Can we call it love song?

The early risers among us may have noticed that songbirds are singing again. For Northern Cardinals and Carolina Wrens in our gardens spring has started with the change in day length on December 21. One can really notice now that the mornings get light earlier with every day and the males of our local songbird species are getting ready for the next breeding season. They set up territory and woo females. But more about our local birds on Friday, let’s travel to the tropics!

In the tropics, birds barely take a break from singing. If conditions allow it, they will breed year-round and thus most of them keep their territory and mate. Such long-term relations call for special communications: males and females of many neo-tropical wrens sing very precisely coordinated duets. For the untrained listener it may sound like one song, that’s how closely the phrases are linked. Researchers, however, have shown that both male and female contribute to this continuous song, thus performing a duet.

Can you hear whether these are two birds singing or one?

Sandy Gaunt, curator emerita from the Borror lab and longtime volunteer, recorded these Stripe-breasted Wrens Cantorchilus thoracicus in the dense undergrowth of the tropical lowland wet forest in Costa Rica on no other day than February 14 in 1992. Sandy found these birds near the Hitoy Cerere Biological Reserve, southwest of Puerto Limon in Costa Rica, a rugged and undeveloped park with abundant wildlife.

The song of a close relative to the Stripe-breasted Wren, the Plain Wren Cantorchilus modestus zeledoni, has been studied in some detail by Karla Rivera-Cáceres from the University of Miami, Florida. These wrens perform precisely coordinated duets as you can see for yourself in the spectrogram below – a visual representation of sound with frequency or perceived pitch over time. Both males and females adjust their song and pauses between songs to coordinate with their partner. Red bars indicate the female’s contribution, bluish bars the male’s.

Spectrogram of highly coordinated Plain Wren duet

Highly coordinated duet of male and female Plain Wrens (Fig.1 in Rivera-Caceres et al 2016)

Listen to these male and female Plain Wrens duetting as recorded by Jacob R. Saucier. The recording is archived with Xeno-canto, an online collection of bird songs from around the world (XC319021).

spectrogram of Plain Wren duet (XC319021)

Duet of male and female Plain Wren as recorded by Jacob R. Saucier (XC319021).

So, shall we call this a love song? There are many hypotheses for why birds duet, one suggests that the level of coordination may signal pair bond strength, the level of commitment a mated male and female have of cooperating with one another. Other hypotheses suggest that duetting may help mates to stay in contact in dense habitat, or two singing birds may be more intimidating and thus more effective when defending a territory. Future research will show which of these hypothesis is most likely for the Stripe-breasted Wren.

 

Reference:

Rivera-Cáceres, K. D., Quirós-Guerrero, E., Araya-Salas, M., & Searcy, W. A. (2016, November). Neotropical wrens learn new duet rules as adults. In Proc. R. Soc. B (Vol. 283, No. 1843). The Royal Society.

 

About the Author: Angelika Nelson is the curator of the Borror Laboratory of Bioacoustics and instructor for the OSU Ohio Birds class each spring.

 

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The holy grail of sound recognition: a birdsong recognition app

Listen to the cacophony of bird sounds at dawn. Does it make you want to be able to tell which species chime in? Wouldn’t it be nice to have an app “listen” with you and list all the bird species that are vocalizing? You are not alone, this is what researchers have been and are still working on. If you are somewhat familiar with bird song, you can imagine that it is not an easy task. Every species has its own characteristic sounds. But even within a species every individual most likely sings more than one rendition of the species-specific song and does so with variations.

Listen to the songs of the Yellow Warbler, Chestnut-sided Warbler and Yellow-throated Warbler, three species in the wood warbler family, that commonly sing in Ohio in spring.

Here is an example of two different song types sung by the same Yellow Warbler male:

Training software

To develop a bird song recognition app, software needs to be trained with real bird songs. An animal sound archive that houses thousands of recordings is an ideal resource for this endeavor. The Borror lab has provided many of our 47,000+ recordings to different researchers. Recently, Dr. Peter Jančovic, Senior Lecturer in the Department of Electronic, Electrical and Systems Engineering at the University of Birmingham, UK collaborated with us. He and his colleagues developed and tested an algorithm on over 33 hours of field recordings, containing 30 bird species (To put this in perspective, to-date 10,000 species of birds have been described and half of them are songbirds – so 30 species is really only the tip of the iceberg). But, his results are promising, the developed system recognizes bird species with an accuracy of 97.8% using 3 seconds of the detected signal. He presented these first results at the  International Conference on Acoustics, Speech and Signal Processing in Shanghai.

Sonogram of Yellow Warbler, not Yellow-throated Warbler song

The software correctly identified this sonogram as song from a Yellow Warbler.

Birdsong recognition apps

Some prototypes of birdsong recognition software and apps are already on the market.

bird song recognition apps: Warblr, Chirpomatic, Birdgenie

These are some of the already available bird song recognition apps that you may want to try.

 

Think of them as the Shazam of birdsong (For those of you not familiar with Shazam, it is an app that identifies music for you). Instead of sampling audio being played you record the bird’s song in question. The software will then compare features of the recorded sound against a database based on pre-recorded, identified sounds, a sound library.

 

Challenges and problems

This simple sounding process has challenges and problems: You need to get a really good recording of the bird you want to identify, i.e. no other birds singing nearby, no traffic noise, people talking or lawn mowers obscuring your target sound. Once you have managed this, a good app takes into account where in the world, even within the USA and within Ohio you recorded the song. Birds sing with local variations. Research in our lab has focused on this for many years: Birds learn their songs by imitating conspecific adults where they grow up and will incorporate any variations these birds sing in their repertoire. Thus the recorded sounds need to be compared to geographically correct songs of each species. Once the location has been set, the app needs to compare the recording to thousands of songs, because most of our songbirds sing at least 5 types of typical song, some sing over 100. Some like the Northern Mockingbird imitate the sounds of other species.

Geographic variation in song of Yellow Warbler YEWA

Listen to and compare Yellow Warbler songs from Ohio, Maine and Mexico, Baja California and Sonora.

I hope I have not completely discouraged you from trying one of the bird song recognition apps. They truly are an innovative application of the thousands of songs that have been recorded, archived and can be listened to for free. Have you already tried one of these apps? We would love to hear your experiences!

 

About the Author: Angelika Nelson is the curator of the Borror Laboratory of Bioacoustics.

 

Resources:

Jančovic, M. Köküer, M. Zakeri and M. Russell, “Bird species recognition using HMM-based unsupervised modelling of individual syllables with incorporated duration modelling,” 2016 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), Shanghai, 2016, pp. 559-563. doi: 10.1109/ICASSP.2016.7471737

Bird song ID apps

USA:
Bird Song Id USA Automatic Recognition and Reference – Songs and Calls of America
BirdGenie

UK:
Chirpomatic
Warblr

A comparison of Chirpomatic and Warblr for birds recorded in the UK.

Song Sparrow recordings

Inspired by Monday’s post about Margaret Morse Nice I looked up recordings of Song Sparrows in our collection. I found more than 1,600 recordings from 27 states in the USA and Canada. I was hoping to find recordings from Margaret Morse Nice’s former study area in her backyard, now Tuttle park, just north of the Lane Avenue bridge along the east side of the Olentangy river.

map of Recording locations on OSU main campus

Recording locations on OSU main campus

Instead I located a cluster of recordings in Franklin County: Don Borror, founder of our lab, recorded Song Sparrows on the OSU main campus in 1948 and 1953. [Note that these are among the earliest preserved sound recordings – the earliest existing recording in the USA is of a Song Sparrow recorded by Cornell Lab founder and pioneer in sound recording Arthur Allen in 1929.]

When we describe variation within and differences among songs, in addition to listening to recordings we often visualize sounds. We use sound analysis software to produce spectrograms that show the frequency of sound vibrations, which we perceive as pitch, over time. The darkness of the spectrogram indicates the loudness of the sound. See for yourself in this short video of one song of a Song Sparrow played in the software RAVEN, follow the moving bar while you listen – can you hear the difference among the notes?

 

Now listen to the variety of songs that Don Borror recorded on OSU campus and try to match them with the corresponding sonograms.   Tip: Hover your mouse over each of the spectrograms to reveal the number corresponding to the sound files below. This will help you to verify your match.

If you have enjoyed this sound matching game, I can recommend playing “Bird Song Hero“, a matching game set up by the Cornell Lab of Ornithology. You will not only perfect your skills in matching spectrograms to heard sound but will also learn the songs of some common garden birds. Enjoy!

 

About the Author: Angelika Nelson is the curator of the Borror Laboratory of Bioacoustics. Her recent research has focused on song and behavioral ecology of the White-crowned Sparrow in Oregon; each spring Angelika teaches the OSU course “Ohio Birds” where students learn about the life of birds and how to identify them in the field – by sight and sound.

 

Different songs for different places

In my last post I talked about how Carolina Chickadee songs have changed (or not) in Columbus and the surrounding areas over the past ~60 years. This post takes a different perspective on how Carolina Chickadee songs can vary: over geographic space. If you were paying close attention in the last post, you may have gotten a sense of geographic variation in song even on a scale as small as Columbus – some songs only appeared in certain areas during certain time periods.

One major component of my dissertation here at OSU has been to quantify how Carolina chickadee songs vary over their entire range, the southeastern United States, and compare this variation to geographic variation in their sister species, the Black-capped Chickadee. Despite Carolina Chickadees being very common birds, not many recordings of their songs were archived in museum collections for me to use. The Borror Lab had the most recordings, but the vast majority of those were made in Ohio.

So in spring of 2014 I embarked on an expedition to record as many Carolina Chickadees in as many different places as possible. Over 5 and a half weeks (divided into three trips), I drove about 6,000 miles through 22 states and recorded over 120 chickadees.

Sample locations during recording trip in 2014

Sample locations during recording trip in 2014

Below are samples of some of the atypical songs that I recorded on my trip. The full Carolina chickadee range is shaded in orange. All the spectrograms shown are on the same scale, so you can directly compare them to one another (the upper limit of each spectrogram image is about 10 kHz). Not included are songs or spectrograms of the typical alternating high-low-high-low Carolina chickadee song, which was also present at most sample locations.

  1. Newark, Delaware

CACH-DE

 

 

 

 

2. Kensington, Maryland

CACH-MD

 

 

 

 

3. Asheboro, North Carolina

CACH-NC

 

 

 

 

 

4. Cartersville, Georgia

CACH-GA

 

 

 

 

5. Camden, Alabama

CACH-AL

 

 

 

 

6. Ajax, Louisiana

CACH-LA

 

 

 

 

7. Meridian, Texas

CACH-TX

 

 

 

 

8. Moyers, Oklahoma

CACH-OK

 

 

 

 

9. Crossville, Tennessee

CACH-TN

 

 

 

10. Salem, Missouri

CACH-MO

 

 

 

 

11. Makanda, Illinois

CACH-IL

 

 

 

 

12. Mammoth Cave, Kentucky

CACH-KY

 

 

 

 

 

About the author:  Stephanie Wright Nelson is a graduate student in the department of EEOBiology. She studies song learning in chickadees and is particularly interested in the consequences of hybridization between Carolina and Black-capped Chickadees.