Written by Clara Reid, Avian Field Intern, and Chris Coxson, Avian Field Technician, both with the Northern Boreal Mountains Program based in Whitehorse, Yukon. 

Yellow Warbler, found in shrubby habitats in unmined areas and revegetated placer mines. Photo: Chris Coxson 

The word “mining” brings certain images to mind: noisy and large machinery, piles of rocks and overturned trees, and stripped away vegetation. These may seem like hostile conditions for wildlife such as nesting birds, but what happens after the mining stops and the dust settles? As vegetation regrows, some bird species may flourish in an old mine while others that were there before mining may not re-establish. Which species are winners or losers in this new environment, and how long does it take for them to return? 

This summer, our field crew set out to answer this question in central Yukon near the communities of Dawson City and Mayo. We were looking specifically at placer gold mining, a practice that is common in the region and involves excavating creek valleys to retrieve gold from buried gravel layers. This project is being led by Morgan Brown, Breeding Bird Cumulative Effects Post-Doctoral Fellow, and Chrystal Mantyka-Pringle, Co-Director of WCS Canada’s Northern Boreal Mountains Program. The work is being carried out in collaboration with Tr’ondëk Hwëch’in and Nacho Nyak Dun First Nations. Results from this research will inform regional land use planning, by helping to better understand the cumulative effects of disturbance on the landscape.  

The study region is a landscape of hills blanketed by boreal spruce forest, with discontinuous permafrost beneath and wetlands dotting the lowlands. Placer mining leaves valleys looking very different from adjacent unmined riparian areas. Depending on mining and reclamation practices and the amount of time since a mine has been active, mined sites may be piles of bare rock, open shrubland, or thick deciduous vegetation interspersed with marshy settling ponds. In comparison, habitats near creeks that have not been mined encompass a diverse mix of carbon-rich wetlands, floodplains and forested hillsides. By comparing the habitat conditions and bird activity in mined sites of various ages to those at sites near unmined creeks, we hope to better understand how placer mining affects where birds make their homes.  

Unmined landscape west of Dawson City. Photo: Chris Coxson 

A mined landscape in Hunker Creek Valley, southeast of Dawson City. Photo: WCS Canada 

Our field crew assessed bird communities across these habitats using sound recorders called ARU’s (autonomous recording units) and in-person point counts (standing in one spot while looking and listening for birds). Nothing can replace standing in the chilly early morning air with dew-soaked pants, intently focused on bird songs from all directions. However, ARU’s can be deployed for weeks at a time and thus enable us to collect more data and detect species we may otherwise have missed. Our crew placed ARU’s at dozens of sites across central Yukon, collecting hours of recordings which will be transcribed in the fall to produce bird diversity data.  

Sound recorder (ARU) in a previously mined site near Mayo. Photo: WCS Canada 

We visited many placer mines, navigating washed out roads and the boot-sucking mud of settling ponds. On mined sites revegetated in the last few years, grass and shrub habitats often hosted Savannah or Lincoln’s Sparrows singing atop low bushes. On older sites we pushed through dense tangles of willow and alder, home to sweetly singing Yellow Warblers. On some decades-old sites, young mixed forest produced a rich morning chorus including Fox Sparrows, Swainson’s Thrushes and Yellow-bellied Flycatchers. Sometimes we would stumble upon ponds home to families of ducks, or shorebirds such as Spotted Sandpipers and Lesser Yellowlegs very loudly advising us to leave the vicinity of their nests immediately. 

Savannah Sparrow, found in open grassy habitats with low shrubs in recently revegetated mines. Photo by Chris Coxson 

Swainson’s Thrush, found in mature coniferous forest and younger mixed-wood forest in sites mined decades ago. Photo by Chris Coxson 

Spotted Sandpiper adult, found near open water.  Photo by Chris Coxson 

Spotted Sandpiper nest in revegetated mine on Sulpher Creek. Photos by Chris Coxson 

Unmined riparian sites were harder to get to. Though some were accessible by hiking from the road, our search led us to a highlight of the season – helicopter accessed sites. Being surrounded by large spruce and sphagnum-filled wetlands was quite pleasant, and it turns out that exiting a helicopter into knee-deep water is refreshing on a 30°C day! At our unmined sites we encountered many species familiar to us from mined sites, but also new ones such as Spruce Grouse, Townsend’s Warblers and Hammond’s Flycatchers. As we flew over the Dawson City area and observed extensive machinery trails crisscrossing the hills and mines in many creek valleys, we were reminded of the urgent need to understand how these disturbances are affecting ecosystems, and how we can act to reduce their negative impacts.

Chris Coxson hard at work in an unmined riparian site. Photo: Morgan Brown 

Helicopter coming to pick up field staff near a riparian site west of Dawson City. Photo: WCS Canada 

This summer’s field season was not without challenges. On our first field day, flooding closed the road to the Dawson City area where most of our field sites were, separating crew members for almost a week. Those who could rerouted and headed to sites near Mayo instead. Later, we ran into challenges safely accessing mining claims, which are a mosaic of active and inactive mining operations run by many small companies. An intense windstorm also threw us for a loop when a tree fell on one of our work trucks. We relied on the flexibility of our team to keep going, and are thinking of better ways to approach things next year.  

Our work truck had a tree fall on it in a campground during a storm. Photo: Clara Reid 

This year’s birdsong chorus is now over, replaced by warning calls from parents as their fledglings find their wings. For our crew, soon it will be time to sit down and figure out which bird species ventured into mines of various ages to make their homes, and which ones preferred unmined habitats. When snow blankets the ground and the forest is quiet, staff will be cozy indoors listening to ARU recordings, relishing in cheerful spring birdsong. 

Clara Reid (left), Morgan Brown (middle) and Chris Coxson (right) planning which sites to tackle the following day. Photo: Chrystal Mantyka-Pringle