74 



The cat-tail association has, by its own growth, built up a 

 firmness of soil that gives the sedges the conditions necessary 

 for their occupancy. Thus the story goes on. The climax 

 society is that of the elms, the society which, if left undis- 

 turbed, would eventually conquer the entire marsh. The 

 zones of plant life are very evident, and the method of succes- 

 sion comparatively simple. In the case of the animals, other 

 factors enter, and conceal the order of progression, which 

 nevertheless exists as with the plants. An area occupied by 

 Grebes to-day may be occupied by Rails to-morrow. As the 

 sedges encroach upon the cat-tails, so the Swamp Sparrows 

 crowd upon the Rails. A detailed understanding of the 

 succession requires years of close observation, and the results 

 to be derived from such observation are, of course, not yet 

 forthcoming. It was with this in view that the map of the 

 area under consideration was made. By following it from 

 year to year, it is hoped that a more definite knowledge of the 

 succession will be gained. 



PART II. THE LIFE HISTORY AND ECOLOGY OF 

 THE RED-WINGED BLACKBIRD. 



The order of this discussion will be that of the various 

 phases of the life history of the bird. Beginning with the 

 spring migration, we shall consider in turn mating, nesting, 

 flocking, fall migration, and other general phases not included 

 in the above, such as enemies, plumage, and food. Each 

 division will be prefaced with a summary of the principal 

 literature upon the pha^e under consideration, and will in- 

 clude a discussion of the changes occurring in the environment 

 during that period. 



Spring Migration. 

 Summary of the Literature. — In view of the general interest 

 that is taken in this phase of a bird's life history, remarkably 

 little definite information concerning the Redwing's migration 

 has been published. According to Wilson (1831), the species 

 is migratory north of Maryland. It is ''found during winter 

 in immense flocks, sometimes associated with Purple Grakles, 



