A bird is silhouetted against a dark blue sky. A bird holds an insect in its beak while perching on the branch of a tree. The bird and branches are in shadow showing as solid black against the sky.
Where Marsh Meets Forest A bird holds a tasty snack while perching in a tree at Delaware's Milford Neck Preserve. © John Hinkson / TNC

Stories in Delaware

Delaware's Melodic Migration

A study at TNC’s Milford Neck Preserve aims to quantify the Delaware Bay's significance as a stopover for migratory songbirds.

Just a few hundred yards inland from the gentle waves lapping at the shore of the Delaware Bay, loblolly pines grow in the sandy soils next to the salt marsh at The Nature Conservancy’s Milford Neck Preserve. This spot, where the tidal wetlands meet the coastal forest, is the perfect place to study migratory songbirds that stop to feed and rest during their long annual migrations each spring and fall.

Aerial view of the interface between open water and wetlands and a coastal forest. The water cuts meandering channels before ending at the green forested land.
Where Wetlands and Forest Meet Aerial view at Milford Neck Preserve. DSU graduate student Aya Pickett has been conducting research in this area to quantify the habitat benefits for migratory songbirds. © John Hinkson / TNC; Flight support provided by Light Hawk

Quantifying the Bayshore's Significance for Birds

Aya Pickett, a graduate student at Delaware State University (DSU), sets up a net to catch the birds among the thorny greenbrier, bayberry bushes and American holly trees. Pickett is working with Dr. Christopher M. Heckscher, Professor of Environmental Science at DSU, on a study to better quantify the importance of the Delaware Bayshore in the lifecycle of neotropical migratory songbirds. The study was funded by NOAA’s Delaware Sea Grant Program administered by the University of Delaware.

“Boreal migrants are of conservation concern considering their recent population declines and the threats they face on their breeding grounds and migratory stopover sites—like the Delaware Bayshore—between boreal and tropical forests,” says Dr. Heckscher. “To the best of my knowledge, this is the first research project aimed at studying migratory songbird use of Delaware Bay coastal marshes—in New Jersey or Delaware—since 1993 and the first concerted banding effort.”

Looking through a pair of binoculars. A hand holds a pair of black binoculars looking out over an open wetland.
Birding Hot Spot An estimated 70.4 million people get outside to watch birds one or more times per year. © Lily Mullock/TNC

In addition to collecting important data on migratory birds, this study also aims to assess how sea level rise could impact the behaviors of bird watchers and other outdoor enthusiasts who visit coastal Delaware. 

Birders flock to the Delaware Bayshore to witness the migrations of shorebirds and songbirds that move along the coast with the changing of the seasons, contributing to tourism revenue for coastal communities. Once complete, data from this economic study will be used to help policymakers understand current recreational behavior of bird watchers and other recreationists and how coastal public lands tourism could change under future sea-level rise scenarios.

Catch, Record, Band and Release

Despite the onset of the pandemic in the spring of 2020, a plan was made to safely proceed with the data collection in the field during the spring migration.

An array of supplies are laid out on a table. A tackle style box with tiered compartments holds small vials for blood, tags and labels, film cannisters with metal bands and a small pair of pliers
A woman kneels on the ground gently freeing a small bird from a long thin net that has been strung between trees to catch birds for a banding project.
Close view of two hands holding a dark colored bird.
A small bird with greenish black feathers, a black face, gray cap and yellow breast is held by the feet by a scientist.
A person holds a ruler against a small black and white bird, taking its measurements.
A small bird with a bright yellow breast and face, black throat and cap and greenish brown wings.
A woman holds a small bird while standing at a table under an open sided tent. Another women standing across from her records notes.
A person holds a small gray bird and uses a ruler to take its measurements.
A small yellow bird with greenish brown wings and a dark gray cap stares quizzically at the camera.
Three white cloth sacks hang pinned from a line. In the background under an open sided tent two women record observations for a bird banding study.

Birds are safely captured in a mist net and then identified, aged, sexed, weighed and measured by Pickett. Each bird is assigned a standardized muscle and fat score. Before release, a USGS numbered leg-band is affixed to each bird for future identification. Pickett and Dr. Heckscher have the required federal and state permits to capture and study these birds.

Pickett’s subjective observations will be just as important as the data analysis. Behavioral observations will be used to corroborate the results: frequent observations of birds actively refueling will suggest important use of stopover sites while infrequent or rare such observations will suggest light or non-significant use of resources. After another year of observations and data collection in 2021, Dr. Heckscher will assess the importance of barrier islands, marsh hummocks and nearby woodlands to migratory birds using a variety of quantitative and qualitative means.

The Delaware Bayshore: Critical for Birds of All Kinds

Neotropical migratory birds breed in North America—usually the northern U.S. and Canada—during the spring and summer months. Then, during the fall and winter in the northern hemisphere, the birds fly thousands of miles south to Central America, South America or the Caribbean. 

Nearly 200 species in North America are considered neotropical migrants, occurring in every habitat and representing 14 different families and subfamilies ranging from songbirds—like thrushes, tanagers and warblers—to shorebirds, some raptors and a few types of waterfowl. 

The food sources that neotropical migratory birds rely on to feed their young, such as flying insects, caterpillars, fruits and nectar, are found in abundance in the northern hemisphere during our spring and summer months. But these food sources are not sufficiently available through the cold winter, hence the need to fly south for warmer locales.

Many neotropical migratory songbirds are experiencing long-term population declines, says Dr. Heckscher. He explains that while a variety of causes have been investigated, habitat loss on breeding, wintering and migratory stopover grounds are the primary culprits. 

One primary cause of habitat loss is climate change, as rising sea levels are squeezing coastal habitats. Low-lying coastal ecosystems such as saltmarshes and barrier islands are particularly vulnerable. Loss or degradation of coastal habitats can have direct effects on songbirds as these habitats are critical for resting, cover and refueling en route to breeding and non-breeding grounds.

“The Delaware Estuary lies along the Mid-Atlantic flyway—a major migratory corridor for both north and southbound transient birds including waterfowl, waders, raptors, shorebirds and songbirds,” says Dr. Heckscher. 

The immense concentrations of waterfowl and shorebirds that depend on the estuary’s barrier islands and near-shore habitats are well known, and these migration events draw spectators from around the world resulting in a significant positive effect on Delaware’s local economies.

A study in the 1990s involving several private landowners, along with state and federal agencies, quantified the use of Delaware Bayshore coastal habitats by southbound migratory songbirds. The study found that the Bayshore barrier islands and marsh hummocks are an internationally important coastal resource supporting critical habitat for millions of migratory songbirds. 

Surprisingly, no subsequent study has been undertaken to further investigate the ecological importance of near-shore habitats to songbirds, nor has any substantial attention since focused on this landscape. Dr. Heckscher says he’s unaware of any action taken to manage or protect barrier islands and near-shore habitats specifically for songbirds.

A small bird with white streaked gray wings, yellow throat and a greenish head is held by a person prior to being banded as part of a scientific study.
Northern Parula (Setophaga americana). A northern parula caught for banding by graduate student Aya Pickett during the Fall 2020 migration at Milford Neck Preserve. © Aya Pickett
× A small bird with white streaked gray wings, yellow throat and a greenish head is held by a person prior to being banded as part of a scientific study.
A wide open stretch of beach ends at a shoreline edged with seaweed. The sun reflects on the calm surface of the Delaware Bay. In the foreground the words, Milford Neck, have been written in the sand.
Milford Neck Preserve The sun shines on the Delaware Bay at TNC's Milford Neck Preserve one of the First State’s most spectacular natural areas. © John Hinkson / TNC
× A wide open stretch of beach ends at a shoreline edged with seaweed. The sun reflects on the calm surface of the Delaware Bay. In the foreground the words, Milford Neck, have been written in the sand.
Northern Parula (Setophaga americana). A northern parula caught for banding by graduate student Aya Pickett during the Fall 2020 migration at Milford Neck Preserve. © Aya Pickett
Milford Neck Preserve The sun shines on the Delaware Bay at TNC's Milford Neck Preserve one of the First State’s most spectacular natural areas. © John Hinkson / TNC

The study being overseen by Dr. Heckscher will provide data about the ability of the site at Milford Neck Preserve to provide critical food during the spring and fall migrations, and thus the ecological importance of these habitats. Data will be gathered by assessing the physical condition of birds observed and caught by Pickett at the observation station on the edge of the marsh.

“Milford Neck has the largest remaining contiguous coastal forestland along the Delaware Bayshore,” says TNC Land Steward Natasha Whetzel. TNC owns 2,800 acres at Milford Neck, and along with the State of Delaware and Delaware Wild Lands Inc., has collectively protected 10,000 acres and nearly 10 miles of mostly-undeveloped beaches, wetlands and coastal forests.

“We know that these protected lands are important for migratory birds—that’s for sure,” says Whetzel. “We’re thrilled that DSU chose to partner with us on this study. It will help us better understand the significance of Milford Neck in this huge global bird migration that happens each spring and fall.”

A small black and white striped bird with a white throat is held by a person prior to be banded as part of a scientific study.
Black and White Warbler (Mniotilta varia) caught for banding by graduate student Aya Pickett during the Fall 2020 migration at Milford Neck Preserve. © Aya Pickett
× A small black and white striped bird with a white throat is held by a person prior to be banded as part of a scientific study.
A hand tightly grips the feet of a small falcon. The bird has bright black eyes and brown and white mottled feathers.
Merlin Falcon (Falco columbarius) caught at Milford Neck Preserve in 2021 during a research study examining habitat use by neotropical migratory songbirds. © Aya Pickett
× A hand tightly grips the feet of a small falcon. The bird has bright black eyes and brown and white mottled feathers.
Black and White Warbler (Mniotilta varia) caught for banding by graduate student Aya Pickett during the Fall 2020 migration at Milford Neck Preserve. © Aya Pickett
Merlin Falcon (Falco columbarius) caught at Milford Neck Preserve in 2021 during a research study examining habitat use by neotropical migratory songbirds. © Aya Pickett

Economic Welfare Effects of Sea-level Rise on Coastal Recreation in Delaware

The economic portion of the study is being led by Dr. Sonja Kolstoe, a former Assistant Professor of Economics at Salisbury University and now a Research Economist for the USDA Forest Service. 

Dr. Kolstoe is working on the project with her undergraduate research assistant Kelsey Poisal of Salisbury University. They are studying the economic effects of sea-level rise on coastal recreation—to include bird watching—in Delaware. Sea-level rise is already altering coastal recreational opportunities in Delaware due to more frequent and prolonged flooding events.

The results of the study can be used to help policymakers understand current recreational behavior to coastal public lands and how that behavior will likely change in the future. 

They collected survey data from people in the region to understand coastal public lands visitation for recreational activities like birding, hunting, boating and fishing. Environmental goods and services provide society with ecosystem services (e.g. carbon storage, storm protection, recreational opportunities, etc.) which are not typically bought and sold in a market, hence the term nonmarket.

A person floats in a kayak in a flat, wide body of water. They are silhouetted against the sky and seem to hover in the distance at the horizon.
Nature's Benefits Coastal public lands provide both economic and recreational value. © © Daniel White

“To make informed policy decisions about coastal public lands, we need to understand the benefits derived from them, to include the nonmarket benefits” says Dr. Kolstoe. “Travel behavior allows us to measure one part of the total economic value of coastal public lands: the use value for recreation.” 

This study will inform end-users, like government and nonprofits, about how economic welfare for visitors to coastal public lands is predicted to change with sea-level rise. This will help decisionmakers make a more informed decision about managing coastal public lands in the future based on sea-level rise forecasts.

A smiling woman holds a small bird by its feet. The bird has greenish black wings, black face, gray cap and yellow breast.
Migratory Songbirds Aya Pickett holds a Common yellowthroat (Geothlypis trichas) banded as part of a study of the lifecycle of neotropical migratory songbirds. © Louis Mason / Louis Mason Photography
× A smiling woman holds a small bird by its feet. The bird has greenish black wings, black face, gray cap and yellow breast.
Two women stand across from each other with a long folding table between them. The table holds a number of materials and supplies needed for a bird banding project.
Collecting Data Aya Pickett (l) and Amanda Crandall (r) prepare supplies and materials during a bird banding effort at Delaware's Milford Neck Preserve. Spring 2021. © Louis Mason
× Two women stand across from each other with a long folding table between them. The table holds a number of materials and supplies needed for a bird banding project.
Migratory Songbirds Aya Pickett holds a Common yellowthroat (Geothlypis trichas) banded as part of a study of the lifecycle of neotropical migratory songbirds. © Louis Mason / Louis Mason Photography
Collecting Data Aya Pickett (l) and Amanda Crandall (r) prepare supplies and materials during a bird banding effort at Delaware's Milford Neck Preserve. Spring 2021. © Louis Mason

Planning for the Future

As Pickett prepares for another year of observing, catching and banding birds at the Milford Neck Preserve in 2021, she wonders if she will re-catch any of the same birds that she banded last year.

“The most common species I caught were myrtle warbler, common yellowthroat and gray catbird,” said Pickett after the fall 2020 migration. “Of all the birds that we captured, my favorites are always the warblers. They are beautiful to look at and can also accomplish some amazing physical feats with their migrations.”

Some of the more colorful birds that were caught at Milford Neck in 2020 include the Northern parula, Indigo bunting, Black and white warbler, Hooded warbler, Wilson’s warbler, Magnolia warbler and the American redstart

A small bird with a bright yellow breast and face, black throat and cap and greenish brown wings.
Hooded Warbler (Setophaga cintrina) caught for banding during the Spring 2021 migration. © Aya Pickett

Some of these species, like the Wilson’s warbler whose population is in steep decline, stop in Delaware to refuel on their way to or from breeding grounds in Canada. Other birds like the American redstart and the Hooded warbler may spend the summer here along the Delaware Bayshore, laying eggs and raising their young before heading south in the fall.

In one seven-year study in Pennsylvania, approximately 50% of banded male Hooded warblers returned to the same area to breed again. Is the same true for similar neotropical migratory songbirds that breed in Delaware? This research project will help get us one step closer to finding out. 

Coastal communities will benefit from this research as well—and not just the birders. After completion of the studies, a workshop with stakeholders will take place to present findings and discuss protection and restoration needs. The information will be available for use by academics, nonprofits and government agencies to help plan future land protection efforts and make the best use of places that have already been protected.

“This study is providing the ornithological world with important data collected for the first time,” says Dr. Heckscher. “Soon we will have a clear picture of the Bayshore’s place in the global migrations of millions of songbirds. We’re eager to see what we learn in 2021—it’s exciting to be part of a multi-faceted study. This partnership with Delaware State University, Salisbury University, the USDA Forest Service, Delaware Sea Grant and The Nature Conservancy is a great example of people from different sectors working together for the benefit of people and wildlife. And there’s no better subject to bring people together than birds."

A wide flat channel of water curves through low green wetlands. A tall clump of trees stands out against the horizon in the background.
Milford Neck Preserve View of the marsh at the preserve along the Delaware Bay. June 2020. © John Hinkson / TNC

See For Yourself: Birdwatching Guide

Are you interested in catching a glimpse at these colorful, transient birds during their migrations? The best time to view these migratory songbirds along the Delaware Bayshore is from May to early June and then again in September and early October. 

While TNC’s Milford Neck Preserve is not publicly accessible, we highly recommend visiting the nearby Prime Hook National Wildlife Refuge located about 10 miles south of Milford Neck. Prime Hook is approximately a 30-minute drive north of Lewes and Rehoboth Beach.

Bombay Hook National Wildlife Refuge, located northeast of Dover, is a birder’s paradise year-round. It offers several elevated platforms for bird watching that are great for spotting migratory songbirds that spend lots of time among the treetops. Numerous other public lands along the Delaware Bayshore—especially those to the east of Route 9—offer remarkable settings for bird watching and soaking up nature.

Visitors to TNC’s Edward H. McCabe Preserve and the Ponders Tract at Pemberton Forest Preserve will also see some of these birds during the migrations. These preserves are both located several miles inland from the Delaware Bay, so the birds will not be present in the same numbers that you will see closer to the coast. TNC’s public preserves in Delaware are free to visit—another great reason to get out there and enjoy nature.

This study is in progress and is primarily funded through a Delaware Sea Grant and also supported in part by the USDA Forest Service. The views expressed within the article are those of the author and researchers who are involved in this study and they should not be construed to represent any official USDA or U.S. Government determination or policy.