A century ago Canada began developing its oil sands, bitumen-rich deposits underneath the Western heartland of Alberta, and since then towering facilities have popped up all over the once-flat grassland landscape.
According to new research, these alien structures (as far as nature is concerned, anyway) are allowing a "parasitic" species of bird to thrive, a development that could cause undue stress on other other native species, including the Savannah sparrow.
The brown-headed cowbird is native to Alberta, and survives by sneaking its eggs into the nests of other birds. This is because cowbirds, by some cruel trick of evolution, are unable to make their own nests. Once they hatch, baby cowbirds tend to be hungrier, bigger, and louder than the birds they share a nest with, and may even kill their brood-mates. Historically, cowbird "brood parasitism," as it's called, was kept in check because cowbirds like resting on an elevated surface. Roaming bison once served this purpose, and the cowbirds would perch on their backs and wander with them, never staying in one place long enough to have much of an impact on the local bird population.
Times have changed, though, and cowbirds have new and more stable places to perch and scope out victims: on top of oil sands infrastructure.
According to a new study published last week in Royal Society Open Science, cowbird brood parasitism rates for Savannah sparrow nests are four times higher around oil sands infrastructure than in nests further away. The study notes that the Savannah sparrow population in Alberta is currently decreasing by 1.3 percent annually.
"The increase is so large that, for species that are declining, it could have a negative impact on their productivity in areas that have a lot of oil and gas development," said Nicola Koper, a professor at the University of Manitoba Natural Resources Institute and co-author of the paper, over the phone. "It was quite shocking."
The data in the paper was collected in 2013 and 2014, but Koper said the team has continued to observe the area and the trend has been consistent. According to her, the paper's observations regarding the impact of brood parasitism for Savannah sparrows could be indicative of what's happening with other species in the region, too.
Importantly, she noted, cowbirds alone aren't going to drive a species to endangerment or even extinction, but it's one more conservation challenge to deal with.
"The problem is that there are cumulative impacts," Koper said. "There are impacts from habitat loss, noise in the environment, and this additional stressor is one more thing that drives these populations to decline."
According to Koper, one solution to the problem of brood parasitism might be to minimize the amount of oil infrastructure that sits above the ground in Alberta, offering cowbirds fewer places to perch.
Until something is done, though, it's likely that cowbirds will continue to prey on the songbirds of the prairies, with no benefit to other species.
"Well, it'll be good for the cowbirds," Koper said.