Periodical Literature. 191 



Charles C. Adams, University of Illinois, 



Ecology has disclosed a new and interesting field of 



of study in his paper upon "The Ecological 



Birds. Succession of Birds." His thesis is that 



just as there is a succession of vegetation, 

 so there is a succession of birds on a given area, dependent upon 

 the successive changes in vegetation. For example, on Isle 

 Royale in Lake Superior, the author observed that certain birds 

 accompanied the invasion of open bogs by Tamarack, Black 

 Spruce and Arbor Vitae. These birds are the Red-breasted 

 Nuthatch, Yellow-bellied Flycatcher, Golden-crowned Kinglet, 

 Cedar Waxwing, Chickadee, Canada Jay, White-winged Cross- 

 bill. Where alders abound the conditions are favorable for the 

 Redstart and the White-throated Sparrow. But later as the bog- 

 conifer forest becomes continuous and dominant, the Waxwing, 

 Redstart and White-throated Sparrow diminish in numbers and 

 finally disappear. Still later as the swamp becomes eliminated 

 by the Spruce-Balsam forest, the Yellow-bellied Flycatcher is ex- 

 cluded and various species of woodpeckers come in. In a similar 

 manner he traces the changes in bird life which accompany the 

 successive stages in the reforestation of burned areas. 



While birds from their nature are more mobile than plants in 

 their occupancy of an area, yet in the breeding season, pairs of 

 birds tend to space themselves and to become relatively sedentary 

 and thus they react to the laws of invasion and succession in a 

 manner similar to plants. 



C. D. H. 



The Ecological Succession of Birds. The Auk, Vol. 25, No. 2, April, 

 1908. 



It appears from recent investigation accord- 

 Longevity ing to Wm. Crocker, that delayed germina- 



of tion in seeds is generally due to the char- 



Seeds. acter of the seed coats rather than to the 



so-called dormancy of protoplasm. The 

 prevention of germination is due to the fact that the seed coat 

 shuts out for a time conditions favorable to the growth of the 

 embryo. This is accomplished by the exclusion of water or 

 oxygen, or perhaps chemical compounds necessary for germina- 

 tion. 



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