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State of Delaware

Blue Hen Chicken

Birding Delaware

Delaware is 96 miles long and ranges from 9 to 35 miles across, totaling 1,954 square miles and making it the second-smallest state in the United States after Rhode Island. Delaware 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 12 miles (19 km) 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. This border extends all the way east to the low-tide mark on the New Jersey shore, then continues south along the shoreline until it again reaches the twelve-mile arc in the south; then the boundary continues in a more conventional way in the middle of the main channel (thalweg) of the Delaware River Estuary. To the west, a portion of the arc extends past the easternmost edge of Maryland. The remaining western border runs slightly east of due south from its intersection with the arc. The Wedge of land between the northwest part of the arc and the Maryland border was claimed by both Delaware and Pennsylvania until 1921, when Delaware's claim was confirmed.

Delaware is subdivided into three counties: from north to south, New Castle, Kent County and Sussex.

Delaware is on a level plain; the highest elevation, located at Ebright Azimuth, near Concord High School, Wilmington, does not rise fully 450 feet above sea level. The northern part is associated with the Appalachian Piedmont and is full of hills with rolling surfaces. 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.

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 (roughly 100 miles from its northernmost to southernmost points), 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 of the State. The transitional climate of Delaware supports a surprising variety of vegetation. At Trap Pond State Park in Sussex County, bald cypress grow -- 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.



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Number of Species

Number of bird species: 417

As of July 2015


iGoTerra Checklist

iGoTerra Checklist

Fatbirder Associate iGoTerra offers the most comprehensive and up to date birds lists on the web

Useful Reading

Birding the Delaware Valley Region

A Comprehensive Guide to Birdwatching in Southeastern Pennsylvania, Central and Southern New Jersey and North Central Delaware John J Harding 233 pages Temple University Press 1980

ISBN: 0877221820

Buy this book from NHBS.com

Birds of Delaware

(Pitt Series in Nature and Natural History) Gene K. Hess (Editor); Richard L. West, Maurice V. Barhill, l Fleming Hardcover - 750 pages (August 1998) University of Pittsburgh Press

ISBN: 0822940698

Buy this book from NHBS.com

Useful Information

State Bird

Blue Hen Chicken


Delaware Audubon Society


Incorporated in 1977, the Delaware Audubon Society, Inc., 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 environmental protection and conservation.

Delaware Nature Society


Founded in 1964, the Delaware Nature Society, a private, non-profit membership organization, fosters understanding, appreciation, and enjoyment of the natural world through education; preserves ecologically significant areas; and advocates stewardship and conservation of natural resources.

Delaware Records Committee


The records committee is charged with maintaining the Delaware State List of Bird Species, which consists of all bird species accepted as having been observed in Delaware. They also maintain the Delaware Review List, which are those birds for which the committee requests documentation from the observer…

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…

DelMarVa Ornithological Society


The Delmarva peninsula comprises the state of Delaware and portions of Maryland and Virginia. Delmarva is characterized by the rolling hills of the piedmont to the north and the flat coastal plain to the south. Thousands of square miles of wetlands ring the peninsula, which is surrounded by the Delaware Bay, Chesapeake Bay, and Atlantic Ocean…

Nature Conservancy in Delaware


Another greatly improved NC site - check out the stunning picture on the opening page! Known as the small wonder, Delaware has a remarkable natural heritage that includes dense forests, fresh and salt-water marshes, intertidal mud flats, and over 200 miles of coastal shoreline. Today, this land, along with its wealth of biological diversity, is ours to work, enjoy, and pass on to future generations…


Abbreviations Key

Bombay Hook NWR


Satellite 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.

Fish & Wildlife Service - Delaware


Locations of reserves etc.

Wetlands - Delaware Bay


A major estuarine system lying at the border of the Appalachian Piedmont physiographic province to the west, and the Atlantic Coastal Plain province…

Forums & Mailing Lists


Mailing List

To post to list: marvadel@yahoogroups.com

List contact: marvadel-owner@yahoogroups.com

To subscribe to list: marvadel-subscribe@yahoogroups.com

Mailing List – Discussion Group - MARVADEL is an electronic discussion group for 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.

Guides & Tour Operators

Click on WAND for tours, guides, lodges and more…

Birding Pal


Local birders willing to show visiting birders around their area…

Trip Reports

Click on WAND for tours, guides, lodges and more…


Trip Report Repository

CloudBirders was created by a group of Belgian world birding enthusiasts and went live on 21st of March 2013. They provide a large and growing database of birding trip reports, complemented with extensive search, voting and statistical features.

2010 [09 September] - Hans-Åke Gustavsson & Kristian Svensson - Cape May & Delaware

Report PDF

…This trip report contains the bird observations made during a visit to mainly the Cape May area in New Jersey in September 2010. As we both consider ourselves as regulars at Falsterbo, one of the top sites for watching diurnal migration of raptors and passerines in Europe, we wanted to get the experience of visiting one of the counterpart localities on the other side of the Atlantic Ocean. The trip was therefore focused on seeing as many birds as possible, especially wood warblers, during peak migration time..

2012 [09 September] - Louise Zemaitis - Cape May & Bombay Hook

Report PDF

…By the end of the day we had tallied 14 species including many Black-and-white Warblers, American Redstarts, and Northern Parulas. Particularly superb views were had of Cape May and Black- throated Green warblers in the trees near Lily Lake, and eye level Bay-breasted and Blackburnian warblers at Cape May Point State Park. Warblers were our constant companions throughout the day as we looked to the sky for hawks, the Delaware Bay for gulls and terns, and everywhere else for Monarchs. By afternoon, we found ourselves in a river of Monarchs in Cape May Point…

2012 [10 October] - Louise Zemaitis - Cape May & Bombay

Report PDF

…Fall migration is driven by weather. Birders’ conversations inevitably turn to the weather’s relativity to yesterday, today, or tomorrow’s birding. When will the cold front arrive? Will the winds hold from the northwest? Gosh, I hope that it doesn’t rain. Our tour began with fog. Yes, fog in September. Quite unusual, but it set the scene for a wonderful week in Cape May and Bombay Hook. For each morning’s fog brought very little rain, mild temperatures, and fine afternoons. Oh, and unpredictably good birding!…

2013 [09 September] - Mattias Ullman - Cape May, Delaware & Jamaica Bay

PDF Report

...The trip was deliberately put early in the season, partly because waders were one of our main priorities. Still, we were lucky to get two days with plenty of wood warblers in Cape May, due to cold winds from northwest...


Delaware Museum of Natural History


The bird collection consists of approximately 67,000 study skins, 9,000 skeletons, 6,000 alcohol-preserved birds, and 36,000 clutches of eggs. The holdings represent about 4,000 bird species. About 140 taxa are in the type collection. The alcohol collection was eighth in the world in 1982 (Wood et al. 1982) and has nearly doubled in size since then, the skeleton collection was 18th in the world in 1986 (Wood & Schnell 1986); and the egg collection is second largest in North America (Kiff & Hough 1985)…

Other Links

Birding in Delaware


Thanks to its strategically ideal location along major waterways in the heart of the Mid-Atlantic region, Delaware is not only a convenient and picturesque destination for millions of East Coast travelers, it is revered around the world as a center for watching the thousands of rare songbirds, shorebirds and raptors that live in and migrate through the Delmarva Peninsula.

Birding the Delaware Valley Region


The Delaware Valley is the name given to the region that lays on either side of the Delaware River, centered on Philadelphia. This consists of southeastern Pennsylvania, central and southern New Jersey and the state of Delaware…

Delaware Birding Locations - IBAs


This is a list of places to go birding in and near Delaware. I have described the best birding locations and given directions for finding the sites. I also have placed a Delaware checklist on a separate page, and the checklist contains suggestions of places to look for many of the species. I have had help from other birders and have acknowledged that help in the text.

Delaware Birding Trail


In a first of its kind collaboration, Delaware Audubon, Delmarva Ornithological Society, the Delaware Department of Natural Resources and Environmental Control and the U.S. Fish & Wildlife Service have joined talents to create the Delaware Birding Trail.

Delaware Birds


Recent Postings from Dalaware birding

Delmarva Birding


Sightings and adventures in birding on the Delmarva Peninsula…

Shorebirds Crisis


Many shorebirds are long distance migrants that complete trips between their wintering and breeding grounds in stages. Rather than stopping and feeding frequently during their journeys, they fly directly between a few widely separated stopover areas where they feed for extended periods. Given an abundant food source, shorebirds have the ability to quickly store the fat they need to fuel their long distance flights. The stopover areas provide seasonally abundant food sources that are critical for the next leg of their trips. Stored fat may also be needed to survive once they reach their breeding grounds. Many shorebirds breed in the artic or sub-artic and arrive before it has warmed enough for food to be available. Under these conditions, shorebirds must continue to live off their fat reserves for the first part of the short artic breeding season.