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

Making a Home in a Disturbed Landscape

Which species are winners or losers when mining stops?

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

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.

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.

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.

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