84 Grinnell, Sequestration Notes. Uau. 



5 soon passed and the rest of the month was rather even weather, 

 with not a low temperature. On March 25 I found that Piping 

 Plovers had arrived on the beach, but I saw neither Sanderlings 

 nor Red-backs. 



April 1 was warm, sunny and springlike. "Many Geese are 

 going over the beach and I find that the numbers of Piping Plovers 

 have increased since March 25. Saw two Sanderlings whch may 

 or may not have been the birds of last winter." 

 52 Cedar St., Maiden, Mass. 



SEQUESTRATION NOTES. 



BY JOSEPH GRINNELL. 1 



There is every reason to believe that the voices of birds have 

 been subject to a process of evolution which has led from the sim- 

 plest beginnings to a condition which is rather complicated in the 

 higher present-day species. The first sounds uttered by primitive 

 birds were doubtless entirely of an incidental nature, due to expul- 

 sion of air under stress of pain or fear, or simply of physical impact. 

 According to one theory (Witchell, 'The Evolution of Bird -Song,' 

 London, 1896) the first specialization accompanied combat and 

 involved a meaning of defiance or intimidation; from this it was 

 an easy step to notes conveying the idea of alarm to other indi- 

 viduals of the same species. 



Whatever the course in the early development of bird voices, 

 it is obvious to any field student that in the higher existing birds 

 an often very elaborate system of cries or calls obtains, with an 

 associated wide range of meaning; as witness the Titmouses and 

 Ruby-crowned Kinglets. Some of the meanings, in certain species, 

 have been demonstrated beyond all question of doubt. The less 

 obvious meanings will have to be worked out by slow process, and 

 exceeding care be taken to avoid mere guess-work. 



1 Contribution from the Museum of Vertebrate Zoology of the University of California. 



