BIRDS OF THE ST. CROIX RIVER VALLEY 



13 



extent, occurring primarily in three distinct topographic settings: river 

 floodplains, ancient lake beds, and kettles associated with kettle and knob 

 topography in morainal areas. Soils of this habitat are usually acidic and are 

 composed of wet, decaying vegetation that in many instances gives the 

 ground a spongy texture. This habitat type is similar in several respects to 

 the original Boreal Forest. Because most of that habitat type has been 

 destroyed or greatly altered, vegetative characteristics and breeding bird 

 use of the two have been combined. 



Principal tree species of the Lowland Coniferous Forest include white 

 spruce, white cedar, balsam fir, yellow birch, black ash, and green ash. 

 Tamarack, American elm, and occasionally red maple, are also important 

 components of this habitat. Shrub layers are usually poorly developed in 

 Lowland Coniferous Forest; green ash and mountain holly are usually the 

 prevalent shrub species. Important species of the ground layer include blue 

 bead lily, bunchberry, creeping snowberry, wintergreen, Labrador tea, 

 Canada mayflower, false Solomon's seal, starflower, blueberry, wild cran- 

 berry, round-leaf sundew, downy yellow violet, and sphagnum moss. 



Principal breeding birds of this community include pileated woodpecker, 

 yellow-belUed flycatcher, olive-sided flycatcher*, black-capped chickadee, 

 red-breasted nuthatch*, winter wren*, hermit thrush, veery, solitary vireo, 

 black-and-white warbler*, Nashville warbler, northern parula*, magnolia 

 warbler*, yellow-rumped warbler*, ovenbird, northern waterthrush, com- 

 mon yellowthroat, brown-headed cowbird, purple finch*, pine siskin, chip- 

 ping sparrow, white-throated sparrow, and song sparrow. 



Black Spruce- Tamarack Bog 



Although not as extensive in distribution as other coniferous or deciduous 

 habitats, bogs are important to a large variety of breeding birds. This com- 

 munity exists primarily north of the Tension Zone and becomes frequent in 

 the Northern Highland. Scattered reUct bogs also occur in northern St. 

 Croix and Washington counties. Bogs are formed in ancient lake basins or in 

 outwash associated with morainal deposits. Bog soils are poorly developed 

 and are usually highly acidic, owing in part to anaerobic decomposition of 

 vegetation and temperature. 



Black spruce and tamarack are the two most important tree species in this 

 community. Mountain holly and bog birch are the main shrub layer species. 

 Ground-layer vegetation in these bogs is perhaps the characteristic that 

 separates this community from all others. Usually, the most important 

 family is Ericaceae (e.g., leatherleaf, Labrador tea). Herbaceous vegetation 

 in bogs usually contains several carnivorous plants including pitcher plant 

 and round-leaf sundew. Prevalent vegetation includes Labrador tea, leather- 

 leaf, bog rosemary, bog laurel, wild cranberry, buckbean, sphagnum moss, 

 cottongrass, awned sedge, brown sedge, and bluejoint grass. 



Principal breeding bird species include oUve-sided flycatcher, black- 

 capped chickadee, red-breasted nuthatch, winter wren, veery, black-and- 

 white warbler, Nashville warbler*, yellow warbler, yellow-rumped warbler, 

 common yellowthroat, red-winged blackbird, brown-headed cowbird, purple 

 finch, pine siskin, American goldfinch, chipping sparrow, white-throated 

 sparrow, swamp sparrow, and song sparrow. 



