When Nature Speaks: Discovering Species Through Sound
The team performs regular monitoring of the wetland during the summer months (Photo by Lanna Campbell/NCC staff)
Take a moment to step out into nature and listen to your surroundings. Do you hear the wind rustling the leaves? Can you hear the chirping birds or the croaking frogs? Can you hear water bubbling down a nearby stream, or insects buzzing in the air?
Listening to our surroundings can tell us important information about our environment and the species that live there. Nature Conservancy of Canada (NCC) staff and interns use listening to monitor nature reserves every spring, summer and fall. Their ears help them identify species that their eyes may not spot — species hidden in their natural habitat.
Two autonomous recording units were installed to monitor and document wetland species (Photo by Lanna Campbell/NCC staff)
“It’s important to know what’s going on at our nature reserves in order to manage them effectively,” explains Sophia Dalton, an NCC Conservation Intern in PEI. She and her supervisor, Hannah Kienzle, NCC’s stewardship coordinator for PEI, spent much of the summer monitoring nature reserves for signs of rare and invasive species. Last summer, however, their monitoring took them in a new direction.
In April, two autonomous recording units were installed on the Five Houses Woodland Nature Reserve in southeastern PEI. The autonomous recording units, also known as ARUs, pick up on more sounds if they are placed in a big, open space.
“Wetlands make for good sites for ARU use because they are fairly open,” says Hannah. Luckily, the Five Houses Woodland Nature Reserve features both freshwater wetlands and forest. The two ARUs were placed in two sections of wetland — one close to the road and the other farther into the nature reserve. The distance between the devices provided the team with the opportunity to compare the recordings. As wetlands are challenging to survey in person, the ARUs provide information that would have otherwise been difficult to collect.
Olive-sided flycatchers are attracted to dead or dying trees near open wetland areas (Photo by Steven McGrath)
The PEI team examined the recordings periodically over the summer months. Hannah’s and Sophia’s expertise were used to identify bird calls by ear. However, they had far too many recordings to go through each one individually. Luckily, software is available that can automatically identify bird species from recordings. For example, the Merlin app, created by the Cornell Lab, is designed to identify bird sounds. This software can be incredibly useful as a tool when used in combination with someone with experience in identifying bird calls.
From April to the end of July, 93 individual species had been identified on the nature reserve, 64 of which had never been seen or heard there previously. The ARUs recorded marsh birds, such as Virginia rail and sora, and frogs, such as spring peeper, green frog and northern leopard frog. Bat echolocation calls, which are too high-pitched to be heard by human ear, were also detected through an ultrasonic microphone. The team was able to lower the pitch of the recording to one eighth as well as the speed so they could hear the bats themselves.
Sophia’s favourite part of the experience was finding a section of a recording where eastern wood pewee, olive-sided flycatcher and Canada warbler could all be heard within a ten-minute segment. These three birds are all rare and at-risk species in PEI. It is incredible that there is evidence of them all on the nature reserve, let alone in a single short recording. The large number of species identified on the Five Houses Woodland Nature Reserve is solid evidence of the area's biodiversity.
A green frog emerges from its natural wetland habitat (Photo by Sean Feagan/NCC Staff)
“It’s important to protect under-represented habitats like wetlands because of how many species they support,” says Sophia, “especially in PEI, which is the smallest and most densely populated province.”
The success of this project shows that technology definitely has a place in nature conservation and monitoring. That said, ARUs and identification technology will not replace the work of humans.
“Either one alone is probably not enough to get a full picture,” says Hannah. Salamanders and newts, for example, cannot be heard on the recorders. In April, these species were identified by their eggs, which were found in small vernal pools.
This project was funded by the Prince Edward Island Wildlife Conservation Fund. The PEI team will share the data with other nature conservation organizations, such as the PEI Watershed Alliance and the Forests, Fish and Wildlife Division. They also have plans to begin installing ARUs on other wetland nature reserves across the province. Who knows what species they will find next?
