New bird species discovered through scientific collections

Natural history collections are full of surprises, with scientists updating what is known about different species and uncovering new ones.

Dr. Matthew Halley, Assistant Curator of Birds, is the lead author of a recently-published paper that splits the Slaty-backed Nightingale-Thrush (Catharus fuscater) into seven different species and four subspecies — including a newly-described species from eastern Panamá: the Darién Nightingale-thrush (Catharus arcanus).

Photo of Matthew Halley by Jenna McCullough

These genetically distinct populations live in secluded mountain rainforests in Central and South America and began to diverge from each other nearly three million years ago.

The species look very similar to an untrained eye. To document their differences, Dr. Halley and his team sequenced DNA from multiple populations, studied physical features like plumage color, iris color and bill color, and analyzed differences in their vocalizations.

Dr. Halley shared the findings on his Twitter (now X) account. Read on for a summary, along with some of the figures from the paper:

This figure shows the geographic distribution of the C. [fuscater] complex in Central and South America. Lines point to type localities. The variation in shapes denote sampling locations for different molecular data. Shape size is correlated with the number of samples (1–3).

The C. fuscater complex (Turdidae) is composed of several disjunct populations that inhabit cloudy mountain rainforests, ranging from Costa Rica to Bolivia. These birds are diabolically shy and more often heard than seen. Their song is a series of sweet, musical whistles.

The research identified 10 genetically distinct populations that have been evolving independently for multiple glacial cycles. Molecular clock suggests most lineages diverged in early Pleistocene / late Pliocene— ancient lineages with independent evolutionary trajectories.

This figure shows taxonomic variation in the structure of ‘punctuation calls’, visualized in RavenPro 1.5 (Cornell University), recognizing three groups based on shared acoustic structure: (Type 1) pulsed/rippling: C. [f.] hellmayri, Undescribed 1 (now C. arcanus), C. [f.] mirabilis; (Type 2) long/sinuous: C. [f.] sanctaemartae, C. [f.] fuscater, C. [f.] berplepschi; (Type 3) short/simple: Undescribed 2 (now C. o. tenebris), C. [f.] opertaneus, Undescribed 3 (now C. b. nebulus), C. [f.] mentalis.

Populations were divergent in the acoustic structure of three different call types, which are presumed to be innately acquired (i.e., not learned), and there were subtle differences among populations in song structure, which is presumably learned.

This image is a side view of polychromatic adult plumages in C. [f.] mentalis (from left to right): 1, FMNH 433742, a ‘grey’ male with enlarged testes; 2, FMNH 433738, a ‘brown’ male with enlarged testes; 3, FMNH 364458, a ‘brown’ male with testes not enlarged; 4, FMNH 433740, an adult female with an enlarged ovary. Adults of both colour types (FMNH 433742, 433738) were collected at the same site in November
2001.

Halley traveled to the American Museum of Natural History, the National Museum of Natural History and Carnegie Museum of Natural History to study their C. fuscater specimens, and borrowed specimens from the Field Museum, LSU Museum of Natural Science, and the Academy of Natural Sciences of Drexel University, bringing them to the museum to look at sexual and age-related differences in plumage color.

This image shows ventral and dorsal views of the adult male plumages in C. b. berlepschi, C. b. caniceps, C. o. tenebris ssp. nov., C. b. nebulus ssp. nov., and C. mentalis.

With a large sample of study skins assembled under one light source (flat panel LED), subtle differences between populations, difficult to appreciate in the field, became easier to notice — Halley scored this variation by comparing the specimens to published color standards.

The taxonomic revision splits the C. [fuscater] complex into seven species, of which one is newly described, and four subspecies, of which two are newly described (C. opertaneus tenebris, C. berlepschi nebulus). New English names were proposed for each species. The seven species are:

Talamanca Nightingale-thrush (Catharus hellmayri) – monotypic – Northern mountains of Costa Rica (Rincón de la Vieja, Miravalles, Tenorio) to west-central Panama (Parque Nacional Santa Fé, Veraguas). (Photo: alchetron.com)
Darién Nightingale-thrush (Catharus arcanus, sp. nov.) – monotypic – E Panama, endemic to Serranía de Majé and Serranía del Darién, from Cerro Azul in the west, to Cerro Tacarcuna in the east
Pirre Nightingale-thrush (Catharus mirabilis) – monotypic – Endemic to Cerro Pirre, Darién province, E Panama. (Photo: ML 242929041)
Cordilleran Nightingale-thrush (Catharus fuscater) – polytypic – (1) C. f. sanctaemartae, endemic to Sierra Nevada de Santa Marta, NE Colombia; (2) C. f. fuscater, Sierra de Perijá of Venezuela, N and E Andes of Colombia and Venezuela. (Photo: ML 206115721)
Trans-Andean Nightingale-thrush (Catharus berlepschi) – polytypic – (1) C. b. berlepschi, W Andes in Ecuador; (2) C. b. caniceps, W Andes in Ecuador, S to NW Peru; (3) C. b. nebulus, ssp. nov., E Peruvian Andes. (Photo: ML 38468741)
Antioquia Nightingale-thrush (Catharus opertaneus) – polytypic – (1) C. o. opertaneus, NW and Central Andes in Colombia, S to Napo, Ecuador; (2) C. o. tenebris, ssp. nov., Río Chinchipe watershed of N Peru and SE Ecuador
Cochabamba Nightingale-thrush (Catharus mentalis) – monotypic – S Peru, east of the Río Apurímac, E to Santa Cruz, Bolivia

Note: Monotypic species are not divided into subspecies. Polytypic species can be divided into at least two subspecies.

Halley, M. R., Catanach, T. A., Klicka, J., and J. D. Weckstein. 2023. Integrative taxonomy reveals hidden diversity in the Catharus fuscater (Passeriformes: Turdidae) complex in Central and South America. Zoological Journal of the Linnean Society zlad031. LINK

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

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

Soundscapes

Sound is a distinct part of an ecosystem. The soundscapes in the galleries are designed to add another level to the immersive experience – they aren’t just background noise! Many of the species that can be viewed in the exhibits have a corresponding sound in the gallery’s soundscape.

In an ecosystem, sounds are part of an animal’s habitat, offering clues about the surrounding environment as well as being a tool to communicate with others. For example, when a hawk flies by and screams, mice and other rodents nearby will scurry away.

Some of the sounds used in the soundscapes came from the Macaulay Library at Cornell University, which features the largest archive of animal sounds in the world, with new material constantly uploaded. For example, the Pileated Woodpecker sound, heard as part of the Regional Journey’s Temperate Forest soundscape, was initially recorded locally and uploaded to the Macaulay Library by Dr. Matthew Halley, the museum’s Assistant Curator of Birds. These resources help power Cornell’s Merlin app, which can be used by bird watchers in the field to identify birds by photo and sound.

Listen to Dr. Matthew Halley, the museum’s Assistant Curator of Birds, talk about the soundscapes in the Regional Journey Gallery and what we can learn from the sounds we hear.

Transcript: Regional Journey Soundscapes

Hi. Welcome to the Delaware Museum of Nature and Science Regional Journey Gallery. My name is Matthew Halley, and we’re going to talk a little bit about the soundscapes that we hear today in our gallery.

We’ve got multiple habitats that are found in the mid-Atlantic region, a deciduous forest, temperate forest habitat. We have the Delaware Bay and salt marshes and the cypress swamp, and each of these habitats has a different soundscape.

We hear different animals and different crashing waves or the rustling of the leaves. There’s all sorts of sounds that are happening in nature.

When we go into these habitats and the animals are calling out for different reasons that scientists like to argue about, about whether they’re saying, here I am, here I am, or they’re staking a claim to a certain area and resources, or maybe they’re trying to attract a mate or attract some companions.

But regardless of the reason, these animals have to live in a in a soundscape and they listen to all these different sounds and they react to the sounds in their life, which helps them to survive. And when the hawk flies over and gives its scream, you can be sure that the mice that are under the hawk are scurrying into a safe corner.

So, birds make different kinds of sounds and scientists call them calls or songs. But we don’t have any clear-cut definitions for those words. Some sounds are shorter and less complex, such as when a Blue Jay goes “jay…jay.”
Other songs are a lot more complicated. When the robin is singing, it’s warbling song going on and on. It seems like it doesn’t repeat itself very often.

And then we have the mockingbird, which, you know, can go on for an hour, and we don’t hear anything from the same. You know, it’s constantly coming up with new syllables in its song so that we might think of that as kind of a gradient of complexity in bird vocalizations. And one of the things that some that scientists have figured out is that some vocalizations are learned and other vocalizations seem not to be learned.

So, the Phoebe that makes it’s Phoebe, Phoebe call that will develop normally in a baby Phoebe, without hearing an adult. If it grows up in an acoustic isolation chamber, that little Phoebe is still going to say “Phoebe, Phoebe.”

And it’s going to be indistinguishable from a baby Phoebe that grew up in a forest full of Phoebes.
But some other songs: here we’ve got the wood thrush singing in the soundscape, the wood thrush, that flute section in the middle of its song. When you raise a wood thrush in isolation that’s middle, part of the song gets kind of flat and unmusical. And so, it seems that the wood thrush needs to grow up around other wood thrushes to have a tutor to learn how to sing its song correctly.

And when I say correctly, I mean just to sing to produce a normal song that will achieve the functions of the song, whatever they may be, whether it’s territorial defense or attracting a mate. The more your song deviates from the normal, that might have an effect on whether you’re successful surviving or reproducing.

Regional Journey

Four rotating soundscapes in the Regional Journey feature many of the birds seen in the exhibits. Listen closely: there’s also a frog, squirrel, and a fishing reel!

Global Journey

In the Alison K. Bradford Global Journey Gallery, soundscapes including a variety of birds, mammals, and insects rotating through the land-based ecosystems.

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.