Category Archives: Songbirds

Chickadee Nests

Black-capped chickadee (photo from Wikimedia Commons)

Like eastern bluebirds and tree swallows, black-capped and Carolina chickadees are cavity nesters. They place their tiny nests inside woodpecker holes, birdhouses, or in cavities that they excavate on their own.

It takes a week or more for a chickadee pair to make their own nest hole so a suitable birdhouse is a great find for them. Do you have a birdhouse in your yard? Chickadees might have chosen it.

On Throw Back Thursday, here’s what to expect at the Chickadee Nest.

(photo from Wikimedia Commons; click on the caption to see the original)

Another Bird Named Swainson’s

Swainson’s warbler (photo by Bettina Arrigoni via Wikimedia Commons)

I’ve seen the Swainson’s thrush and Swainson’s hawk. My goal last weekend was to hear and see a Swainson’s warbler.

Like the other two birds the Swainson’s warbler (Limnothlypis swainsonii) was named for English ornithologist William J. Swainson (1789-1855) but unlike them he’s hard to find.

To begin with, Swainson’s warblers don’t breed in Pennsylvania. The northernmost corner of their range is a 3.5 hour drive from Pittsburgh. Three of us went to New River Gorge, West Virginia.

Range map of Swainson’s warbler (from Wikimedia Commons)

We found his breeding habitat …

Breeds in southern forests with thick undergrowth, especially canebrakes and floodplain forests in lowlands and rhododendron-mountain laurel in the Appalachians.

from species account at All About Birds

… and stood quietly in a rhododendron thicket where he’s known to breed. We listened for this.

Listening is important. Swainson’s warblers skulk in shadowy, deep thickets and are rarely seen.

We heard one (“He’s in there!”) but he never came out.

Fortunately listening counts.

(photos and maps from Wikimedia Commons, sound from Xeno Canto; click on the captions to see the originals)

p.s. Here’s how thick the rhododendrons are in West Virginia, in a blog post by Samuel Taylor.

Palm Warblers In Yellow Or Brown

Palm warbler, yellow subspecies, on migration in eastern Pennsylvania (photo by Lauri Shaffer)

Palm warblers (Setophaga palmarum) come in two colors — yellow and brown — and both are seen in Pennsylvania during migration, but we rarely see them together. They follow different paths and have different destinations.

Lauri Shaffer (birdingpPictures.com) found a yellow palm warbler at Montour Preserve in eastern PA in early April, above. Bobby Greene photographed a brown one on migration in Ohio a few years ago, below.

Palm warbler, western subspecies, on migration in Ohio (photo by Bobby Greene)

The colors indicate the two subspecies — yellow and western (brown) — that breed in different places, cross over on migration, and overlap their range in winter. The typical range maps don’t tell the story.

Palm warbler range map (from Wikimedia Commons)

Birds of North America Online gives the details, paraphrased below:

Two subspecies of the Palm Warbler exist, easily identified in the field. [They] inhabit separate breeding grounds but overlap on their wintering grounds. The Western Palm Warbler (S. p. palmarum) nests roughly west of Ottawa, Ontario and winters along the southeastern coast of the U.S. and the West Indies. The Yellow Palm Warbler (S. p. hypochrysea) nests east of Ottawa and winters primarily along the Gulf Coast.

paraphrased from Birds of North America Online

For the quickest way to their breeding grounds “yellow” crosses to the Atlantic Flyway in the spring (green arrow going east) while “western” crosses to the Mississippi-Ohio watershed (green arrow going northwest). Their breeding grounds divide at the pink line. On the map it would look like this.

Two subspecies of palm warbler cross over on migration (range map from Wikimedia Commons, annotated by Kate St. John)

If you’re in the Florida Keys in February you’ll see both of them, as Chuck Tague did when he made this slide.

But don’t expect to see them both in Pittsburgh. Ours are the western palm warbler. It’s a rare day when we find a yellow one.

Read more about palm warbler subspecies in Chuck Tague’s blog: Palm Tree Warblers.

(credits: Yellow palm warbler by Lauri Shaffer, BirdingPictures.com. Brown palm warbler by Robert Greene, Jr. Range maps from Wikimedia Commons, annotated by Kate St. John. Brown and yellow comparison by Chuck Tague)

I Can See, But Not Hear Them Singing

Can you hear the golden-crowned kinglets in this video? They are very loud but I can’t hear them at all, though I can see their beaks moving. Their voices are at a high frequency I no longer hear.

All About Birds explains:

Golden-crowned kinglet (photo by Steve Gosser)

Golden-crowned kinglets sing an ascending, accelerating series of up to 14 very high-pitched tsee notes lasting up to 3 seconds and sometimes ending in a musical warble that drops an octave or more in pitch. This is one of the first bird songs that people stop being able to hear as they age. 

All About Birds, Golden-crowned kinglet sounds

If you can’t hear the kinglets you are probably over age 65, perhaps younger, and probably have age-related hearing loss. Presbycusis affects 1 out of 3 of people by age 65 and half of us by age 75. The CDC explains that “the most important sounds we hear every day are in the 250 to 6,000 Hz range.” Kinglets vocalize around 8,000 HZ.

What are HZ? Sounds cause vibrations and are measured in vibrations per second: 1 Hertz (HZ) is 1 vibration/second. High-pitched sounds vibrate faster than low pitched sounds so “high pitch” is also “high frequency.”

At birth humans can hear sounds from about 20 to 20,000 HZ but we start losing our upper range of hearing at age 18! Most of us don’t miss sounds above 17,000HZ but some teenagers in the UK will. They capitalized on the age-related hearing difference by creating a “mosquito whine” ringtone that teachers cannot hear. See and hear it on NPR.

The kinglets in the video are vocalizing at 7700 to 8400 HZ as shown in this graph from the Spectroid app on my mobile phone. The pink scale at the bottom shows the kinglets singing in the 8000 HZ area (at right) and my voice below 5000 HZ (long pink lines on the left). (Top graph shows loudness in decibels.)

So now I have two ways to see golden-crowned kinglets singing. I can watch their beaks or I can watch the Spectroid graph on my mobile phone.

Perhaps if I point my cellphone in the woods I’d see if any golden-crowned kinglets are out there.

p.s. Click here for a video that explains age-related hearing loss & helps you answer the question “How Old Are Your Ears?

(photo of golden-crowned kinglet by Steve Gosser, Spectroid graph recorded by Kate St. John; video by The Wood Thrush Shop on YouTube)

Tree Swallows Soon

Tree swallows fighting over a nest box (photo from Wikimedia Commons)

You might not see any tree swallows in Pittsburgh yet, but there are flocks in the north at Custards, Geneva Marsh and the Linesville Fish Hatchery.

Last Tuesday March 19 Patience Fisher and I were amazed by the millions of midges in the air at Custards. There were so many that they coated my car and attracted hundreds of tree swallows that wheeled over the marsh.

Tree swallows (Tachycineta bicolor) are short distance migrants who spend the winter as close to us as coastal North Carolina. The males tend to migrate first and arrive on the breeding grounds to claim territory and fight over nest sites, including bluebird boxes. When the females arrive they pair up quickly and place a little nesting material in their chosen nest site. The pair won’t nest for a few weeks but they like to stake their claim early.

Keep an eye out for tree swallows in the days and weeks ahead … and hope for warm weather so they have enough insects to eat.

Tree swallows are coming soon.

(photo from Wikimedia Commons; click on the caption to see the original)

Versatile White-Eyes

Japanese white-eye in Kauai, Hawaii (photo by Dick Daniels via Wikimedia Commons)

Seven years ago I wrote about the beautiful white eye ring on a bird named the silvereye (Zosterops lateralis), native to Australia and New Zealand. In Hawaii I saw a similar bird, the Japanese white-eye (Zosterops japonicus).

They’re different species in the same genus, Zosterops.

Japanese white-eye and silvereye (photos from Wikimedia Commons)

It turns out there are 100 species in the Zosterops genus (minus three recently extinct). They range from Africa to India, Southeast Asia, China, Japan, Australia and many islands in the Indian and Pacific oceans.

These versatile little birds — only the size of a chickadee — usually arrive at new locations on their own. They showed up in New Zealand in 1832 and 1856, presumably blown east in a storm from Australia.

Humans helped white-eyes get to Hawaii. We introduced Japanese white-eyes to Oahu in 1929, but these resourceful little birds have now spread to all the other Hawaiian Islands.

Wherever they go, Zosterops tend to differentiate themselves quickly and become new species. Maybe the Japanese white-eye in Hawaii will morph into the “Hawaiian white-eye” in a few hundred years.

See more about the silvereye in this vintage blog: Eye Ring.

Tell Me Who’s Singing

Ovenbird singing (photo by budgora on Flickr, Creative Commons license)

Have you ever wished for a tool that could accurately identify a single bird’s voice among dozens of singers? You aren’t alone. Ornithologists are eager for a way to census birds using field recordings, but the sheer volume of data and complexity of bird song makes this a daunting task. A free tool that can identify huge volumes of song data doesn’t exist yet, but the Kitzes Lab at the University of Pittsburgh is creating one.

In December 2018 Assistant Professor Justin Kitzes of the Department of Biological Sciences won an AI for Earth Innovation Grant, awarded by Microsoft and National Geographic, to develop the first free open source model for identifying bird songs in acoustic field recordings. Its name is OpenSoundscape.

OpenSoundscape uses machine learning, a subset of artificial intelligence (AI), to scan recorded birdsong and algorithmic hunches to arrive at a song’s identity. To do this the Kitzes Lab starts with real life recordings.

The team places small AudioMoth recorders in an array in the forest, much the same way human observers do point counts except that the Audio Moths are all recording at the same time.

Audio Moth in the field(photo courtesy Kitzes Lab)

The team brings the recorders back to the lab and downloads the sound files to the database. (Some day the software will be able to triangulate GPS from several Audio Moths and determine a single songbird’s location!)

AudioMoth recorder used by field study at Kitzes Lab (photo by Kate St. John)

Here’s one recording of at least six individual birds. OpenSoundscape is learning how to identify them.

An Audio Moth recording from the field (courtesy Kitzes Lab)

It makes a spectrogram of the sound file (below), then picks out each pattern and uses algorithms and the classifier library to identify the individual songs.

The more songs it successfully identifies, the better its algorithms become.

By the end of 2019 the OpenSoundscape models, software, and classifier library of birdsong will be ready for researchers on a laptop, cloud service or supercomputer. Ornithologists will be able to gather tons of data in the field and find out who was singing.

p.s. WESA featured this project in their Tech Report on 26 Feb 2019. Click here to listen.

(credits: photo of ovenbird by budgora on Flickr, Creative Commons license. Photo of Audio Moth on a desk by Kate St. John. All other photos and sound file, courtesy the Kitzes Lab)