., and Birch, L. C. 



1954. The distribution and abundance of animals. Chicago. 

 Bastock, M. ; Morris, D. ; and Moynihan, M. 



1953. Some comments on conflict and thwarting in animals. Behaviour, vol. 

 6, pp. 66-84. 

 Bates, H. W. 



1863. The naturalist on the River Amazons. London. 

 Belt, T. 



1874. The naturalist in Nicaragua. London. 

 Brown, W. L., Jr., and Wilson, E. O. 



1956. Character displacement. Syst. Zool., vol. 5, pp. 49-64. 

 Butler, A. G. 



1894. Foreign finches in captivity. London. 

 Chapin, J. P. 



1932. The birds of the Belgian Congo. Part 1. Bull. Amer. Mus. Nat. 

 Hist., vol. 65, pp. 1-756. 

 Chapman, F. M. 



1917. The distribution of bird life in Colombia. Bull. Amer. Mus. Nat. 



Hist., vol. 36, pp. 1-729. 

 1926. The distribution of bird life in Ecuador. Bull. Amer. Mus. Nat. Hist., 

 vol. 55. PP- 1-784. 



