Tuesday, June 22, 2010

Breeding Bird Survey where there once was grass

Breeding Bird Survey point on cropland near Francis, Saskatchewan

On the weekend Karen and I did the Tyvan Breeding Bird Survey (BBS) and later this week, if the weather holds, my son Jon and I will head to Crooked Lake to do another one.

On Saturday morning there was no wind or rain to interfere with the chorus of birds along the 25 mile route across cropland in the Upper Wascana Creek drainage. The BBS, said to be the most important citizen science effort on the continent, has been going since 1966. The effort depends almost entirely on the ear-birding skills of amateurs, who are dispatched to pre-determined routes in breeding season to record the presence of birds by stopping to listen for three minutes at 50 stops a half-mile apart.

With all the rain this year there were wetlands everywhere on the first part of the Tyvan route. Ducks and other wetland birds were in good numbers and I was especially happy to hear so many American Bitterns, a bird that the BBS shows is declining over much of its range. I haven't tallied the results yet but I think I heard somewhere between 8 and 11 bitterns in the first 14 stops. Trouble is, the bittern's slough-pump, "ha-runk-a-dunk" call can be heard at least a mile away if things are quiet. So I was never quite sure if I was hearing the same individual at two consecutive survey stops.

American Bittern image courtesy of Wikimedia Commons

The Tyvan--Francis area ranges from gently rolling moraine to level glacial lake bed. I would estimate that more than 90% of the land is cultivated and so there is not a lot of grassland on the route but plenty of erstwhile grassland now growing grain, canola, lentils, and peas. The most common grassland birds are horned larks. . .

image courtesy of Val Thomas

Savannah Sparrows. . .

Vesper Sparrows. . .

Bobolinks. . .

Western Meadowlarks. . .

and Upland Sandpipers.

Some of the upland sandpipers seemed to be singing and flying over cultivated fields and horned larks were in cropland with short vegetation. Savannah and Vesper Sparrows were at almost every stop as long as there were open landscapes of some kind. The meadowlarks were in places where there is either hay land, native pasture (only three or four of the fifty stops), or cropland with grassy margins. I found bobolinks only at two or three stops where the grass was high enough, usually near a wetland.

At the end of the route, for the last ten stops or so, I am in a landscape that looks like a wasteland--nothing but crop running off to all horizons and almost no grass at the edges. Here is a typical view of these level, empty fields.

The emptiness is all the more pronounced by the paucity of birds. At each of these last stops, I typically count nothing but a couple of Savannah Sparrows and Horned Larks, with perhaps a passing gull or Brown-headed Cowbird.

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