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U.S. NATIONAL MUSEUM BULLETIN 237 



birds were found at 10 widely scattered sites. Its increase in recent 

 years has been noted elsewhere in Florida by Sprunt (1954) and in 

 Maryland by Warbach (1958). The comments of Wells (1958) are 

 apropos: "Perhaps originally a bird of siiccessional vegetation within 

 the Eastern Deciduous Forest of North America, and of the oak open- 

 ings along the prairie-forest ecotone, the Indigo Bunting was un- 

 doubtedly restricted in numbers by the relatively closed canopy of 

 the climax forest * * *. In the East the opening of the forest 

 canopy by agriculture, logging and burning, and in the western grass- 

 lands the planting of trees, coupled with cessation of burning, con- 

 verted great areas into potential Indigo Bunting habitat. This 

 species has apparently responded to these changes with a great 

 increase in population and extension of range * * *." 



The ecological succession of forest floras in Maine during the past 

 century has been accompanied by marked changes in the indigo 

 bunting population at this northern limit of its breeding range. 

 Palmer (1949) traces the species decline there, which began in the 

 late 19th century and continued until the 1930's. As the automobile 

 replaced the horse, large acreages of pasture were allowed to revert 

 to forest, and the indigos started to reappear. "There has been a 

 marked increase during the past decade, the species again being noted 

 as a regular migrant and breeder, especially inland in southwestern 

 Mame * * *." 



The followiug table indicates some of the preferred breeding habitats 

 of this species and the breeding population densities. With few ex- 

 ceptions these habitats are all ecologically similar — open areas with 

 dense cover for nesting and feeding and the availability of high singing 

 perches. 



Reference 

 Warbach (1958) 

 Beecher (1942) 



Johnston (1947) 



Johnston and Odum (1956) 



Odum (1950) 



Norris (1951) 

 Stoddard (MS.) 

 Johnston (MS.) 



Fitch (1958) 



Brewer {fide Fitch, 1958) 



Breeding habitat 



residential area 



thicket 



unmodified woodland 



forest edge 



forest interior 



20-year-old grass-shrub 



field 

 hemlock sere: mesic 



shrubland 

 oak-chestnut sere: 



xeric shrubland 

 old field and fence-row 

 tung oil groves 

 overgrown area once 



cleared for building 



swamp thicket 



Population count or estimate 



1/acre 



5 (nests) /7.08 acres 

 2/26.87 acres 

 9-18 pairs/mile 

 3-9 pairs/ 100 acres 



4 pairs/100 acres 



7 pairs/100 acres 



18 pairs/ 100 acres 

 0.7 pairs/100 acres 



I pair/2-3 acres 



II pairs/77 acres 

 1 pair/2.7 acres 



1 pair/0.26 acre 



