THICKET ANIMALS 275 



B . Breeding on the ground among the shrubs and feeding in the open meadows 

 or prairies. 



1. Mammals: Common shrew (Sorex personatus) (L), the cottontail (H). 



2. Birds: Bobwhite (#), mourning dove (H) sometimes, northern yellow- 

 throat (L) sometimes, song sparrow (Z,) sometimes. 



C. Breeding on the shrubs and feeding in the forest edge and sometimes in 

 the open meadows or prairies. 



1. Mammals: None. 



2. Birds: (a) Low forest margin: song sparrow, goldfinch, indigo bunting, 

 northern yellowthroat, brown thrasher, and catbird. 



(ft) High forest margin: goldfinch, lark sparrow, chipping-sparrow, 

 field sparrow, indigo bunting, yellow warbler, redstart, loggerhead 

 shrike, mourning dove, catbird, cowbird, Baltimore oriole, bronzed 

 grackle, brown thrasher. 



D. Breeding in the trees of the forest and feeding in the prairies. 



1. Mammals: raccoon. 



2. Birds: Sparrow-hawk, sharp-shinned hawk, and several other hawks, 

 flicker, bronzed grackle. 



The list shows animals which breed in the margin of woods and often 

 feed not only there but in the prairies. Similar relations were noted by 

 Bates in the savannas along the middle Amazons. The advantage of the 

 forest margin lies in the facts of: (i) shade for the nocturnal and crepus- 

 cular forms; (2) abundant space in the thickets for nests; (3) large stiff 

 plants which accommodate the large animals: (a) places for the spiders to 

 stretch their nets; (b) plants large enough for the roosting- and nesting- 

 places of birds and larger insects; (4) protection from wind and from 

 winter freezing afforded by the forest. From the standpoint of food 

 relations many forest margin animals must be counted in with the 

 prairie forms. 



One of the most striking facts concerning the forest margin animals 

 is (a) their wide distribution and (6) their survival under agricultural 

 conditions. Many animals of importance as crop pests belong to forest 

 edges rather than to the forest proper. They take possession of the road- 

 sides when the country is cleared. Their distribution is a function of 

 the forest margin type of habitat. While it is a characteristic feature 

 of the forest border area, it is also to be found extending along the 

 wooded streams into the great plains and toward the east through the 

 forest area, as the shrubby bluff, the creek and river margin, the fired 

 area, and the marsh margin. While local and always leading a precari- 

 ous existence in unstable situations, this type of community, probably 



