Sunday, June 23, 2019

Snarls and Snores

Leopard Frog? Pickerel Frog? This identification question seems to come up quite a bit for people who are listening to frog songs. Citizen scientists who participate in FrogWatch do their surveys at night, so these folks always have to gather data by ear. 

A number of frog species are quite distinct from one another, particularly with a side-by-side recording reminder. There are a few, however, that people tend to have trouble identifying. 

For example, people generally know the Spring Peeper’s common and relentlessly loud peeping calls. What they often find confusing is the Spring Peeper’s ascending trill calls and the calls of the Western Chorus Frog, especially because these two species may be found calling in the same location.

Western Chorus Frog, above and Spring Peeper, below. 

Listen to this comparison of the Western Chorus Frog followed by the Spring Peeper’s trill call. The trilling peeper is much more melodious to human ears because the pitches are not as high as those of the Western Chorus Frog and therefore sound clearer to us. In fact, they fall into the same range as many bird songs. 

Another point of confusion can be the Gray Treefrogs. Up here in NE Ohio, we have Gray Treefrogs but not the visually identical Cope’s Gray Treefrog. Southern Ohio residents have Cope’s Gray Treefrog AND there are locations where both species are present. 

If that’s true for you – or if you’re visiting Cope’s country – you can learn the difference if you’ll graciously grant yourself a little patience. I’ll include an example below and also this link to the Listening in Nature post that features both calls if you’d like to do some additional listening.

And then there’s Leopard and Pickerel Frogs. Some people say, “I don’t even try.” So let’s spend a little time with this comparison and experiment with some approaches you might find helpful in separating these two species. 

First, a quick reminder of some visual similarities and differences. These frogs are about the same size. Leopard Frogs are generally green and the Pickerel Frogs tan, and both have prominent dark spots. The Leopard Frog’s spots appear more random than the paired rows of Pickerel Frog spots. I find this distinction to be very helpful.

Here are Leopard Frog spots...

 ...and here are Pickerel Frog spots.


Both species call in April after the Wood Frogs have finished and the Spring Peepers and Western Chorus Frogs have already been calling for perhaps a month. It seems to me that the Pickerels start a little later than Leopards, though I don't know if that's consistently true. I also have not heard both species in the same places, though again, that may not be true elsewhere.

Although The Ohio Frog and Toad Calling Survey states that Pickerel Frogs “utilize the margins of clear, cool streams, woodland springs and seeps, fens, and wet meadows,” this isn’t necessarily true in my corner of NE Ohio. I’ve only found them in lakes, ponds, and marshes so far, so keep that possibility in mind. 

Now about listening. Let’s start with the Leopard Frog. 

They can call underwater, as can Pickerels, so you may not always know exactly where the sound is coming from. Although their calls are often described as sounding like snoring, listen for variation. I’ll give you some examples.

They can make grunting sounds, and sometimes their “snore” can be a rather dramatic roar instead.  

You may hear a relatively smooth, continuous sound or one that has lots of tiny separations in the sound’s flow. I describe it as "eh-eh-eh-eh-eh" and you can see the separations on the sonogram. 

I’ve focused on individual calls and small groups for detail. Now here's a large, glorious chorus at Killbuck Marsh Wildlife Area near Shreve (a little south of Wooster). When I recorded this inspiring chorus (photo below), I was literally standing in the water with them. Could I see them? Not really, but they were never far from my boots as I slowly sloshed through the water.

OK, got it? Now on to the Pickerel Frogs.

Brad Phillips at Erie (County) MetroParks described their song to me as a “snarl,” and I think that’s useful to remember. It’s definitely a smoother sound than those of the Leopard Frogs. (Personally, I think Pickerel Frogs can also sound at times like a growling stomach.)

The songs start softer and quickly become louder. (Imagine snarling "Nyeeaaahh!" at someone.) You can see the contour on the sonogram I’ve included.  The steady band of sound that runs through this sonogram (and recording) is that relentlessly loud chorus of Spring Peepers I mentioned earlier.

Now here's a chorus of several Pickerel Frogs and, of course, Spring Peepers.

A useful way to remember similar calls like these is to try imitating each one. 

If I were to imitate the Pickerel Frog, I would say “errrahh” beginning with my jaw clenched and lips apart, then gradually open my jaw a little and slowly closing it again. "Nyeeaaah" works pretty well, too.

But for the Leopard Frog, I would open my jaw farther before closing it, and I’d also do a “rrrah-ah-ah-ah-ah-ah” at times for the call type that has more spaces.

For both species, try to make the sound as guttural as you can. Don’t sing it; you are growling and snarling. 

Now go back and listen to the frog calls and imitate them as best you can. Improvise as needed - you may find it amusing as well as useful to find the sounds that work best for you. 

Then try immediately to recall what you did and how you did it. You don’t have to do all this in front of anyone, though if you do, you can both break down into uncontrollable laughter afterward. But you will remember the songs better!

Here's a practice track for you: Pickerel Frogs first (accompanied by Spring Peepers) followed by different Leopard Frog calls. 

What was similar? Different? What did you do to create those songs, and can you recreate them now? Actually making similar sounds yourself can be very helpful in remembering because you didn’t just listen - you did something with your own body to create a similar sound. It involves muscle memory. 

OK, Frog Watchers – or should I say, Frog Listeners! Refer back to this post next April if it's beneficial. In the meantime, we still have Green Frogs, Bullfrogs, and the lovely Gray Treefrogs calling, so keep listening...

The Ohio Frog and Toad Calling Survey

I’ll include a Google map of where I’ve recorded them so far and also reports from naturalists in the region. I’ll update the map as I get more information. I’m interested in where we have Pickerel Frogs in our region, and you’ll probably want to know where this is an option when you’re doing surveys.

Thursday, May 30, 2019

Dawn Chorus on a Sheep Farm

Have you heard of the Dawn Chorus events that are common in Britain? I certainly hadn’t until recently. They take place in May in bird-friendly habitats such as parks. People gather outdoors in the darkness, listening from the very first birdsong of approaching dawn until the full chorus has begun to sing after sunrise. Sometimes the participants then have breakfast together. It sounds delightful, doesn’t it?

From what I’ve been able to find online, the tradition began in England in the 1980s, spread across the rest of the U.K, then expanded to other parts of Europe as well. There is now an annual International Dawn Chorus Day on first Sunday of May, and it’s been celebrated in over 80 countries! 

Betsy Stebbins-Anderson searched the internet for indications of International Dawn Chorus Day in the U.S. but didn’t find any. It was time. A family member who was an avid birder had done her own personal Dawn Chorus morning each May for 20 years until the end of her life, and Betsy decided to continue the Dawn Chorus morning here in Ohio.

The location would be on the family’s 186-acre Summerhill sheep farm near Shreve (a little south of Wooster). Betsy had contacted me about being the birdsong guide, and I thought it was an intriguing idea. And yes, there would be an outdoor breakfast for everyone after sunrise. Following  breakfast, I would then lead a morning birdsong listening hike through various habitats on the farm. 

Although there was some distant sound from agricultural equipment on a neighboring farm when we arrived, it was still much quieter than most places I try to record. Walking up the hill from the sheep, I noticed that the songs hurled back and forth between the Chipping Sparrows seemed to sparkle! Was I able to hear more of their highest frequencies than usual?  And the Red-winged Blackbird’s screams - always quite bellicose - were even more potent that I would have expected. 

Look at the sonogram: you’ll see the high, steady trills of the Chipping Sparrows and the lower hooked-shaped screams of the Red-winged Blackbird. The latter species has a number of different calls, and I suspect that each one is either a threat or vulgar insult.

The view up on the hill at sunset created a sense of space inside me as well as around me, and I would have liked to have stayed outside well after dark. However, Wendy and I would be getting up at 4 AM - unimaginable for a night person like myself – and ready to communicate with other humans by about 4:30. 

People began to gather even before 5:00, and the earliest arrivals were the ones who heard the first birdsong of pre-dawn. You’re probably thinking it was a Robin, or maybe a Cardinal, but no - it was a Song Sparrow at 4:45. He was followed a 5:02 by a Chipping Sparrow, and only at 5:06 did the first Robin take the stage.

Soon, more Robins began to sing, followed by Barn Swallows, a Field Sparrow, Killdeer, Northern Cardinals and a Chickadee. (Although Summerhill Farm is in the overlap zone between Black-capped and Carolina Chickadees, this one was singing the Black-capped song.) 

We quietly walked on the narrow road along the edge of the farm, and were soon challenged by the number of bird species beginning their dawn songs. Wendy kept the list as we softly announced the name of each new singer.

Just the Catbird, Tufted Titmouse, and House Wren together sounded like a chorus! I'll focus on each one in this track so you can get a better idea of who is singing. The sonogram is primarily the Catbird.

Behind the wall of Robin song, I heard a Field Sparrow singing an atypically complex, three-part song that I’ve occasionally heard elsewhere. Later in the morning, this Field Sparrow and any others we heard were singing the expected accelerating trill. Here’s an example of the early morning song.

We'd all heard birds at dawn before, but our attentiveness and focused listening enhanced our sense of wonder. The birds revealed themselves with their songs; we didn’t actually see most of them. Songs and calls are how they communicate with each other, and we humans were just privileged listeners. 

By 6:52, we had heard 32 bird species - including a calling Sandhill Crane.

After a splendid breakfast, we returned to listening to the birds while walking under the morning sun. Other family members have houses on the farm, and Carolina Wrens were happy to make their homes near them. If they are present you will certainly hear them. 

Unlike House Wrens, Carolina Wrens do not migrate and need to manage Ohio winters. While less common in the snow belt counties of NE Ohio (though increasing in numbers as winters become milder) they seem to be plentiful south of Cleveland.

I didn’t expect our walk to take us down through a large field and into a woodland.  The bird songs we heard quickly changed to a new habitat-specific ensemble. A woodland doesn’t sound like a meadow, and Summerhill Farm’s Savannah Sparrows and Eastern Meadowlarks would not be singing in the woods. 

Instead, we now heard the Red-eyed Vireo, Wood Thrush, Rose-breasted Grosbeak, Acadian Flycatcher, a Barred Owl calling…and what was that in the background near the small, wet opening in trees near the Yellow-throated Vireo’s song? Could it be a Cerulean Warbler? 

I was able to get closer, and it most certainly was a Cerulean - always a very nice discovery! I haven’t had many opportunities to hear them on territory.  But John and Betsy are very conscientious about caring for the habitats on the farm, so it is no coincidence that this rich chorus of woodland singers could be found on their property. Protecting habitats - the concert halls, as I sometimes describe them - protects the birdsong ensembles.  

Heat and humidity were increasing with the sun’s intensity as we headed uphill back toward the house past the Savannah and Song Sparrows. The Dawn Chorus morning was ending, but could it really be only 10:15? 

Before we left the farm, I had to pay one last visit to the sheep. I was still intrigued by the vocal variation and nuance in their calls and could hear each one as an individual more easily than I could ever visually recognize them. While you listen to my favorite recording of the lambs and sheep, you can read the list of birds we heard.

You can find Summerhill Farm on Facebook, where you can watch their page for other events like this one. Betsy plans to do the Dawn Chorus event annually. As for me, this lifelong night person would be delighted to get up once a year at 4 AM before returning to her nocturnal ways.

Except for the opening and closing sheep photos, the photos of the Dawn Chorus morning were provided by Summerhill Farm.