Friday, May 22, 2009

Grass, Sky, Song Illustrated:
"Landscape Pathology 101"

this McCown's Longspur image courtesy of Alan MacKeigan

McCown's longspur was one of my favourite prairie birds to see in cropland near Regina. Until the late 1990s there were still one or two reliable places where I could find them nesting within ten or fifteen minutes of the city. In this chapter of Grass, Sky, Song, I talk about their disappearance, and the decline of the once abundant horned lark on the Regina plains. Many factors have contributed to the loss of these birds, but one that does not get talked about near enough is the transformation in agricultural practices during the last twenty years, coinciding with the decline of these and other birds.

Big rigs like this are becoming the norm in prairie Canada, as farmers get bigger and adopt the more intensive practices of direct seeding and what is called "conservation tillage". Instead of leaving land fallow and tilling it to control weeds, most producers now seed directly in last year's stubble and control weeds with heavy applications of herbicides. Land seldom gets a rest from year to year. Birds such as the horned lark and McCown's longspur were once able to breed in summerfallow, but no longer have that option.

horned lark image courtesy of Val Thomas

Horned larks will still attempt to breed in stubble now but the timing of the farmer coming to seed in the spring means that many of their nests are destroyed by the passage of massive seed drills pulled behind four-wheel drive tractors. Thus, what was once fair breeding habitat for the species has now become an ecological trap. Breeding Bird Survey data for Saskatchewan show a yearly decline of 5.6 percent. In Manitoba, the decline is steeper, at 7.83 percent per year.

But that is only part of the effect of the change to these new practices.
The larger farm equipment became under the transition from tillage (summerfallowing) practices to "conservation tillage," the more difficult and expensive it became for farmers to leave margins around the edges of their fields or around sloughs and bush. This has meant that fields today are "cleaner," and in general contain less grassy habitat on their edges and fewer sloughs and aspen bluffs. All of this edge habitat once provided nesting and foraging areas for more tolerant grassland birds that once survived on the margins of cropland--birds such as kildeer, western meadowlarks, savannah sparrows, Le Conte's sparrows, and many others. Farmers don't choose these new practices because they want to destroy nature in and around their fields, but end up being drawn in to a cost-price squeeze that pushes them toward a scale and style of farming that in the end is hostile to any plant or creature that does not directly contribute to crop yield. Here is a web page from the Alberta Government's Agriculture and Rural Development department, advising farmers who use these "conservation tillage" or "no till" systems on how they can poison all the ground squirrels, gophers, voles and mice on their land. Birds can be a problem (starlings and blackbirds are mentioned) but, mercifully, there are no recommendations on how to "control" them.

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