On Exhibit: Voices in Flight
Bird songs tell rich stories of territory, courtship, and identity.
Explore these stories in three different ways: photographs of birds captured mid-song, scientific sonograms at the museum that visualize each unique vocalization, and audio recordings here.
Each photograph by Lew Scharpf freezes a fleeting moment as a bird lifts its beak and fills the air with sound. The sonograms, on exhibit at the museum and created by Matthew Halley using software by Cornell Lab of Ornithology, translate those songs into a visual language — patterns of frequency and time that make the invisible audible. Many recordings were made by Dr. Halley, with additional audio from xeno-canto.org.
Song Sparrow
(Thyothorus carolinensis)
The pleasing song of this species is a series of trills and clear whistles. It can be heard in pretty much any open or brushy habitat, including residential neighborhoods and farmers’ fields. They live year-round in Delaware and often form small flocks during the breeding season.
Recorded by Matthew R. Halley on 28 April 2020 in Philadelphia Co., PA.
Great Horned Owl
(Thyothorus carolinensis)
The rhythmic, muffled hoots of this species are uttered at very low frequency (less than 1 kHz) — look for the dark lines at the very bottom of the sonogram.
Recorded by David Darrell-Lambert on 17 May 2019 in Essex Co., ON, Canada.
Northern Flicker
(Colaptes auratus)
The loud “fleer” call of this species often alerts birders to its presence in nearby woodlands. Unlike most woodpeckers, flickers are frequently seen foraging on the ground in open areas, eating ants and other insects.
Recorded by Stanislas Wroza on 21 May 2025 in Portneuf, QC, Canada.
Bald Eagle
(Haliaeetus leucocephalus)
The voice of the Bald Eagle is a series of weak chirping whistles — maybe not what you would expect from a
fearsome predator. Because of this, in movies and television programs, the scream of the Red-tailed Hawk (Buteo jamaicensis) is often dubbed in, to make the eagle seem fiercer than it is!
Recorded by Bruce Lagerquist on 16 November 2022 in Clallam Co., WA.
White-breasted Nuthatch
(Sitta carolinensis)
The short nasal calls of this species (“yenk, yenk”) can be heard in open woods with mature trees, especially oaks and pines. They cling to the trunks of trees and can even be seen clambering down head-first, peeking under layers of bark for food.
Recorded by Jim Berry on 21 May 2016 in Chautaqua Co., NY.
Downy Woodpecker
(Dryobates pubescens)
Get to know the squeaky “rattle call” of this species and you will soon be hearing it all over the neighborhood. These small woodpeckers are common residents of our local woodlands and gardens, but more often heard than seen.
Recorded by Jim Berry on 24 August 2016 in Chautauqua Co., NY.
Eastern Phoebe
(Poecile carolinensis)
Listen for the “phoebe!” song and its subtle variants (pictured) in early March. This is one of the first migratory songbirds to return to our region in the spring. Scientists have shown with experiments that the song is encoded in the bird’s DNA — no learning required!
Recorded by Matthew R. Halley on 28 April 2020 in Philadelphia Co., PA.
American Robin
(Turdus migratorius)
The song of this common species is a series of short, warbled phrases. Robins can only hear up to about 8.7 kHZ — the dark horizontal line in the sonogram — which means that we could make a high-pitched whistle that humans could hear, but robins could not!
Recorded by Matthew R. Halley on 29 April 2020 in Philadelphia Co., PA.
Red-tailed Hawk
(Poecile carolinensis)
The raspy scream of this species will send shivers down your spine! These hawks are often seen soaring over fields, tracing lazy circles in the sky as they search for food—small mammals are their preference. They often perch on telephone poles and other man-made structures. But take note—immature red-tailed hawks do not have red tails!
Recorded by Allen T. Chartier on 24 June 2008 in St. Clair Co., MI.
Carolina Wren
(Thyothorus carolinensis)
The song of this species is a rolling series of emphatic whistled phrases, usually 3 or 4 syllables long each. For example, you might hear it singing something that sounds like “tea kettle, tea kettle!” or “generator! generator!” It is commonly heard in woodlots throughout the Mid-Atlantic region.
Recorded by Matthew R. Halley on 22 April 2020 in Philadelphia Co., PA.
Red-bellied Woodpecker
(Melanerpes carolinus)
This common species makes a loud “chhrrrrr” call with a slightly rising inflection. They thrive in open woodlands and often come to backyard suet feeders.
Recorded by Christopher McPherson on 20 May 2019 in Hillsborough Co., NH.
Northern Mockingbird
(Thyothorus carolinensis)
This species is so famous for mimicking the songs of other species that is was given the scientific name “polyglottos,” meaning “speaks many languages.” Sometimes, you will hear mockingbirds singing very late at night. This recording was made after midnight!
Recorded by Matthew R. Halley on 5 June 2022 in Chester Co., PA.
Carolina Chickadee
(Poecile carolinensis)
The song of this familiar species at backyard feeders is a series of four sweet whistles, often referred to by the phrase “fee bee fee bay” or, in this case, “fee bay bay bay.”
Recorded by Thomas Magarian on 13 May 2024 in Page Co., VA.
Pine Siskin
(Poecile carolinensis)
This northern species visits Delaware in the winter and prefers open coniferous forest. Its song is a rapid jumble of husky notes. Look for the “streaky” goldfinch at your bird feeder!
Recorded by Stanislas Wroza on 4 June 2025 in Capitale-Nationale, QC, Canada.
Cedar Waxwing
(Bombycilla cedrorum)
The song of this species is a simple series of high-pitched whistles with an irregular rhythm— “sreeee! sreeee!” The fundamental frequency is usually between 6–8 kHZ. This recording provides a great visual example of Ohm’s Law of acoustics: the first overtone is twice the frequency of the fundamental.
Recorded by Valerie Heemstra on 17 August 2023 in Delta Co., MI.
About the contributors
Lew Scharpf, Ph.D.
Lew Scharpf brings expertise in biochemical research, spanning both industry and academia, to his volunteer work here. He is a musician, photographer and avid birder.
Matthew R. Halley, Ph.D.
Matthew Halley is a scientist, historian, and musician whose work spans evolutionary biology, animal behavior, and the history of science. As the museum’s Research Director and Curator of Birds, he oversees the bird collection and conducts specimen-based research using methods ranging from DNA analysis to audio recording.