A Dark-eyed Junco singing in a boreal forest. Photo: Thomas Gianoli
By Thomas Gianoli, Bird Monitoring Biologist – Northern Canada
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Let’s imagine ourselves back in February, a month characterized by severe cold and abundant snow. Through my office window, I observe the winter landscape, where the world seems still. Only a handful of hardy birds are present, struggling against the elements. As I settle into my chair, sipping my coffee, I plug in my headphones, select an audio file recorded by one of our autonomous recording units (ARUs), and hit “play”. Immediately, natural sounds envelop me, as if I’ve traveled back in time. The leaves and branches of the trees sway in the breeze, while a distant stream flows. The soundtrack is a symphony of different melodies, performed by a variety of musicians: the thrushes, warblers and sparrows on vocals with the woodpeckers and grouse on percussion. Each bird has its own distinct signature, which is visible and identifiable thanks to the spectrograms of the sound recordings.
I feel blessed to hear the vibrant and dynamic sound of the boreal forest at its peak of life and energy. This landscape is inaccessible to most people. The zen aspect of these recording projects is quite remarkable. However, you need to maintain intense concentration to detect the songs of more distant birds, singing many meters away from where the ARU was installed.
The variety and multitude of birds in the boreal forest during the breeding season can be overwhelming, and picking out a warbler’s song among the chorus of White-throated Sparrows can be a daunting, yet rewarding, challenge. And with ARU projects helping to improve our knowledge of species distribution, identifying a threatened or rare species in a particular location always brings a sense of joy and, I must admit, a little pride.
About spectrograms… here is an example:
An autonomous recording unit (ARU) deployed on a balsam fir. Photo: Sasha Chillibeck
The dark lines represent bird vocalizations. The darker they are, the closer the birds are to the recorder. On the left is the frequency scale in hertz. In this example we can see the lines corresponding to the voices of a Yellow-bellied Flycatcher (A), a Black-and-white Warbler (B), a Common Yellowthroat (C), a White-throated Sparrow (D) and a Lincoln’s Sparrow (E). Can you recognize them? With practice, just by looking at these signatures, we can identify the birds and even imagine their songs in our heads. This is a great tool, even for identifying common species during our birding outings. What’s more, it keeps me ready for the birds’ return in the spring. It’s like a winter rust remover for bird calls. Not to be underestimated!
Why do we listen to bird sound recordings?
In Canada, as well as globally, bird surveys conducted during the breeding season are crucial for gathering valuable data on population dynamics. Various summer survey methods are employed, including Breeding Bird Atlases, the Breeding Bird Survey (BBS), the Marsh Monitoring Program, and the more specialized High Elevation Landbird Program which targets Bicknell’s Thrush habitat. These are just a few examples. Every year, we can track the fluctuations in bird populations throughout Canada, allowing us to take action for their long-term conservation. Yet the country is vast, with remote regions that are difficult or even impossible to access by car. And, unfortunately, we can’t be in multiple places simultaneously, making it a challenge to cover all areas, especially the boreal forest and the Canadian Arctic. Despite enormous efforts over the past few decades to map their northern distribution, many bird species remain a mystery.
This is where technology and Indigenous knowledge come into play, allowing us to lift the veil on these unknowns. One such emerging technology is ARUs, small devices that can be deployed for long periods and programmed to capture the sounds of the surrounding environment. More and more Indigenous community-led projects are using this technology, which is becoming increasingly accessible and easier to deploy. Birds Canada programs, such as Science in the North, support these projects in northern Ontario, northern Quebec, and Labrador, often collaborating with partners like Environment and Climate Change Canada or First Nations of Quebec and Labrador Sustainable Development Institute, to create synergies in our common efforts. Keeping in mind the priorities and needs of our valuable bird conservation partners and collaborators, we help them carry out the desired inventories. We also ensure that Indigenous communities enjoy long-term autonomy over all types of bird monitoring efforts. These units, deployed for the whole summer, can provide hundreds and hundreds of hours of audio recordings, which are stored on memory cards.
ARUs, deployed for the whole summer, can provide hundreds and hundreds of hours of audio recordings, which are stored on memory cards.
After the field season, these sound files are analyzed by experienced biologists and ornithologists. They allow us to discover the diversity of birds present in a given place. I was told once that ARU data provides a long-term signature of the natural landscape, which could not be more true. Just imagine that we can know exactly which species sang at what exact moment in a specific location. We can listen to its song as many times as we want, and compare it with the recordings made in future years. We can immediately detect changes in the occurrence and even in the vocalizations of a given species. Isn’t that amazing? I find it extraordinary that we can do this today, and it makes my work all the more exciting!
The new field season is beginning, and migratory birds are returning to their breeding grounds. The awakening of nature is in progress. Birds Canada’s staff and volunteers are hard at work organizing the deployment and retrieval of new ARUs with partners and collaborators across Canada, in known and remote locations, to reveal the secrets of avian life. New data, new discoveries, new surprises, and new concerts by the same feathered artists whom we have listened to in our offices over the last few months. A summer season filled with northern melodies, which will fill our next winter.