Guided By Birds: Avian data to guide Clayton Hill restoration

This post was written by Robin Eng, Ecological Project Manager for the Pittsburgh Parks Conservancy.

Forest restoration is a moving target. To measure the impacts and progress of restoration efforts practitioners must choose certain quantifiable elements of an ecosystem that can indicate habitat quality. For the restoration site in Frick Park known as Clayton Hill, we have been monitoring bird species during the summer breeding and fall migration seasons to interpret the habitat quality of the areas we are working to restore. Metrics about avian populations provide us with an honest evaluation of the function of our restoration sites because they are not something that we can directly control (as opposed to things like plant species diversity, or forest canopy cover which we actively change through native species plantings). Now, two years into our avian monitoring process our partners at the Western PA Conservancy (WPC) have compiled our first summary report about the bird species that rely on Clayton Hill for fall migration and summer breeding habitat.

To monitor the birds on Clayton Hill, we divided the whole restoration area into four monitoring units (Fig 1). We divided the site this way to control for topographic features such as aspect (north facing vs south facing), elevation (ridge top vs creek bottom), or slope (flat land vs steep hillside) that might inherently attract different bird communities. By monitoring these areas separately, we can also determine if specific units seem to be increasing or decreasing in avian habitat value. In turn, this helps us determine priorities for future restoration efforts.

EBird Sign Scaled
ClaytonHill BirdMonitoring Map Scaled

While it may seem straightforward at first, any ecological monitoring is a time-consuming task. Good data is dependent on repeated sampling, and it can be challenging to acquire the human-capacity required to collect all the information we’d like. Fortunately, through the eBird app we can utilize the observations of volunteer citizen scientists to help monitor the Clayton Hill restoration area. eBird is a product of The Cornell Lab or Ornithology, and it provides a platform that birders everywhere can use to record their bird observations. Partners from the WPC and Carnegie Museum of Natural History’s (CMNH) Powdermill Nature Reserve established ‘eBird hotspots’ for each Clayton Hill restoration unit. By logging bird observation to these eBird hotspots, bird-watching park users are able to perform bird surveys on their own time in our specific monitoring units. These citizen scientists are imperative for the continued monitoring and successful progress of our ecological restoration work.


In 2020 and 2021, researchers and citizen scientists observed 116 species of birds utilizing the Clayton Hill restoration area during the breeding and fall migration seasons (Table 1, below). The Clayton North monitoring unit had the highest species richness (the highest number of unique species observed) in 3 of the 4 monitoring periods (Figure 1). We saw the lowest species richness in the “Nature Trail East” unit, but also had the fewest number of checklists completed in this area (Figure 2). Total bird abundance (the number of individual birds observed) varied across sites and seasons, however survey effort was also inconsistent across seasons, which likely added variance to these early data. For more details, you can view the full report here.


While these data are interesting on their own, the most useful data for evaluating restoration will come from our ability to identify trends over time. These first two years of data are only the baseline numbers that we can use for future comparisons. In the coming years our dataset will grow alongside our restoration plants, and as it does we hope to discover new insights about the changing quality of the Clayton Hill habitat. In the meantime, patience is a requirement. Meaningful restoration occurs on the timescale of years to decades, as it takes plants that long to become established and even longer for them to serve their full suite of ecosystem services. As the native species that we’ve added to Clayton Hill grow, we hope they will provide food and improve habitat for a wide range of bird species. But if we grow it, will they come? Although birds have been observed to show remarkable memory for quality habitat along their migration routes (Mettke-Hofmann and Gwinner. 2003), they first have to discover a site worth remembering. For this reason, it’s important that we’re always looking for opportunities to scale up our restoration efforts and improve connectivity between forest sites.

Already, partners who’ve been working on the Clayton Hill restoration project are using initial observations of avian habitat quality to inform our next management steps. An invasive annual grass called Japanese stiltgrass (Microstegium vimineum) has been steadily expanding through much of Clayton North and Clayton East, and an alarm has been raised that this grass is causing trouble for ground-dwelling migratory songbirds. Given this reality, we are focusing on the habitat needs of those species when designing future projects and workplans – for instance planting shrubs and perennials that will stand up (literally) against the crushing weight of a field of bolting stiltgrass (below).


At Clayton Hill, we are several years into our work facilitating regeneration of native forest habitat but we are still decades away from our goal of achieving a stable, productive, and biodiverse urban forest ecosystem. The presence and abundance of bird species that thrive in healthy native forest communities will keep us honest about our progress, while the tireless work and passion of our many partners keeps us all moving forward in the best ways that we know how. If you’re interested in learning more, we invite you to come out for our fall World Migratory Bird Day event at the Frick Environmental Center on October 8. We also welcome all birders to submit an eBird checklist using our Clayton Hill Hotspots!

This project would not be possible without the joint efforts of the Western Pennsylvania Conservancy, Carnegie Museum of Natural History, Allegheny GoatScape, the Allegheny County Bird Alliance, and the dozens of citizen scientists, volunteers, and donating organizations who’ve contributed to this project. The Clayton Hill Restoration work has been supported by funding from the National Fish and Wildlife Federation, the Pittsburgh Foundation, the PA Department of Conservation and Natural Resources, and donations from Pittsburgh’s park users.

Table 1 (below): Birds species observed on Clayton Hill from 2020-2021. Also reported are the conservation status and population trends of these species as determined by the International Union for Conservation of Nature, and indication of species that are designated of greatest conservation need by the PA State Wildlife Action Plan.   


Species Scientific Name IUCN Conservation Status IUCN Population Trend PA SWAP Greatest need
Acadian Flycatcher Empidonax virescens Least Concern Stable
American Crow Corvus brachyrhynchos Least Concern Increasing
American Goldfinch Spinus tristis Least Concern Increasing
American Redstart Setophaga ruticilla Least Concern Increasing
American Robin Turdus migratorius Least Concern Stable
Baltimore Oriole Icterus galbua Least Concern Stable
Barred Owl Strix varia Least Concern Increasing
Bay-breasted Warbler Setophaga castanea Least Concern Increasing
Black-and-white Warbler Mniotilta varia Least Concern Stable Yes
Black-billed Cuckoo Coccyzus erythropthalmus Least Concern Decreasing
Blackburnian Warbler Setophaga fusca Least Concern Increasing Yes
Black-capped Chickadee Poecile atricapillus Least Concern Increasing
Blackpoll Warbler Setophaga striata Near Threatened Decreasing Yes
Black-throated Blue Warbler Setophaga caerulescens Least Concern Increasing Yes
Black-throated Green Warbler Setophaga virens Least Concern Stable Yes
Blue Jay Cyanocitta cristata Least Concern Stable
Blue-gray Gnatcatcher Polioptila caerulea Least Concern Increasing
Blue-headed Vireo Vireo solitarius Least Concern Increasing
Blue-winged Warbler Vermivora cyanoptera Least Concern Decreasing Yes
Brown Creeper Certhia americana Least Concern Increasing Yes
Brown-headed Cowbird Molothrus ater Least Concern Decreasing
Canada Goose Branta Canadensis Least Concern Increasing
Canada Warbler Cardellina canadensis Least Concern Decreasing Yes
Cape May Warbler Setophaga tigrine Least Concern Increasing
Carolina Chickadee Poecile carolinensis Least Concern Stable
Carolina Wren Thryothorus ludovicianus Least Concern Increasing
Cedar Waxwing Bombycilla cedrorum Least Concern Increasing
Cerulean Warbler Setophaga cerulea Near Threatened Decreasing Yes
Chestnut-sided Warbler Setophaga pensylvanica Least Concern Decreasing
Chimney Swift Chaetura pelagica Vulnerable Decreasing Yes
Chipping Sparrow Spizella passerine Least Concern Decreasing
Common Grackle Quiscalus quiscula Near Threatened Decreasing
Common Nighthawk Chordeiles minor Least Concern Decreasing Yes
Common Raven Corvus corax Least Concern Increasing
Common Yellowthroat Geothylpis trichas Least Concern Decreasing
Connecticut Warbler Oporornis agilis Least Concern Decreasing
Cooper's Hawk Accipiter cooperii Least Concern Increasing
Dark-eyed Junco Junco hyemalis Least Concern Decreasing
Double-crested Cormorant Nannopterum auritus Least Concern Increasing
Downy Woodpecker Dryobates pubescens Least Concern Stable
Eastern Bluebird Silia sialis Least Concern Increasing
Eastern Phoebe Sayornis phoebe Least Concern Increasing
Eastern Towhee Pipilo erythrophthalmus Least Concern Decreasing Yes
Eastern Wood-Pewee Contopus virens Least Concern Decreasing
European Starling Sturnus vulgaris Least Concern Decreasing
Field Sparrow Spizella pusilla Least Concern Decreasing Yes
Fish Crow Corvus ossifragus Least Concern Increasing
Golden-crowned Kinglet Regulus satrapa Least Concern Increasing
Gray Catbird Dumetella carolinensis Least Concern Stable Yes
Gray-cheeked Thrush Catharus minimus Least Concern Decreasing
Great Blue Heron Ardea herodias Least Concern Increasing
Great Crested Flycatcher Myiarchus crinitus Least Concern Stable
Great Horned Owl Bubo virginianus Least Concern Stable
Hairy Woodpecker Leuconotopicus villosus Least Concern Increasing
Hermit Thrush Catharus guttatus Least Concern Stable
Hooded Warbler Setophaga citrina Least Concern Increasing Yes
House Finch Haemorhous mexicanus Least Concern Increasing
House Sparrow Passer domesticus Least Concern Decreasing
House Wren Troglodytes aedon Least Concern Increasing
Indigo Bunting Passerina cyanea Least Concern Decreasing
Kentucky Warbler Geothlypis formosa Least Concern Decreasing Yes
Least Flycatcher Empidonax minimus Least Concern Decreasing
Lincoln's Sparrow Melospiza lencolnii Least Concern Stable
Magnolia Warbler Setophaga magnolia Least Concern Increasing
Mallard Leuconotopicus villosus Least Concern Increasing
Marsh Wren Cistothorus palustris Least Concern Increasing Yes
Merlin Falco columbarius Least Concern Stable
Mourning Dove Zenaida macroura Least Concern Increasing
Mourning Warbler Geothlypis philadelphia Least Concern Decreasing
Nashville Warbler Leiothlypis ruficapilla Least Concern Stable Yes
Northern Cardinal Cardinalis cardinalis Least Concern Stable
Northern Flicker Colaptes auratus Least Concern Decreasing
Northern Mockingbird Mimus polyglottos Least Concern Stable
Northern Parula Setophaga americana Least Concern Increasing
Olive-sided Flycatcher Contopus cooperi Near Threatened Decreasing Yes
Orchard Oriole Icterus spurius Least Concern Stable
Ovenbird Seiurus aurocapilla Least Concern Stable
Palm Warbler Setophaga palmarum Least Concern Increasing
Philadelphia Vireo Vireo philadelphicus Least Concern Increasing
Pileated Woodpecker Hylatomus pileatus Least Concern Increasing
Pine Warbler Setophaga pinus Least Concern Increasing
Purple Finch Haemorhous purpureus Least Concern Decreasing
Red-bellied Woodpecker Melanerpes carolinus Least Concern Increasing
Red-breasted Nuthatch Sitta canadensis Least Concern Increasing
Red-eyed Vireo Vireo olivaceus Least Concern Increasing
Red-shouldered Hawk Buteo lineatus Least Concern Increasing
Red-tailed Hawk Buteo jamaicensis Least Concern Increasing
Red-winged Blackbird Agelaius phoeniceus Least Concern Decreasing
Ring-billed Gull Larus delawarensis Least Concern Increasing
Rock Pigeon Columba livia Least Concern Decreasing
Ruby-crowned Kinglet Regulus calendula Least Concern Increasing
Ruby-throated Hummingbird Archilochus colubris Least Concern Increasing
Scarlet Tanager Piranga olivacea Least Concern Stable Yes
Sharp-shinned Hawk Accipiter striatus Least Concern Increasing Yes
Song Sparrow Melospiza melodia Least Concern Decreasing
Swainson's Thrush Catharus swainsoni Least Concern Stable
Tennessee Warbler Leiothlypis peregrina Least Concern Decreasing
Tree Swallow Tachycineta bicolor Least Concern Stable
Tufted Titmouse Baeolophus bicolor Least Concern Increasing
Turkey Vulture Cathartes aura Least Concern Stable
Veery Catharus fuscescens Least Concern Decreasing
Warbling Vireo Vireo gilvus Least Concern Increasing
White-breasted Nuthatch Sitta carolinensis Least Concern Increasing
White-throated Sparrow Zonotrichia albicollis Least Concern Decreasing Yes
Wild Turkey Meleagri gallopavo Least Concern Increasing
Wilson's Warbler Cardellina pusilla Least Concern Decreasing
Winter Wren Troglodytes hiemalis Least Concern Increasing Yes
Wood Thrush Hylocichla mustelina Least Concern Decreasing Yes
Yellow Warbler Setophaga petechia Least Concern Decreasing
Yellow-bellied Flycatcher Empidonax flaviventris Least Concern Increasing Yes
Yellow-bellied Sapsucker Sphyrapicus varius Least Concern Decreasing
Yellow-billed Cuckoo Coccyzus americanus Least Concern Decreasing
Yellow-rumped Warbler Setophaga coronata Least Concern Unknown
Yellow-throated Vireo Vireo flavifrons Least Concern Increasing
Yellow-throated Warbler Setophaga dominica Least Concern Increasing