Hi folks,

Thought that some of us might be interested in this article in the July, =
1996 issue of the Journal of Range Management relating to trampling of =
bird nests in different dairy pasture management situations:

Cattle trampling of simulated ground nests in rotationally grazed =
pastures. 1996. Laura Paine, D.J. Undersander, David W Sample, Gerald =
A Bartelt, and Tracy A Schatteman. J. Range Manage. 49: 294-300.

Abstract: "For many grassland songbird species, pastures represent some =
of the best available breeding habitat in the Upper Midwest. Increasing =
interest in intensive rotational grazing (IRG) among midwestern =
livestock farmers may result in an expansion of pasture hectares in the =
region. We evaluated the effects of several cattle stocking densities on =
ground nest survival in rotationally grazed cool-season pastures in =
southwestern Wisconsin. Ground nests were simulated with clutches of 3 =
unwashed pheasant eggs. We tested 3 rotational grazing systems: a 1-day =
dairy rotation stocked at 60 head per hectare; a 4-day beef rotation at =
15 head per ha; and a traditional, non-intensive 7-day rotation at 8 =
head per ha. Paddock size (1.2 ha) and nest density (15 nests per =
paddock) were held constant. The simulated nests were observed 4 times =
per day to document trampling patterns during the herds' diurnal grazing =
and rumination cycles. Trampling damaged a mean of 75% (+/- 3.1%) of the =
nests for all 3 treatments during 8 consecutive replications. While the =
7-day treatment exhibited a pattern of greater nest trampling during =
cattle grazing periods than during rumination periods, this pattern was =
less evident in the 4-day treatment and absent in the 1-day treatment. =
Increasing vegetation height-density and percent vegetation cover were =
associated with reduced nest trampling rates, but pasture forage =
production and removal were not associated with nest damage."


This simulation study might have application for pasture management in =
intensively-managed pastures in the Pacific Northwest as well, and gives =
an indication of just what sort of habitat is created when these "Five =
Acres and Independence" folks filling our rural lands take good farm =
ground and convert it into houses and 4 and a half acres of 'pasture' =
with a couple cows and a pony and..... The more hooves stepping around =
in the field, the more likely a nest is to be stepped on.

I don't know whether the dairy pasture management in western Washington =
and Oregon would come anywhere close to the nest effects reported here, =
because of the generally lower stocking rates involved. "Intensive" =
grazing is provides for healthier pasture grasses though than in =
year-round grazing, and with the amount of Ag land being converted to =
other uses ("developed"), a farmer has to make greater and greater use =
of the land that's left to him. Keep in mind, too, that 75% nest =
trampling is a whole lot better nest survival than that in a corn or =
broccoli field, or summer fallow in the wheat country. And it's a whole =
lot better than for ground-nesters in a Wal-Mart parking lot, or our own =
suburban/urban yards.

Just for the bovi-phobes among us :-) , here's a quote: "Other studies =
of ground nest trampling conducted on native rangeland in the western =
U.S. suggest a less clear-cut relationship between step density and nest =
trampling..."

Jon. Anderson
Olympia, Washington
festuca at olywa.net