Supporting scientific studies, educational opportunities, and protecting the unique Great Marsh in Northern Chester County

Supporting scientific studies, educational opportunities, and protecting the unique Great Marsh in Northern Chester County


2019 Annual Bird Report

2019 Annual Bird Report


Great Marsh Institute (GMI) focuses on the Great Marsh in Chester County, PA.  The Great Marsh is primarily owned by the Moore family and French & Pickering Creeks Conservation Trust. The Great Marsh is a periglacial marsh and the largest marsh in Southeastern Pennsylvania, about 700 acres. Surrounding the marsh is shrub swamps, swamp forests, corridors of floodplain forest, upland forest, row crop farming and the PA turnpike.

The Great Marsh supports a large diversity of flora and fauna.  Over 180 bird species and 160 plant species have been identified on the property. There are also large mammals, such as Whitetail deer, coyote, red and silver fox, muskrat and beaver that are present on the property.  Many species of amphibians and reptiles can also be seen at the Great Marsh.  The Great Marsh also has an IBA (Important Bird Area) designation of D3 from Audubon.  D3: Sites that contain rare or unique habitat or are an exceptional representative of an ecological community type, and that hold important species or species assemblages largely restricted to a distinctive habitat or ecological community type.

This report will focus on the avian community along with the associated activities and initiatives during 2019 and into the future.


2019 was a productive year for birding at GMI. Monthly public bird walks and the bluebird monitoring program greatly increased coverage throughout the year in the easily accessed areas of the property. A total of 133 species were confirmed this past year including the following new species: Glossy Ibis (April 21st), Little Blue Heron (July 28th), Blue Grosbeak (October 6th), Golden Eagle (October 13th), and American Pipit (December 27th). These additions bring the total number of species seen to 183 which ranks 10th for eBird hotspots in Chester County.

The Winter season (Dec-Feb) came in with a count of 49 species. Great Marsh hosts a wintering population of Rusty Blackbirds which are rare in Eastern Pennsylvania. Total populations of Rusty Blackbird have declined 85%-95% in the period between 1970-2010. Great Marsh has the unique habitat necessary to host wintering populations and favored areas include the NW sector of the Catfish pond and adjacent thickets and the wet woodlands south of the Spring pond. Other species of note include: Northern Harrier, Eastern Phoebe (late), Winter Wren, Gray Catbird (late), and American Pipit. A notable absence was a lack of Long-eared Owls of which wintering populations have been recorded annually. Habitat improvement efforts which would involve the planting of either an expanded or new White Pine grove may be needed to sustain this species in the future.

The Spring Migration period (Mar – May) had a total of 119 species reported. Great Marsh is one the most reliable locations to see Blue-winged Teal which is considered rare in Chester County. Starting in April, Virginia Rail and Sora return to the property and begin vocalizing and setting up territories. Wilson’s Snipe also migrate through during this period. There was a sighting of a Long-eared Owl in March in the Pine Grove adjacent to the nature center and it is assumed to be a migrant (see above). American Kestrel was reported for three consecutive weeks from mid-March to the first week in April. Kestrel nest boxes have been installed in two areas and we are hoping that this will lead to a breeding pair on the property. Other spring highlights include: Wild Turkey, Glossy Ibis, Common Raven, Purple Martin, Marsh Wren, Purple Finch, White-crowned Sparrow, Hooded Warble (across Rt 401 on Hillside), and Chestnut-sided Warbler.

The Breeding Period (Jun – Jul) had a total of 66 species recorded. This period needs greater study moving forward as summer vacations and activities limited coverage in 2019. Great Marsh hosts breeding populations of Great Blue and Green Herons and the Great Blue rookery at the lower edge of the marsh (technically not on GMI property) is probably the largest in Chester County. The last week of July saw a post-breeding Little Blue Heron visit the property.

Fall Migration (Aug-Nov) hosted a count of 84 species. A post-breeding Great Egret took up residence during September into the first week of October. An immature Golden Eagle was spotted migrating overhead during the second week of October. This is mainly a Western US species and is very rarely seen east of the Appalachians during migration. November saw good numbers of Fox Sparrow and GMI and is one of the most reliable locations to see this species. A notable absence in October was Lincoln’s Sparrow which more than likely was present but was missed. Rusty Blackbirds returned in good numbers in November for the winter. A Blue Grosbeak was recorded the first week of October.   


Snow Goose (Anser caerulescens)                                                   

Canada Goose (Branta canadensis)                                               

Wood Duck (Aix sponsa)                                                                          

Blue-winged Teal (Spatula discors)                                                 

Northern Shoveler (Spatula clypeata)                                           

American Wigeon (Mareca americana)                                       

Mallard (Anas platyrhynchos)                                                             

American Black Duck (Anas rubripes)                                            

Green-winged Teal (Anas crecca)                                                     

Ring-necked Duck (Aythya collaris)                                                  

Hooded Merganser (Lophodytes cucullatus)                           

Ring-necked Pheasant (Phasianus colchicus)                          

Wild Turkey (Meleagris gallopavo)                                                  

Rock Pigeon (Columba livia)                                                                 

Mourning Dove (Zenaida macroura)                                               

Chimney Swift (Chaetura pelagica)                                                 

Ruby-throated Hummingbird (Archilochus colubris)                      

Virginia Rail (Rallus limicola)                                                               

Sora (Porzana carolina)                                                                           

Killdeer (Charadrius vociferus)                                                          

Least Sandpiper (Calidris minutilla)                                               

Wilson’s Snipe (Gallinago delicata)                                                

Solitary Sandpiper (Tringa solitaria)                                               

Greater Yellowlegs (Tringa melanoleuca)                                  

Ring-billed Gull (Larus delawarensis)                                            

Double-crested Cormorant (Phalacrocorax auritus)                     

Great Blue Heron (Ardea herodias)                                                 

Great Egret (Ardea alba)                              

Little Blue Heron (Egretta caerulea)                                               

Green Heron (Butorides virescens)                                                 

Glossy Ibis (Plegadis falcinellus)                                                       

Black Vulture (Coragyps atratus)                                                      

Turkey Vulture (Cathartes aura)                                                        

Osprey (Pandion haliaetus)                                                                  

Golden Eagle (Aquila chrysaetos)                                                     

Northern Harrier (Circus hudsonius)                                              

Sharp-shinned Hawk (Accipiter striatus)                                     

Cooper’s Hawk (Accipiter cooperii)                                                 

Bald Eagle (Haliaeetus leucocephalus)                                        

Red-shouldered Hawk (Buteo lineatus)                                       

Red-tailed Hawk (Buteo jamaicensis)                                           

Great Horned Owl (Bubo Virginianus)

Long-eared Owl (Asio otus)                                                                   

Belted Kingfisher (Megaceryle alcyon)                                         

Yellow-bellied Sapsucker (Sphyrapicus varius)                                  

Red-bellied Woodpecker (Melanerpes carolinus)                           

Downy Woodpecker (Dryobates pubescens)                           

Hairy Woodpecker (Dryobates villosus)                                      

Pileated Woodpecker (Dryocopus pileatus)                             

Northern Flicker (Colaptes auratus)                                               

American Kestrel (Falco sparverius)                                              

Eastern Wood-Pewee (Contopus virens)                                     

Acadian Flycatcher (Empidonax virescens)                               

Willow Flycatcher (Empidonax traillii)                                          

Eastern Phoebe (Sayornis phoebe)                                                 

Great Crested Flycatcher (Myiarchus crinitus)                                  

Eastern Kingbird (Tyrannus tyrannus)                                           

White-eyed Vireo (Vireo griseus)                                                      

Yellow-throated Vireo (Vireo flavifrons)                                      

Blue-headed Vireo (Vireo solitarius)                                              

Warbling Vireo (Vireo gilvus)                                                               

Red-eyed Vireo (Vireo olivaceus)                                                      

Blue Jay (Cyanocitta cristata)                                                             

American Crow (Corvus brachyrhynchos)                                   

Fish Crow (Corvus ossifragus)                                                              

Common Raven (Corvus corax)                                                           

Carolina Chickadee (Poecile carolinensis)                                

Tufted Titmouse (Baeolophus bicolor)                                          

Northern Rough-winged Swallow (Stelgidopteryx serripennis)                                  

Purple Martin (Progne subis)                                                               

Tree Swallow (Tachycineta bicolor)                                                

Barn Swallow (Hirundo rustica)                                                         

Golden-crowned Kinglet (Regulus satrapa)                               

Ruby-crowned Kinglet (Regulus calendula)                               

White-breasted Nuthatch (Sitta carolinensis)                                   

Blue-gray Gnatcatcher (Polioptila caerulea)                            

House Wren (Troglodytes aedon)                                                     

Winter Wren (Troglodytes hiemalis)                                              

Marsh Wren (Cistothorus palustris)                                               

Carolina Wren (Thryothorus ludovicianus)                                

European Starling (Sturnus vulgaris)                                              

Gray Catbird (Dumetella carolinensis)                                         

Brown Thrasher (Toxostoma rufum)                                               

Northern Mockingbird (Mimus polyglottos)                              

Eastern Bluebird (Sialia sialis)                                                            

Veery (Catharus fuscescens)                                                               

Swainson’s Thrush (Catharus ustulatus)                                     

Wood Thrush (Hylocichla mustelina)                                             

American Robin (Turdus migratorius)                                            

Cedar Waxwing (Bombycilla cedrorum)                                       

American Pipit (Anthus rubescens)                                                 

House Finch (Haemorhous mexicanus)                                        

Purple Finch (Haemorhous purpureus)                                        

American Goldfinch (Spinus tristis)                                                 

Chipping Sparrow (Spizella passerina)                                          

Field Sparrow (Spizella pusilla)                                                          

American Tree Sparrow (Spizelloides arborea)                                  

Fox Sparrow (Passerella iliaca)                                                          

Dark-eyed Junco (Junco hyemalis)                                                   

White-crowned Sparrow (Zonotrichia leucophrys)                         

White-throated Sparrow (Zonotrichia albicollis)                             

Savannah Sparrow (Passerculus sandwichensis)                            

Song Sparrow (Melospiza melodia)                                                 

Swamp Sparrow (Melospiza georgiana)                                       

Eastern Towhee (Pipilo erythrophthalmus)                              

Orchard Oriole (Icterus spurius)                                                        

Baltimore Oriole (Icterus galbula)                                                   

Red-winged Blackbird (Agelaius phoeniceus)                          

Brown-headed Cowbird (Molothrus ater)                                   

Rusty Blackbird (Euphagus carolinus)                                            

Common Grackle (Quiscalus quiscula)                                         

Ovenbird (Seiurus aurocapilla)                                                          

Louisiana Waterthrush (Parkesia motacilla)                           

Northern Waterthrush (Parkesia noveboracensis)                        

Blue-winged Warbler (Vermivora cyanoptera)                                  

Black-and-white Warbler (Mniotilta varia)                         

Common Yellowthroat (Geothlypis trichas)                              

Hooded Warbler (Setophaga citrina)                                             

American Redstart (Setophaga ruticilla)                                     

Cape May Warbler (Setophaga tigrina)                                        

Northern Parula (Setophaga americana)                                    

Magnolia Warbler (Setophaga magnolia)                                   

Yellow Warbler (Setophaga petechia)                                          

Chestnut-sided Warbler (Setophaga pensylvanica)                       

Black-throated Blue Warbler (Setophaga caerulescens)            

Palm Warbler (Setophaga palmarum)                                          

Yellow-rumped Warbler (Setophaga coronata)                                 

Black-throated Green Warbler (Setophaga virens)                         

Scarlet Tanager (Piranga olivacea)                                                  

Northern Cardinal (Cardinalis cardinalis)                                  

Rose-breasted Grosbeak (Pheucticus ludovicianus)                     

Blue Grosbeak (Passerina caerulea)                                              

Indigo Bunting (Passerina cyanea)                                                  


Bird Walks

GMI hosted public bird walks in each month of the year. Scores of visitors were able to enjoy GMI’s unique habitat and avian diversity. This is a program is effective at promoting GMI’s mission. This program was started in 2018 and we are looking forward to continuing it in the future.

Bluebird Trail

In March 2019, volunteers gathered and helped construct and place 12 Bluebird nest boxes around the property to create Great Marsh Institute’s Bluebird trail.  The trail was registered with Project NestWatch, which was created by Cornell Lab of Ornithology.  NestWatch is a nationwide monitoring program designed to track status and trends in the reproductive biology of birds, including when nesting occurs, number of eggs laid, how many eggs hatch, and how many hatchlings survive. The database is intended to be used to study the current condition of breeding bird populations and how they may be changing over time as a result of climate change, habitat degradation and loss, expansion of urban areas, and the introduction of non-native plants and animals. To become a certified Nestwatch monitor, volunteers must read and review Cornell’s nest box monitoring guide and pass a test to register.


The Motus Wildlife Tracking System is an international collaborative research network that uses a coordinated automated radio telemetry array to track the movement and behaviour of small flying animals. Motus is used to track birds, bats, and large insects affixed with digitally-encoded radio transmitters that broadcast signals several times each minute. These signals are detected by receiving stations that scan for signals 24 hours a day, 7 days a week, 365 days a year, depending on the site. When results from many stations are combined, the array can track animals across a diversity of landscapes covering thousands of kilometers.

GMI hosts a MOTUS antenna and Jim Moore has been instrumental in testing and developing the associated technologies. Results can be found here:

American Kestrel Nest Boxes

Two nest boxes were installed in 2019 to attract breeding American Kestrels to the property. GMI has appropriate habitat and it is hopped that these installations will be successful in 2020.

Acoustic Monitoring

We began experimenting with acoustic monitoring systems in the marsh in 2019. GMI was in possession of a Wildlife Acoustics SM-4 recording device as well as an AudioMoth acoustic logger. Deployments were made in various locations and programed to produce audio recordings at predetermined times throughout the day. Results were analyzed using Wildlife Acoustics Kaleidoscope software which produced sonograms that were then reviewed to detect various species vocalizations. In late 2019 we launched a fundraiser that enabled us to purchased five AudioMoth devices that will be deployed in set locations in the marsh in 2020.  


Acoustic Monitoring

With the purchase of additional monitoring devices, there will be a focus on a better understanding the presence and distribution of species in the more remote areas of Great Marsh. A total of six devices are available for deployment starting in April and lasting into May. Some of the target species include known inhabitants such as Virginia Rail, Sora, American Bittern, and Common Gallinule and efforts to detect yet to be recorded species such as King Rail, Least Bittern and Black Rail. While there is no guarantee that the yet to be recorded species will be present, there is appropriate habitat that suggests they are possible. The installation of remote recording devices enables us to record data in some of the remote areas of the marsh on a daily basis.

Purple Martin Houses

Purple Martins have been recorded at Great Marsh in migration periods. The lack of appropriate nesting sites may limit their ability to gain residence during the breeding season. Purple Martins readily accept martin homes and GMI has appropriate habitat to support their presence.

Chimney Swift Tower

The Chimney Swift population has been in rapid decline over the last few decades. These swifts utilize man-made industrial and residential chimneys for roosting and nesting. As industry has changed and more residential chimneys are capped, habitat is rapidly disappearing for this species. Audubon has building plans posted for Chimney Swift towers that this species will readily take to. GMI’s upland open areas can provide a resource to help stabilize their decline.

Long-eared Owl Habitat Improvement

Wintering Long-eared Owls have been present at Great Marsh since at least the 1990’s. The Long-eared Owl population has been showing signs of decline in recent years most likely due to the degradation of the White Pine plantation which is their preferred habitat in this area. This is a species which is considered rare in Chester County and efforts should be made to provide a successional habitat. Ideally a new planting of White Pines of significant size (5 Ft. range) over an area of at least the current pine grove area should be sufficient to ensure the continuation of this rare species at GMI. With that being said, this will require a potentially significant financial investment and a need for fundraising and/or grant money.  

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