COMMUNITY ORGANIZATION: METABOLISM 



513 



MATURE POPLAR COMMUNITY 



Baltimore Oriole 

 Chickadee 

 Least Flycatcher 

 Rose - bstd Grosbeak 

 Willow Thrush 



Hairy £f Downy 

 Woodpeckers 



Qicera 

 Saperda 



Yellow Warbler 

 Redwinged Blackbird 

 Bronze Grackle 



Cutworms 

 Grasshoppers 

 Click Beetles 



Pocket Gophers 

 Ground Squirrels 



Fig. 170. Food web interrelations between communities and ecotones in the aspen parkland of 

 Canada. ( From Hesse, Alice, and Schmidt, after Bird. ) 



nation or aestivation, and over much greater 

 distances in migration (Chap. 28). Aside 

 from such periodic seasonal events, fre- 

 quent visits into another food web occur, 

 and are well shown in Figure 170, showing 



feeding interrelations in the aspen park- 

 land of Canada studied by R. H. Bird 

 (1930). 



Two classic food chains are those of 

 Darwin (1859) of an English meadow, 



