Breeding Birds of Rothrock State Forest
The most extensive bird study in Rothrock State Forest has been the three Breeding Bird Survey (BBS) routes begun in 1992-93 by Greg Grove and the Special Area Project (SAP) trips to selected places by Greg and the author. Greg has continued to run two of the routes each year, namely the Rothrock State Forest and Broad Mountain routes, while the author took over the Tussey Mountain route in 1999. Each route covers 24.5 miles of state forest road, with 50 stops one-half mile apart. These are run once a year, usually in early June. All birds observed within a three-minute period are noted. U.S. Fish and Wildlife Service assesses the status of North American birds from data collected on approximately 2000 routes.
Eighty-eight species have been observed on the BBS routes, though four are probably not breeders. Another eleven species probably breed here in small numbers, for a total of about 95 breeders.
The BBS maps (see links below and within the text) show the geographical distribution of birds within the forest. The symbols represent the 1993-2004 mean count for individual stops. The Tussey Mountain route, the western-most, runs near the southern base of Tussey Mountain for the first 33 stops, then runs up over the ridge to end on the north side. The Rothrock State Forest route is the central one; it starts west of Alan Seeger Natural Area, twice crosses part of Big Flat, and ends near Whipple Dam State Park. The Broad Mountain route is eastern-most, starting near Greenwood Furnace State Park, traversing the flanks of Stone and Broad Mountains, before dropping to the valleys between the two Broad Mountains. Together, these cover the state forest’s predominant habitats.
The most common breeding birds are typical of central Pennsylvania. Red-eyed Vireo and Ovenbird, which together comprise about one in three breeding birds, can be found almost anywhere in the state forest. Yellow-billed Cuckoo, Acadian Flycatcher, Worm-eating Warbler, Hooded Warbler, and Scarlet Tanager can be found in similar numbers along all three BBS routes. Because of special habitat requirements, most other species tend to concentrate in certain parts of the state forest.
A number of species are more commonly found on the Tussey Mountain route than on the other two routes, particularly on the first 33 stops along the south side of the ridge. Here, the elevation is generally about 1200-1500 feet above sea level and conditions tend to produce taller and faster-growing oaks than in some of the higher elevations. The species more common here include Mourning Dove, Red-bellied and Pileated Woodpeckers, Eastern Wood-Pewee, Great Crested Flycatcher, Tufted Titmouse, Blue-gray Gnatcatcher, Wood Thrush, Cerulean Warbler, American Redstart, Rose-breasted Grosbeak, and Indigo Bunting. Many of this cohort attain some of their highest regional densities at the nearby Frankstown Branch of Juniata River IBA along the Lower Trail. Some of them also tend to be much more common in the southern half of Pennsylvania than in the northern half.
A set of boreal species whose ranges extend south into the Appalachians from Canada tend to be more commonly found at the higher elevations of the northeastern part of the state forest. These include Veery, Hermit Thrush, Black-throated Blue Warbler, Black-throated Green Warbler, Canada Warbler, and Dark-eyed Junco. Veery, Black-throated Blue Warbler, and Canada Warbler are particularly concentrated in the high valleys, of which Bear Meadows and Detweiler Run are the best examples. Acadian Flycatcher and Hooded Warbler, generally birds of more southern affinity, intermingle with the boreal birds in these valleys, while Worm-eating Warbler does likewise on the steep slopes.
Where ridge-top vegetation tends to be stunted and mountain laurel grows thickly or where the forest succession is several years old, Chestnut-sided Warbler, Common Yellowthroat, and Eastern Towhee are most commonly found. Their highest densities are probably on Big Flat and the tops of Broad and Thickhead Mountains.
Nick Bolgiano, January 2006
BBS maps in taxonomic order:
Yellow-billed Cuckoo Barred Owl
Great Crested Flycatcher
Black-throated Blue Warbler
Black-throated Green Warbler