Baldpate Mountain Important Bird Area (IBA)

American Redstart territorial singing © Sharyn Magee

Baldpate Mountain is a very special place

Surrounded by a biological desert, Baldpate Mountain is a hotspot of biodiversity. Baldpate is part of the Greater Sourland Mountain Ecosystem, a high area formed by erosion resistant diabase after the softer surrounding rocks eroded away. As a raised wetland with poor drainage, this ecosystem has resisted development, leaving the two largest contiguous forested areas in central New Jersey. Because of its steep slopes and history of deer hunting, Baldpate Mountain has retained the greatest expanse of healthy understory in the Greater Sourland Ecosystem. The Sourland Mountain has a greater area of contiguous forest, but Baldpate has a larger expanse of high quality understory with four areas of extensive understory dominated by native plants, primarily Spicebush.

Because of the combination of contiguous forest, high quality understory, and its location as the meeting place of Southern and Northern species, Baldpate Mountain has the highest concentration of nesting Nearctic-neotropical birds in New Jersey and the largest number of species of breeding Nearctic-neotropical migrants in central New Jersey. The interior forest has breeding Cerulean Warblers, Hooded Warblers, Kentucky Warblers, and Worm-eating Warblers, Wood Thrush and Veery, all New Jersey species of conservation concern. The forest has a mosaic of habitats, with naturally occurring treefall gaps supporting a tangle of vegetation that supports a different group of species, including the American Redstart. Baldpate also supports edge breeding species, especially where there is a soft edge between the forest and the open areas, giving a total of thirteen breeding wood warblers, which makes Baldpate a birding mecca. The area attracts large numbers of species of migrating Nearctic-Neotropical migrants, as well. Several New Jersey threatened raptors, including Barred and Long-eared Owls and Red-shouldered Hawks, use Baldpate for at least part of their life-cycle. Cooper’s Hawks, a New Jersey species of conservation concern, breed at Baldpate.

WCAS has been monitoring bird populations at Baldpate since 2000 and conducted two breeding studies. NJ state threatened Long-eared Owl roosts in Baldpate’s dense evergreens.
Long-eared Owl NJ State Threatened © Sharyn Magee
Healthy spicebush understory (below) at Baldpate provides dense nest cover in Spring. Central and South America bound migrants fatten up on its lipid-rich red berries in Fall.
Healthy spicebush understory at Baldpate © Sharyn Magee
Blue-wing Warbler breeds at Baldpate © Sharyn Magee
View of Delaware River from summit of Baldpate Mountain, Hopewell Township. Baldpate is home to uncommon and rare wildlife. Photo © Fairfax Hutter.
Baldpate is Mercer County’s highest mountain with views of the Delaware River, Trenton and Philadelphia.

Baldpate Mountain Trail Map PDF

Baldpate hiker © Pat Sziber
Over 12 miles of trails meander through 1,500 mostly forested acres, diabase boulders, and historic ruins
Combo Aerial/Terrain photo of Ted Stiles Preserve at Baldpate Mountain showing narrow ridge with steep relief and preserved lands in brighter green
‘Devil’s in the diabase’—Baldpate is part of the Greater Sourland Mountain Ecosystem, a high area formed by erosion resistant diabase after the softer surrounding rocks eroded away. As a raised wetland with poor drainage, this ecosystem has resisted development, leaving the two largest contiguous forested areas in central New Jersey. Diabase weathers into mineral rich clay soils that support distinct, uncommon plant communities.
Baldpate Mountain was designated as an Important Bird Area due to all these factors. For an area to support this number of birds, it must support an intact ecosystem with other taxa, especially native plants and insects, having healthy populations and diversity. In addition to rare birds, Baldpate supports rare reptiles, including NJ species of special concern Eastern Box Turtle and Agkistrodon contortrix and rare amphibians, including the Fowler’s Toad and Spotted Salamander.

While Baldpate has an intact ecosystem, it is also highly stressed. Baldpate is at the lower size limit for an interior forest habitat and its shape is long and narrow, increasing its vulnerability to edge effect. Increased edge effect increases the number of invasive species, especially non-native plants, and the Brown-headed Cowbird, a nest parasite. Any reduction in size of Baldpate would have serious consequences, both by threatening native plants and increasing the incidence of Brownheaded Cowbird nest predation. Nest predators, such as the Eastern Chipmunk, which have higher concentrations on the edges and in disturbed areas, would thrive. The proposed PennEast pipeline runs along the north slope of the mountain and would change one of the high quality interior forest habitats into edge habitat and bring the edge closer to the other areas of high quality habitat, seriously degrading an already stressed ecosystem.

Long-spurred Violet (Viola rostrata) NJ Species of Concern © Tyler Christensen
Healthy bird populations indicate healthy, diverse populations of other taxa, notably the plants and insects upon which the birds depend. Above: rare Long-spurred violet (Viola rostrata) © Tyler Christensen; right: Dutchman’s breeches (Dicentra cucullaria); other wildflowers © Fairfax Hutter; top: hiker © Pat Sziber; spicebush & all bird photos this page © Sharyn Magee unless otherwise noted.
Showy Orchis with Wild Geranium © Fairfax Hutter
Delicate Hepatica vulnerable to deer browse © Fairfax Hutter
Tall Tulip Tree blossom © Fairfax Hutter
Bloodroot, one of the first "Spring ephemerals" to bloom © Fairfax Hutter
31 of the 32 Nearctic-neotropical migrants including 15 Warblers who breed at Baldpate
Four of the 90 Nearctic-neotropical migrants who use Baldpate as critical stop over habitat
Baldpate’s Wintering Residents and Winter Migrants
Baldpate’s Year Round Residents
Birds reported to Baldpate “Hot Spot” on e-Bird

Snow Goose
Canada Goose
Mute Swan
Wood Duck
American Black Duck
Common Merganser
Wild Turkey
Common Loon
Great Cormorant
Double-crested Cormorant
Great Blue Heron
Green Heron
Black Vulture
Turkey Vulture
Swallow-tailed Kite
Golden Eagle
Northern Harrier
Sharp-shinned Hawk
Cooper’s Hawk
Bald Eagle
Red-shouldered Hawk
Broad-winged Hawk
Red-tailed Hawk
Least Sandpiper
American Woodcock
Spotted Sandpiper
Laughing Gull
Ring-billed Gull
Herring Gull
Rock Pigeon
Mourning Dove
Yellow-billed Cuckoo
Black-billed Cuckoo
Eastern Screech-Owl
Great Horned Owl
Barred Owl
Long-eared Owl
Northern Saw-whet Owl
Common Nighthawk
Eastern Whip-poor-will
Chimney Swift
Ruby-throated Hummingbird

Belted Kingfisher
Red-headed Woodpecker
Red-bellied Woodpecker
Yellow-bellied Sapsucker
Downy Woodpecker
Hairy Woodpecker
Northern Flicker
Pileated Woodpecker
American Kestrel
Peregrine Falcon
Olive-sided Flycatcher
Eastern Wood-Pewee
Yellow-bellied Flycatcher
Acadian Flycatcher
Alder Flycatcher
Willow Flycatcher
Least Flycatcher
Eastern Phoebe
Great Crested Flycatcher
Eastern Kingbird
White-eyed Vireo
Yellow-throated Vireo
Blue-headed Vireo
Philadelphia Vireo
Warbling Vireo
Red-eyed Vireo
Blue Jay
American Crow
Fish Crow
Common Raven
Northern Rough-winged Swallow
Purple Martin
Tree Swallow
Bank Swallow
Barn Swallow
Cliff Swallow
Carolina Chickadee
Black-capped Chickadee
Carolina x Black-capped Chickadee (hybrid)
Tufted Titmouse
Red-breasted Nuthatch
White-breasted Nuthatch
Brown Creeper
House Wren
Winter Wren
Marsh Wren
Carolina Wren
Blue-gray Gnatcatcher
Golden-crowned Kinglet
Ruby-crowned Kinglet
Eastern Bluebird
Gray-cheeked Thrush
Gray-cheeked/Bicknell’s Thrush
Swainson’s Thrush
Hermit Thrush
Wood Thrush
American Robin
Gray Catbird
Brown Thrasher
Northern Mockingbird
European Starling
Cedar Waxwing
Worm-eating Warbler
Louisiana Waterthrush
Northern Waterthrush
Golden-winged Warbler
Blue-winged Warbler
Brewster’s Warbler (hybrid)
Golden-winged/Blue-winged Warbler
Black-and-white Warbler
Prothonotary Warbler
Tennessee Warbler
Nashville Warbler
Connecticut Warbler
Mourning Warbler
Kentucky Warbler
Common Yellowthroat
Hooded Warbler
American Redstart
Cape May Warbler
Cerulean Warbler
Northern Parula
Magnolia Warbler
Bay-breasted Warbler
Blackburnian Warbler
Yellow Warbler
Chestnut-sided Warbler
Blackpoll Warbler
Black-throated Blue Warbler
Palm Warbler
Pine Warbler
Yellow-rumped Warbler
Yellow-throated Warbler
Prairie Warbler
Black-throated Green Warbler
Canada Warbler
Wilson’s Warbler
Yellow-breasted Chat
Grasshopper Sparrow
American Tree Sparrow
Chipping Sparrow
Field Sparrow
Fox Sparrow
Dark-eyed Junco
White-crowned Sparrow
White-throated Sparrow
Savannah Sparrow
Song Sparrow
Lincoln’s Sparrow
Swamp Sparrow
Eastern Towhee
Summer Tanager
Scarlet Tanager
Northern Cardinal
Rose-breasted Grosbeak
Blue Grosbeak
Indigo Bunting
Red-winged Blackbird
Common Grackle
Brown-headed Cowbird
Orchard Oriole
Baltimore Oriole
House Finch
Purple Finch
Pine Siskin
American Goldfinch
House Sparrow