Acid Shale Pine Forest Birds 



The following list of birds includes species documented at a camp on BLM land in T16N 

 R25E S30SE (3300 ft elevation) near War Horse Lake in Petroleum County, Montana. The site 

 is atop an outcrop of acid shale of the Bearpaw Formation forming a low east-west tending ridge 

 in several adjacent sections of Petroleum and Fergus counties. The vegetation surrounding the 

 ridge at slightly lower elevation is sagebrush grassland, but the acid shale outcrop soils support 

 forests dominated by ponderosa pine {Finns ponderosa) and a shrub layer dominated by 

 horizontal juniper {Juniperus hohzontalis). Canopy cover of forbs is sparse, the herbaceous 

 layer is dominated by sun sedge {Carex pemisylvatiica) and five grass species; large areas of bare 

 soil are common. This plant community is unique in Montana (Lesica 1987) and has been little 

 studied. 



The site where the following bird observations were made is within the largest, best- 

 developed and most diverse example of acid shale pines on public lands (Lesica 1987). The list 

 of breeding season birds is necessarily incomplete, as the camp was occupied only during 17-22 

 June 1999. Nevertheless, it provides a baseline inventory of the bird species associated with this 

 unique endemic plant community 



Common names of birds follow the A O.U. Check-list of North American Birds, seventh 

 edition (A OU. 1998). 



Mallard breeds (nest with 9 eggs, predated nest with 6 eggs, both in forest), dates- 19 



Northern Goshawk: transient (immature in forest), dates- 18 



American Kestrel: breeds (nest in pine snag), dates- 19,20,21,22 



Killdeer: transient (flyover); dates- 20 



Upland Sandpiper: breeds (adults with yng at forest edge); dates- 19,20,21,22 



Mourning Dove: breeds (nest with eggs); dates- 17,18,19,20,21,22 



Common Nighthawk: probably breeds (displaying males); dates- 17,18,19,20,21,22 



Common Poorwill: probably breeds (calling males), dates- 17,18,19,20,21,22 



Hairy Woodpecker: probably breeds (pair), dates- 19,20,21,22 



Northern Flicker: breeds (nest in pine snag), dates- 18,19,20,21,22 



Western Wood-Pewee: probably breeds (territorial males), dates- 17,18,19,20,21,22 



Dusky Flycatcher: breeds (nest with 5 eggs [3 cowbird]); dates- 17,18,19,20,21,22 



Clark's Nutcracker: transient (one in pines), dates- 20 



American Crow; transient (flyover); dates- 20 



Mountain Chickadee: probably breeds (pairs), dates- 18,19,20,21,22 



Red-breasted Nuthatch: probably breeds (pair), dates- 21 



House Wren: breeds (3 boxes with 7-egg clutches, 1 with 7 yng); dates- 17,18,19,20,21,22 



Mountain Bluebird: breeds (3 nest boxes with broods of 5 yng), dates- 17,18,19,20,21,22 



American Robin, breeds (nest with 3 yng), dates- 17,18,19,20,21,22 



Yellow-rumped Warbler: (Audubon's) probably breeds (males singing), dates- 18,19,20,21,22 



Spotted Towhee: probably breeds (singing male), dates- 19,20,21 



Chipping Sparrow: breeds (aduh with food), dates- 18,19,20,21,22 



Vesper Sparrow: probably breeds (singing males at forest edge); dates- 18,19,20,21 



Western Meadowlark: breeds (adults with food at forest edge); dates- 17,18,19,20,21,22 



Brown-headed Cowbird: breeds (parasitized Dusky Flycatcher nest); dates- 20,21,22 



Red Crossbill: probably breeds (flocks of males + females), dates- 17,18,19,20,21,22 



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