Evolutionary Breakthrough of Hawks and Eagles (Accipitridae)

Binomial nomenclature is the primary system that scientists use to name, group, and differentiate organisms in the tree of life. Occasionally, new data is collected that causes scientists to reconsider and refine these hypotheses, and names must be changed to reflect the current state of knowledge.

Hawks, eagles, and some vultures are classified in the family Accipitridae. Many of the species in this group are charismatic and well known to the public, but there is lingering uncertainty about their evolutionary relationships. A recent paper published in the Biological Journal of the Linnean Society, co-authored by Dr. Matthew Halley (Assistant Curator of Birds at Delaware Museum of Nature and Science) with lead author Dr. Therese Catanach (Academy of Natural Sciences of Drexel University) and Dr. Stacy Pirro (Iridian Genomes), sheds new light on this evolutionary puzzle. By analyzing genetic (DNA) sequences from 237 species, they propose a major revision to the taxonomy of Accipitridae, which will require several name changes.

This family tree shows the currently accepted grouping of various hawk species.

For local birders, the most intriguing finding is the non-monophyly of the cosmopolitan genus Accipiter. To resolve this issue, Catanach et al. propose to reclassify the American Goshawk (Accipiter atricapillus) and Cooper’s hawk (Accipiter cooperii) in the genus Astur.

This Cooper’s Hawk skeleton on exhibit in the museum may need a new title soon.

Catanach, T. A., Halley, M. R., and S. Pirro. 2024. Enigmas no longer: using Ultraconserved Elements to place several unusual hawk taxa and address the non-monophyly of the genus Accipiter (Accipitriformes: Accipitridae). Biological Journal of the Linnaean Society, blae028. https://doi.org/10.1093/biolinnean/blae028

If you are unable to access the paper and would like a copy, please email Dr. Halley.

Learn more about Dr. Halley’s research projects and publications on his website.

Bird Department Launches “Carcass Club”

The DelMNS Bird Department has recently started a “carcass club” with wildlife ecology and environmental science student volunteers from the University of Delaware. In the group, students facilitate the preparation of new specimens for the scientific collection. Ever since its inception, the museum has salvaged “window-strikes” and other recently-deceased birds, to save their bodies for scientific use.

Once a week, the club gathers at the museum to prepare study skins (a specialized form of taxidermy) and spread wings for the collections, while also receiving training from the collections staff. Students will have the opportunity to learn other preparation types, such as skeletons, later in the year. Specimens vouchered in the museum are an important resource for monitoring the long-term health of local ecosystems, and researchers from around the world will have access to these specimens and their data.

Study skins are used for morphometrics (measuring and analyzing the shape and size of specimens), biodiversity, and genetics research in addition to identification.

It’s a messy job, but someone has to do it!

Wooden dowels provide structural support prevent specimens from flattening, and make them easier to handle.

Morphometrics including the lengths of wings, tails and beaks are measured before and after a specimen is prepared.

Great Pine Swamp, 200 Years Later


In May 1811, the Scottish-born American ornithologist, Alexander Wilson (1766-1813), collected specimens of three supposedly new wood warbler species, and one new thrush in a place called the “Great Pine Swamp.” Twenty years later, John James Audubon (1785-1851) claimed that he “followed [Wilson’s] track” in 1829 and located the swamp near Rockport, Pennsylvania.

However, in June 2023, Dr. Matthew Halley, Assistant Curator of Birds, used historical maps to retrace Wilson’s expedition and found that the “Great Pine Swamp” was actually in Monroe County, PA, 16 miles east of Rockport and on the opposite side of the Lehigh River, contrary to Audubon’s claim. This resolves the mystery surrounding the swamp’s location and offers new insights into Wilson’s and Audubon’s observations of the species there.

The “A” on this map shows the likely field site of Audubon. The “W” is the actual collecting location of Wilson’s “Great Pine Swamp,” on the opposite side of the Lehigh River, courtesy of Matthew R. Halley.

The paper is free and open access. Read here.

Learn more about Halley’s research projects and publications on his website.

New species discovered using museum’s online collection data

Introducing Bourciera ovata

In the summer of 2020 — the first year of the pandemic — a team of European scientists began compiling a checklist of known terrestrial and fresh water mollusks of mainland Ecuador. The effort included occurrences recorded in past scientific reports or literature, museum datasets available online, and verified observations from citizen science projects like iNaturalist.

In reviewing our records, one of the scientists, Marijn Roosen of the Natural History Museum of Rotterdam, noticed some unusual records of a unique land snail in the Andes Mountains. Marijn requested more information about the snails and photographs to confirm their identifications. It turned out that some of the specimens from Puyo, Ecuador represented species previously unknown to researchers, including the newly-named Bourciera ovata.

With high resolution photographs of different aspects of the snail’s shell, Marijn was able to describe it as a new species, demonstrating a greater diversity of Ecuadorian land snails and the importance of having museum collection data accessible, as surely there are many more new species to be discovered. The research was published in September in the journal Folia Malacologica.

DMNH 151926, formerly thought to be Bourciera fraseri, is now the type specimen for the newly-discovered species Bourciera ovata. A type specimen is the specific specimen on which a new species is based. The museum’s mollusk collection already included around 1,200 type specimens. Photos by Alex Kittle.

Roosen, M. and Dorado, C. Revision of the genus Bourciera Pfeiffer, 1852 (Gastropoda: Helicinidae), with the description of six new species from Ecuador and Peru. Folia Malacologica, 30(3), 155–167. https://doi.org/10.12657/folmal.030.018

Taxonomy changes reflected in new specimen organization

The introduction of Bourciera ovata is just one example of how what scientists know about species and their taxonomy continues to develop. While working from home during the pandemic in 2020, Collections Manager Alex Kittle began reorganizing the mollusk collection based on updated information and species names, and later moved the actual specimens to reflect these changes. Information about our entire mollusk collection is now publicly available on the Symbiota portal, InvertEBase. Our collection profile shows 233,603 records are available online, representing 500 families and 15,658 species; 32% are georeferenced to specific locations.

Collection Manager of Mollusks Alex Kittle in the DelMNS scientific collections.

MOTUS detects Lesser Yellowlegs

A bird species that migrates through our area — a Lesser Yellowlegs (Tringa flavipes) — was detected by the Motus Wildlife Tracking System (MOTUS) tower on the museum’s roof, installed by University of Delaware scientists in early 2021 to track movement of Purple Martins (Progne subis).

Lesser Yellowlegs © U.S. Fish and Wildlife Service Northeast Region

MOTUS is an international collaborative research network dedicated to tracking the migration of small birds, made possible by radio telemetry towers, which read the transmitter tags carried by birds that fly within about 15 km of the tower. Since our tower was installed, it has logged more than 3,200 readings.

The MOTUS tower was installed in early 2021.

The vast majority of detections are of banded Purple Martins, with some individual birds detected many times. The tower has also detected a few American Kestrels (Falco sparverius).

The tower detected the Lesser Yellowlegs on July 13, 2022. According to Dr. Nicholas Bayly, it had been banded in late April near Cali, Colombia, by researchers associated with Audubon Colombia and Asociación Selva, a non-profit organization supporting research and conservation in the Neotropics (selva.org.co).

After it was banded, the bird flew north and was detected by three towers in Missouri, and one in Michigan, before heading to our area. Five other MOTUS towers in our region also detected the bird, including Longwood Gardens. Dr. Matthew Halley, the museum’s Interim Curator of Birds, says the detection highlights the value of projects like the MOTUS program, which enable scientists all over the world to collaborate on migratory research.

This map shows the flight path of the Lesser Yellowlegs detected near DelMNS.

Map data © 2022 Google, INEGI Imagery © 2022 NASA

Research Headquarters

How we know what we know:

In the Research Headquarters, sponsored by DuPont, explore stories about scientific research and related projects from our local area and beyond.

Scientists help us better understand the world around us. They conduct research in all kinds of environments: in the field, in the laboratory, and even in the museum’s natural history collections. They observe animals and plants in the air, on the land, and in the water. They conduct experiments and collect data to test their observations. Over time, they draw conclusions based on what they find, helping us make sense of what’s happening on the planet. What we know changes as scientists gather and share new information.

Tucked into the Regional Journey Gallery, the Research Headquarters currently includes stories about the Delaware Shorebird Project and the juvenile humpback whale collected by museum scientists in 2018. Other stories currently on view also include some of the research behind DuPont’s Kalrez® technology, citizen science project Coast Snap by Delaware Sea Grant, and exploring with carnivore ecologist Rae Wynn-Grant, courtesy of the IF/THEN® Collection.

On the back end, the stories in the Research Headquarters are installed in a content management system created by digital design studio RLMG. It’s set up so new stories can be uploaded seasonally.

Stories involving museum scientists

The juvenile humpback whale skull was weighed on its way to the museum.

A tale of a whale

A juvenile humpback whale died at sea and washed ashore near Port Mahon, Delaware. The whale, one of 34 humpback whales stranded on the East Coast in 2017, presented an opportunity to tell this important story at the Delaware Museum of Nature & Science. But first, museum staff had to determine how to retrieve the 280 lbs. skull from the beach.

Shorebirds at Mispillion Harbor.

Shorebirds on the bay

Each spring millions of horseshoe crabs migrate into Delaware Bay to lay their eggs on sandy beaches. At the same time, nearly half a million shorebirds arrive to rest and refuel on their way to breed on the Arctic Tundra. Their primary food is horseshoe crab eggs. The Delaware Shorebird Project studies the birds and the importance of the bay to their survival. Learn more about the Delaware Shorebird Project.

Stories from our partners

DuPont’s Kalrez® technology

From aerospace and chemical processing to chip manufacturing and oil and gas applications, DuPont™ Kalrez® elastomers are engineered to provide more stability, more resistance, and more effective sealing. Learn more about this technology from DuPont scientists. Learn more about Kalrez®. 

Coast Snap by Delaware Sea Grant

To manage coastlines, we need to understand how they behave. Delaware Sea Grant’s CoastSnap is a citizen science program harnessing smartphones and orthophotogrammetry to help scientists learn more about the shoreline. By using CoastSnap, the community becomes an integral part of the science team. Learn more about CoastSnap.

From the IF/THEN® Collection

Image by Tsalani Lassiter, courtesy of the IF/THEN® Collection

Carnivore ecologist Rae Wynn-Grant, courtesy of the IF/THEN® Collection

Rae Wynn-Grant, Ph.D. might just have the coolest job on the planet. As a carnivore ecologist working for National Geographic, she researches how endangered species are impacted by human interaction. Her work currently focuses on grizzly bears in Montana, but has previously taken her around the world — including to Tanzania and Kenya to study lions. The If/Then Collection is a digital asset library of women STEM innovators. Learn more about the If/Then® Collection.

The Research Headquarters is sponsored by DuPont

Up on the roof: How flying a kite is part of bird research

Though researchers have studied of bird migration in general, the ability to track the journey of small-bodied birds has remained a mystery for years. Motus Wildlife Tracking System is an international collaborative research network dedicated to tracking the migration of small birds. The tracking of the birds is made possible by radio telemetry towers which read tags from animals passing nearby. Motus is dedicated to involving numerous locations in tracking a wide variety of small animals locally, regionally, and even internationally, describing their research as “the ultimate hands-on community science project.”

The museum is participating in this community project with a radio telemetry tower installed in January 2021 on our roof with the help of graduate student Katie Bird, University of Delaware professor Jeff Buler, Ph.D., community scientist ​Steve Cotrell, and Ian Stewart of the Delaware Nature Society. The project is funded by the Delaware Audubon Society and Delaware Ornithological Society.

Katie is conducting research in Dr. Buler’s lab at the University of Delaware’s Department of Entomology and Wildlife Ecology focusing on Purple Martins (Progne subis), and she worked tirelessly to get her equipment ready before the Purple Martins return in April.

Dr. Jean Woods, former curator of birds, helped Katie prepare for their return through regular visits to our roof to perform system updates on our tower. The tower consists of an antenna, a receiver which records the data, and a solar panel which powers the entire thing. The tower can record the compatible tags of any birds that pass by within a range of 10 miles. The radio tags used are solar powered and tiny (0.5 grams), so they can remain on the bird for its entire life and acquire the data without having to recapture the bird. Once the data is recorded, it is automatically made available to researchers. This data is what Katie will use to study the movements of Purple Martins in the early spring as they return to their colonies.

This map shows where the local Motus towers are that Katie is using for research, including London Grove TownshipBucktoe Creek PreserveLongwood Gardens, DMNH, and the Delaware Nature Society’s DuPont Environmental Education Center.

While she awaits the return of the Purple Martins, Katie has collected data in various ways to train the receiver’s algorithm. She previously used a drone to replicate the flight of small birds, but the drone is out of commission. Katie then came up with the idea of using a kite to simulate the flight of a tagged martin. By flying a kite on our roof, Katie collected both GPS and radio data similar to the data the LifeTags will provide to the receiver.

Kite flying, algorithms, and — most importantly — patience are the main ingredients in Katie’s recipe for successful Purple Martin migration research. We will be watching closely for the return of the Purple Martins, and the data our tower collects as they fly through Delaware.