State of Delaware

Black-necked Stilt Himantopus mexicanus ©Frank Schulenburg Website

Delaware is c.150km (95 miles) long and ranges from 15km to 50km (9 to 35 miles) across, totalling just under 6,500 KM² (2,500 square miles) and making it the second-smallest state in the United States after Rhode Island. It is bounded to the north by Pennsylvania; to the east by the Delaware River, Delaware Bay, New Jersey and the Atlantic Ocean; and to the west and south by Maryland. Small portions of Delaware are also situated on the far, or eastern, side of the Delaware River estuary, sharing land boundaries with New Jersey. The state of Delaware, together with the Eastern Shore counties of Maryland and two counties of Virginia, form the Delmarva Peninsula, which stretches south down the Mid-Atlantic Coast.

The definition of the northern boundary of the state is highly unusual. Most of the boundary between Delaware and Pennsylvania is defined by an arc extending 19 km (12 miles) from the cupola of the courthouse in New Castle. It is referred to as the Twelve-Mile Circle. This is the only true-arc political boundary in the United States. Delaware is subdivided into three counties: from north to south, New Castle, Kent and Sussex. Delaware’s most populous city is Wilmington, and the state’s capital is Dover, the second most populous. The state’s population is just over one million people.

Delaware is on a level plain, the lowest mean elevation of any US state; the highest elevation, located at Ebright Azimuth, near Concord High School, Wilmington, does not rise fully 140m (450 feet) above sea level. The northern part is associated with the Appalachian Piedmont and is full of rolling hills. South of Newark and Wilmington, the state follows the Atlantic Coastal Plain with flat, sandy, and, in some parts, swampy ground. A ridge about 75 to 80 feet in altitude extends along the western boundary of the state and is the drainage divide between the two major water bodies of the Delaware River and several streams flowing into Chesapeake Bay in the west.

Blackbird State Forest – ©Delaware Forest Service CC BY-SA 4.0 via Wikimedia Commons

Since almost all of Delaware is a part of the Atlantic Coastal Plain, the climate is moderated by the effects of the ocean. The state is somewhat of a transitional zone between a humid subtropical climate and a continental climate. Despite its small size there is significant variation in mean temperature and amount of snowfall between Sussex County and New Castle County. The southern portion of the state has a somewhat milder climate and a longer growing season than the northern portion. The transitional climate of Delaware supports a surprising variety of vegetation. At Trap Pond State Park in Sussex County, bald cypress grows — this is thought to be one of the northernmost stands of such trees.

The vegetation in New Castle County, on the other hand, is more typical of that of the northeastern United States. All parts of Delaware have relatively hot, humid summers. While Sussex and Kent Counties are considered to fall in the humid subtropical climate zone, there is some debate about whether northern New Castle County falls in the humid subtropical climate zone or warm continental climate.

Birding Delaware

Delaware Bay and Atlantic Ocean shores offer some prime birding habitat. Two well-known wildfowl refuges; Bombay Hook and Prime Hook along its western edge offer a wide range of wildfowl and waders, gulls and terns. Cape Henlopen State Park with views over the bay is a migration hot spot, with hawk-watching in Autumn being particularly good. Middle Run Natural Area is good for passerines with breeding woodpeckers, flycatchers, warblers, buntings and orioles. Brandywine Creek State Park is also good for breeding birds and migration.

Brandywine Creek – ©Ad Meskens, CC BY-SA 3.0 via Wikimedia Commons

Away from the coast the hills on the state’s northwestern border have birds typical of the north with a number of species at their most northern range too.

Delaware Birding Trail

Despite its small size, Delaware encompasses six well-defined ecological regions. The Delaware Birding Trail takes in all of them, showing their contrasts and providing an education in ecology even as it entertains with great birding. Many of the trail’s 27 sites are along the coastline, where beaches, tidal flats, and marshes offer an exciting diversity of birds year-round. Pale little piping plovers nest on the beaches, joined in spring and fall by busy flocks of other plovers and sandpipers, while migrating black terns, yellowlegs, stilts, and rails gather in the marshes. In winter great flocks of snow geese and ducks shelter in these same wetlands, and their thundering flights at dawn are reason enough for a cold-weather visit. If you can tear yourself away from the coast, Delaware’s interior has stunning meadows and forests with their own treasures. The low hills along the state’s northwestern edge contain songbirds typical of more northerly climes, like the soft-voiced veery and the sharply patterned blue-winged warbler. Southern tier pine flats are enlivened by gangs of spunky little brown-headed nuthatches, which reach the northernmost edge of their range here – Kenn Kaufman

  • Additional Material - Kenn Kaufman

Number of Species
  • Number of bird species: 427

    (As at March 2024)

    State Bird - Blue Hen Chicken

  • Avibase - Bird Checklists of the World

    PDF Checklist
    This checklist includes all bird species found in Delaware , based on the best information available at this time. It is based on a wide variety of sources that I collated over many years.
  • Delaware Bird Records Committee

    PDF Checklist
    The Delaware State List of Bird Species contains the following 427 species of birds that have been accepted for Delaware by the Delaware Bird Records Committee (DBRC) as of February 2023.
  • Wikipedia

    List of birds of Delaware
Useful Reading

  • A Field Guide to the Mid-Atlantic Coast

    | Including the Jersey Shore, Cape May, Delaware Bay, the Delmarva Peninsula, and the Outer Banks | By Patrick J Lynch | Yale UP | 2021 | Flexibound | 434 pages, 721 colour photos, colour illustrations and colour maps | ISBN: 780300246469 Buy this book from
  • Birding the Delaware Valley Region

    | (A Comprehensive Guide to Birdwatching in Southeastern Pennsylvania, Central and Southern New Jersey and North Central Delaware) | By John J Harding & Justin J Harding | 1980 | Temple University Press | 233 pages, site maps | Out of Print | ISBN: 9780877221821 Buy this book from
  • Birds of Delaware

    | By Gene K Hess, Richard L West, Maurice V Barnhill & Lorraine M Fleming | University of Pittsburgh Press | 1998 | Hardback | 655 pages, Illustrations, figures, tables, maps | Out of Print | ISBN: 9780822940692 Buy this book from
  • Birds of Delaware

    | By Marc Parnell | Naturalist & Traveler Press | 2022 | Paperback | 312 pages, colour photos | ISBN: 9781954228399 Buy this book from
  • Birds of Maryland & Delaware Field Guide

    | (includes Washington, D.C. & Chesapeake Bay) | by Stan Tekiela | Adventure Publications | 2023 | Edition 2 | Paperback | 392 pages, colour illustrations | ISBN: 9781647553708 Buy this book from
  • Birds of Maryland, Delaware, and the District of Columbia

    | By Bruce M Beehler | Johns Hopkins University Press | 2019 | Hardback | 504 pages, 684 colour photos, 2 maps | ISBN: 9781421427331 Buy this book from
  • Delaware Birds: A Folding Pocket Guide to Familiar Species

    | By James R Kavanagh & Raymond Leung | Waterford Press | 2003 | Unbound | 12 pages, colour illustrations | ISBN: 9781583552223 Buy this book from
Museums & Universities
  • Delaware Museum of Natural History

    The bird collection consists of approximately 67,000 study skins, 11,000 skeletons, and 36,000 clutches of eggs. We also maintain a small tissue collection containing samples from eastern North American taxa. The collection, worldwide in scope, has especially strong collections of Philippine and Central and South American birds. The holdings represent about 4,000 bird species. About 140 taxa are in the type collection. Extinct species are also represented. Formation of the collection began when the Museum was founded in 1957. Among the collections that can be found here are those of George Miksch Sutton, Allan R. Phillips, Olin S. Pettingill, T.D. Burleigh, D.S. Rabor, M. Hachisuka, Vivien Hewitt, and Sibley’s Yale-Peabody Expedition. We also maintain an archive that contains field notes and other documentation from some of these collectors.
  • Delaware Audubon Society

    ncorporated in 1977, the Delaware Audubon Society is a statewide chapter of the National Audubon Society. Delaware Audubon is dedicated to developing a better appreciation of our natural environment and working for species and habitat conservation.
  • Delaware Nature Society

    Delaware Nature Society’s mission is to connect people with the natural world to improve our environment through education, advocacy and conservation. We envision a healthy and sustainable environment. We envision a healthy and sustainable environment. Our mission is to connect people with the natural world to improve our environment through education, advocacy, and conservation.
  • Delaware Ornithological Society

    Dedicated to enjoying, protecting and studying Delaware's bird life
  • Delaware Records Committee

    The Delaware Bird Records Committee is charged with maintaining the Delaware State List of Bird Species (Downloadable PDF) (updated September 2018), which consists of all bird species accepted as having been observed in Delaware. A subset of this list is the Delaware State Review List, which are extremely rare species for which the committee requests documentation from observers to document their presence in the state.
  • Delaware Shorebird Monitoring Program

    The purpose of the Annual Reports is to provide an account of shorebird monitoring work that has been conducted on the Delaware side of Delaware Bay. It is intended to provide a popular account of activities
  • Nature Conservancy in Delaware

    The Nature Conservancy in Delaware works with government agencies, private corporations, conservation organizations and our members to conserve the places on which people and wildlife depend. This has resulted in the conservation of more than 30,000 acres across Delaware since 1990.
  • The Sussex Bird Club

    Spread the word! Prime Hook NWR offers free bird walks on the first Saturday of each month (Feb-May 2024). Our club provides the leaders for these walks.

Abbreviations Key

  • *List of Delaware state wildlife areas

    InformationSatellite View
    The state wildlife system includes over 56,000 acres of public land set aside to conserve Delaware's fish and wildlife populations. Unlike Delaware's state parks, which are geared to more general outdoor recreation, the wildlife and conservation areas are managed primarily for recreational activities such as hunting, fishing, and birding, similar to the National Wildlife Refuges operated by the U.S. Fish and Wildlife Service.
  • Delaware National Estuarine Research Reserve

    InformationSatellite View
    Freshwater wetlands, ponds and forest lands dominate the Blackbird Creek componentThe St. Jones component is dominated by salt marsh and open water habitats of the Delaware Bay.
  • Fish & Wildlife Service - Delaware

    WebsiteSatellite View
    Locations of reserves etc.
  • IBA Delaware Bay Wetlands

    WebsiteSatellite View
    The Delaware Bay's shores are a critical stopover area for six species of migrating birds. The late May arrival of these birds coincides with the spawning of horseshoe crabs, producing one of the most dramatic natural phenomena anywhere in the world. Feeding on crab eggs, the birds refuel and continue their journey to Arctic breeding grounds. Unfortunately, there has been a dramatic decline in horeshoe crab numbers since 1991 and a corresponding decline in shorebird numbers.
  • IBA Great Cypress Swamp Conservation Area

    WebpageSatellite View
    The Great Cypress Swamp is one of the largest contiguous areas of forest on the Delmarva Peninsula. Located at the headwaters of the Pocomoke River, the swamp has 600ha in Worcester Co., Maryland and 4400 ha in Sussex Co., Delaware. This IBA also includes the floodplain forests flanking the Pocomoke River south of the swamp to Highway 50. The swamp, once dominated by Atlantic white cedar and bald cypress, is now dominated by seasonally flooded forest of loblolly and pond pine and hardwoods, including red maple, sweetgum, black tupelo and black gum. Wood Thrush, Prothonotary Warbler, Swainson?s Warbler, Kentucky Warbler and Prothonotary Warblers
  • NR Great Marsh Preserve

    WebpageSatellite View
    Stretching out over 17,000 acres between Lewes Beach and Slaughter Beach, the Great Marsh Preserve is an immense coastal wetland located along Delaware Bay. With its diverse ecology and its variety of wildlife, the Great Marsh Preserve provides an awe-inspiring glimpse of nature...
  • NR Little Creek Wildlife Area

    WebpageSatellite View
    The wildlife area consists of over 4,700 acres of natural area consisting of tidal marsh, forest and agricultural fields dedicated to wildlife management.
  • NWA Prime Hook

    WebpageSatellite View
    The refuge is an important stopover site for migratory birds as they travel up and down the Atlantic Flyway and provides protected breeding habitat for federally and State-listed threatened and endangered species, as well as many neo-tropical migrating bird species. Prime Hook’s habitat features include salt marsh, freshwater marsh, ponds and impoundments, wooded swamps and upland grasslands and forest. Hundreds of native plant and animal species thrive in this mosaic of these diverse cover types that provide habitat for 308 species of birds, 51 species of fish, 45 species of reptiles and amphibians, 37 species of mammals, and an array of rare insect and plant species.
  • NWR Bombay Hook

    WebpageSatellite View
    Bombay Hook NWR, located on the western shore of Delaware Bay 8 miles southeast of Smyrna, Delaware, was established in 1937 to provide habitat for migratory waterfowl. Objectives have since broadened to include other migratory birds, a diversity of other native wildlife species and wildlife-oriented public use.
  • SP White Clay Creek State Park

    WebpageSatellite View
    The land that is today known as White Clay Creek State Park includes parts of the boundary line made famous by Mason and Dixon, who began their historic survey at “a post mark’d west,” a location that lies within the park. Over 37 miles of trails lead explorers to historic sites and scenic vistas overlooking lush valleys and impressive rock outcrops. Hikers and mountain bikers enjoy the large number of easy-to-moderate trails throughout the park. Of special interest are those at Possum Hill and the Judge Morris Estate, along with the Pomeroy Rail-Trail, which runs alongside White Clay Creek.
  • WA Assawoman

    InformationSatellite View
    Assawoman Wildlife Area is a state wildlife area located in Sussex County, Delaware located near Frankfort, Delaware and Little Assawoman Bay. It is made up of three large tracts of land that total 3,100 acres (1,300 ha) that were originally former farms that were lost due to the Great Depression, and managed by the Delaware Department of Natural Resources and Environmental Control (DNREC).
  • WA Cedar Swamp

    InformationSatellite View
    Cedar Swamp Wildlife Area is a state wildlife area located in New Castle County, Delaware, along shore of the Delaware Bay. It is 5,515 acres (2,232 ha) in size and is managed by Delaware Department of Natural Resources and Environmental Control (DNREC), Division of Fish & Wildlife
Sightings, News & Forums
  • ABA Delaware Bird News

    News by date
  • Delaware Birding

    Forum, News etc.
    Please use discretion if posting locations of rare, endangered, or sensitive species, especially nesting species. Posts with sensitive information may be removed at the discretion of the administrators.
  • Delaware Ornithological Society

    Sightings Database
    Almost 300,000 records of birds in Delaware dating back to 1794
  • E-Bird Delaware Rare Bird Alert

    The reports show observations of rare birds in Delaware. Includes both unreviewed and reviewed/approved observations.birders of all descriptions in Maryland, Virginia, Delaware and surrounding areas. The group will concentrate on local birding issues and events, such asinteresting sightings, advice on local birding hotspots, announcements of local bird club meetings, events and exhibitions, planning of days out and joint birding expeditions, etc. MARVADEL is open to all individuals with a sense of humor and an interest in wild birds in the mid-Atlantic region.
  • Kent County Rare Bird Alert

    The report below shows observations of rare birds in Kent County. Includes both unreviewed and reviewed/approved observations.
Guides & Tour Operators
  • Delmarva Birding Weekends

    The Delmarva Peninsula possesses an extensive variety of environments, including barrier islands, tidal wetlands, cypress swamps, upland fields and primeval forests. Our annual Delmarva Birding Weekends celebrate the amazing warblers, shorebirds, waterfowl and raptors that visit and live here on the peninsula...
Trip Reports
  • 2019 [05 May] - Sunrise Birding

    PDF Report
    Sunrise Birding’s inaugural tour to the Delaware Bay was indeed a shorebird spectacular featuring thousands of migrating shorebirds feeding on the beaches and viewed at close range. We witnessed Horseshoe Crabs coming ashore to lay eggs and learned about this important food source for many of these migrating birds. The cold, wet spring weather seemed to hamper the progression of the Red Knots, but we did have times where we saw more than 12,000 Semipalmated Sandpipers in one place and thousands of Ruddy Turnstones, Dunlin, Short-billed Dowitchers and others. In addition to prime shoreline habitats, we visited several other sites including two outstanding National Wildlife Refuges - Bombay Hook and Prime Hook NWR. With the help of some local expert birders, we found most of what we were looking for and enjoyed good food, camaraderie and great birding! We look forward to doing it again next year!
  • DOS Trip Reports

    ...The second monthly Peterson Refuge walk for 2024 was joined by 18 hardy observers plus two accompanying parents and included several newcomers to birding...
Other Links
  • Birding the Delaware Valley Region

    For those of us who live in the Delaware Valley Region and for those who are visiting this wonderful area, here is ALL THE BIRDING INFORMATION that you need to know in order to bird within a 75-mile radius of Philadelphia, with emphasis on the counties surrounding Philadelphia.
  • Delaware Birding Trail

    The creation of the Delaware Birding Trail was a one and a half year collaborative effort by Delaware Audubon, Delmarva Ornithological Society, the Delaware Department of Natural Resources and Environmental Control and the U.S. Fish & Wildlife Service. Its purpose is to educate, inform and encourage both instate and out of state birders to experience the wealth of birdlife Delaware has to offer.
  • Delmarva Birding

    The Delmarva Peninsula possesses an extensive variety of environments, including barrier islands, tidal wetlands, cypress swamps, upland fields and primeval forests. Our annual Delmarva Birding Weekends celebrate the amazing warblers, shorebirds, waterfowl and raptors that visit and live here on the peninsula.
Photographers & Artists
  • Delaware Bird Photography

    Facebook Page
    Delaware Bird Photography is a group for people to share photographs they have taken of wild Delaware birds. Feel free to post questions about equipment, methods, and strategy in photographing birds.

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