Sounds, Like a Good Idea

Although many of us have appreciated the melody of birdsong, the buzzing of insects, and the noises of wildlife, we might not realize just how unique and important these sounds are.

Across the globe, scientists, naturalists, and wildlife aficionados tune into wildlife sounds to inventory species, track ecosystem health, and delve into animal language. Bioacoustics is an emerging field that uses wildlife sound and sound production, and its relation to the environment, people, and other wildlife, to understand animal behavior as well as the impacts of human activity. Even species that we thought were silent are now being discovered to have a rhythm, a sound, and an acoustic form of communication. Recent revelations have included the recording noises of fish, plants, and reptiles. As environmental professionals, the production of sound by wildlife is a useful tool.

Many wildlife species are cryptic and difficult to detect. AJM performs a variety of surveys to detect mammal, bird, fish, and herpetofauna species in western Canada. In addition, we can use sound to detect, identify, and quantify wildlife species without ever observing them. Autonomous recording units (ARUs) are the acoustic equivalent of a wildlife game camera. They can be equipped with different kinds of microphones and adjusted to detect a broad range of acoustic signals. Moreover, these recording units are programmed with an autonomous recording schedule that records sound at different intervals and timing widows throughout the day. This allows for species to be detected passively without intensive human effort, over long periods, and during the night. Once sounds have been captured the next step is to analyze recordings.

It can take weeks to play back and listen to sound recordings, instead, what scientists do is they “look” at the sounds. At a glance, sound is made of energy waves emitted at different frequencies. Low sounds are emitted as low frequency, large sound waves, whereas high sounds are emitted at high frequencies as small sound waves. The intensity, rhythm, pitch, and duration of calls are just a few of the facets that contribute to the structure of a sound. Using specialized software, we can visualize each sound and analyze the different characteristics of a sound to determine what animal made the call. A spectrogram is a graphic used to visualize the spectrum of sound frequencies over time. Once a target sound or a frequency range is identified, the software can be automated to scroll through hours of data, flagging sounds that fall within the desired thresholds. Once flagged, sounds can be listened to and looked at to determine what species are present, provide abundance estimates, determine times of peak activity, and more. Analysis of acoustic recording is particularly useful in determining presence of bats, whose calls occur at frequencies higher than human ears are capable of hearing (ultrasound). Each species of bat produces locating calls at different ultrasonic frequencies and can be differentiated by automated software or by a sound analyst.

Sound recording technology can also be used underwater using hydrophones that detect and record water-borne sound waves.

This technology has been used to record whale songs, dolphin chatter, and even fish farts! Beyond species detection, acoustic technology can also be used to track and identify wildlife. Acoustic transponders are widely used in fisheries work where small transponders are implanted or attached to fish and marine species. These transponders communicate acoustically with base stations that pick up and interpret the specific signals sent by the transponders. As a management tool, sound is also used to deter wildlife. In Canada, bear bangers and deer/bird cannons are examples of the use of acoustic deterrents as management techniques. Scientists have also developed high frequency aquatic “pingers” that produce variable blasts of sound that alert dolphins, whales, and seals to the presence of large fishing equipment and deter them from capture and entanglement.

Across the world, use of sound is a valuable tool for conservation and management of wildlife. As more research is done, we also begin to understand that human-made sound has an impact. Species like birds, amphibians, and insects use sound to find and attract mates. In urban landscapes and in response to human-made sounds, some of the species are changing the characteristics of their calls to compete against the noise we produce. As a result, these individuals may be less successful in finding and attracting a mate as females are instinctually programmed to favour the original characteristics of their species’ calls. Marine noise has also been found to disrupt communication in whales and drive whales away from some habitats as they try to escape our noise pollution. In Alberta, grouse use sound to attract mates through log drumming and while on their dancing leks. During morning and evening periods, loud sounds in proximity to them may disrupt them and cause them to abandon these important sites.

With the impacts of human sound and activity on wildlife it is increasingly important to integrate sound recording and analysis as a tool for conservation and management, and to mitigate project impacts to wildlife. The team at AJM has personnel qualified as sound recordists and can interpret acoustic data to detect species of birds, amphibians, and bats. Whether it is a petroleum development project or the establishment of renewable energy production sites, if acoustic detection sounds like a good idea, it is! Contact us to learn more about the services we can provide.