60 birds were recorded seen in Pennsylvania in September in our iNaturalist sample; 6 of the top 50 are at their peak this month. The list is ranked by number of research-grade observations.
Top birds in September

Great Blue Heron

Mourning Dove

Red-tailed Hawk

Blue Jay
Common Yellowthroat
Gray Catbird

Mallard

Great Egret

House Sparrow

Ruby-throated Hummingbird

Northern Cardinal

American Goldfinch
All birds seen in Pennsylvania in September
| # | Species | Scientific name | Family | Obs. | Peak in state |
|---|---|---|---|---|---|
| 1 | Great Blue Heron | Ardea herodias | Herons, Egrets, and Bitterns | 1,492 | Aug (past peak) |
| 2 | Mourning Dove | Zenaida macroura | Pigeons and Doves | 905 | Apr (past peak) |
| 3 | Red-tailed Hawk | Buteo jamaicensis | Hawks, Eagles, and Kites | 900 | Oct (rising) |
| 4 | Blue Jay | Cyanocitta cristata | Crows, Jays, and Magpies | 843 | May (past peak) |
| 5 | Common Yellowthroat | Geothlypis trichas | New World Warblers | 819 | May (past peak) |
| 6 | Gray Catbird | Dumetella carolinensis | Mockingbirds and Thrashers | 755 | May (past peak) |
| 7 | Mallard | Anas platyrhynchos | Ducks, Geese, and Swans | 739 | Apr (past peak) |
| 8 | Great Egret | Ardea alba | Herons, Egrets, and Bitterns | 728 | Aug (past peak) |
| 9 | House Sparrow | Passer domesticus | Old World Sparrows | 694 | Apr (past peak) |
| 10 | Ruby-throated Hummingbird | Archilochus colubris | Hummingbirds | 684 | Aug (past peak) |
| 11 | Northern Cardinal | Cardinalis cardinalis | Cardinals and Allies | 683 | Apr (past peak) |
| 12 | American Goldfinch | Spinus tristis | Finches, Euphonias, and Allies | 670 | Aug (past peak) |
| 13 | Canada Goose | Branta canadensis | Ducks, Geese, and Swans | 644 | Apr (past peak) |
| 14 | Double-crested Cormorant | Nannopterum auritum | Cormorants and Shags | 551 | Apr (past peak) |
| 15 | Wild Turkey | Meleagris gallopavo | Pheasants, Grouse, and Allies | 509 | Apr (past peak) |
| 16 | Turkey Vulture | Cathartes aura | New World Vultures | 508 | Apr (past peak) |
| 17 | American Robin | Turdus migratorius | Thrushes | 505 | Apr (past peak) |
| 18 | Magnolia Warbler | Setophaga magnolia | New World Warblers | 446 | Sep (peak) |
| 19 | Bald Eagle | Haliaeetus leucocephalus | Hawks, Eagles, and Kites | 434 | Apr (past peak) |
| 20 | Black-and-white Warbler | Mniotilta varia | New World Warblers | 422 | May (past peak) |
| 21 | Downy Woodpecker | Dryobates pubescens | Woodpeckers | 419 | Apr (past peak) |
| 22 | American Redstart | Setophaga ruticilla | New World Warblers | 418 | May (past peak) |
| 23 | Northern Flicker | Colaptes auratus | Woodpeckers | 406 | Apr (past peak) |
| 24 | Red-bellied Woodpecker | Melanerpes carolinus | Woodpeckers | 405 | Apr (past peak) |
| 25 | Ovenbird | Seiurus aurocapilla | New World Warblers | 385 | May (past peak) |
| 26 | Green Heron | Butorides virescens | Herons, Egrets, and Bitterns | 376 | Aug (past peak) |
| 27 | Black-throated Green Warbler | Setophaga virens | New World Warblers | 354 | Sep (peak) |
| 28 | Song Sparrow | Melospiza melodia | New World Sparrows | 352 | Apr (past peak) |
| 29 | Northern Parula | Setophaga americana | New World Warblers | 352 | Sep (peak) |
| 30 | Cape May Warbler | Setophaga tigrina | New World Warblers | 351 | Sep (peak) |
| 31 | House Finch | Haemorhous mexicanus | Finches, Euphonias, and Allies | 348 | Apr (past peak) |
| 32 | Eastern Phoebe | Sayornis phoebe | Tyrant Flycatchers | 342 | Apr (past peak) |
| 33 | Cooper's Hawk | Astur cooperii | Hawks, Eagles, and Kites | 336 | Jan (past peak) |
| 34 | Osprey | Pandion haliaetus | Ospreys | 331 | Aug (past peak) |
| 35 | European Starling | Sturnus vulgaris | Starlings | 326 | May (past peak) |
| 36 | Red-eyed Vireo | Vireo olivaceus | Vireos, Shrike-Babblers, and Erpornis | 326 | May (past peak) |
| 37 | White-breasted Nuthatch | Sitta carolinensis | Nuthatches | 301 | Apr (past peak) |
| 38 | Carolina Wren | Thryothorus ludovicianus | Wrens | 295 | Apr (past peak) |
| 39 | Eastern Bluebird | Sialia sialis | Thrushes | 287 | Apr (past peak) |
| 40 | Eastern Wood-Pewee | Contopus virens | Tyrant Flycatchers | 268 | Sep (peak) |
| 41 | Wood Duck | Aix sponsa | Ducks, Geese, and Swans | 227 | Apr (past peak) |
| 42 | Black-throated Blue Warbler | Setophaga caerulescens | New World Warblers | 227 | May (past peak) |
| 43 | Tennessee Warbler | Leiothlypis peregrina | New World Warblers | 222 | Sep (peak) |
| 44 | Tufted Titmouse | Baeolophus bicolor | Tits, Chickadees, and Titmice | 216 | Apr (past peak) |
| 45 | Northern Mockingbird | Mimus polyglottos | Mockingbirds and Thrashers | 216 | Apr (past peak) |
| 46 | Cedar Waxwing | Bombycilla cedrorum | Waxwings | 209 | May (past peak) |
| 47 | Pileated Woodpecker | Dryocopus pileatus | Woodpeckers | 198 | May (past peak) |
| 48 | Bay-breasted Warbler | Setophaga castanea | New World Warblers | 186 | May (past peak) |
| 49 | Ring-billed Gull | Larus delawarensis | Gulls, Terns, and Skimmers | 180 | Feb (past peak) |
| 50 | Chipping Sparrow | Spizella passerina | New World Sparrows | 177 | Apr (past peak) |