Cattle Trampling of Simulated Ground Nests in Rotationally Grazed Pastures

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 (lRG) among midwestem 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 graz.ed cool-season pastures in southwestern Wisconsin. Ground nests were simulated with clutches of 3 unwashed pheasant eggs. We tested 3 rotational grazing systems: a l-day dab-y rotation stocked at 60 bead ha-'; a 4-day beef rotation at 15 bead by?; and a traditional, non-intensive 7-day rotation at 8 bead ti*. Paddock size (1.2 ha) and nest density (15 nests paddock') were held constant. The simulated nests were observed 4 times day-' to document trampling patterns during the herds' diurnal graz*mg and nunination 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 4day treatment and absent in the l-day treatment. Increasing vegetation beigbtdensity and percent vegetation cover were associated witb reduced nest trampling rates, but pasture forage production and removal were not associated with nest damage.

An Evaluation of Canada's Permanent Cover Program: Habitat for Grassland Birds?

“…Of the four species more frequently associated with hayland than pasture in this study, Clay-colored Sparrow and Savannah Sparrow are experiencing significant population declines (Sauer et al 1999). While species associated with pasture are not vulnerable to direct threats such as haying (but see Paine et al 1996), heavily grazed pastures likely do not provide habitat for species that prefer intermediate or tall vegetation height and density. The influence of vegetation on bird community composition shown in this study and others, indicates habitat maintained in a mosaic of successional stages will provide habitat for the richest diversity of grassland species.…”

Livestock grazing affects the egg size of an insectivorous passerine

“…Hypothesis 1 (H1) is that livestock grazing could affect bird reproduction through the direct effects of disturbance and trampling (Paine et al 1996). In this case, we would expect to see an increase in total nest failures and lower breeding success as grazing pressure increased.…”

Effect of cattle trampling on ground nesting birds on pastures: an experiment with artificial nests

“…They consisted in small (≈10 cm) radius cavities hosting four snail shells of Helix pomatia standing for the average number of eggs in a clutch (Ottvall 2004). Empty snail shells were preferred to eggs as in Paine et al (1996) or Bareiss et al (1986) to avoid predation by foxes or crows, for example, and focus on the effect of trampling. The need to conduct a daily survey of nests prevented us from using buried clay discs as in Mandena et al (2013) as these could not have been checked every day.…”

“…Many studies have tried to quantify trampling effects (e.g. Bareiss et al 1986;Paine et al 1996;Pavel 2004) but until now, no study had recorded the dynamics of trampling to test if this hypothesis of independence was a good approximation of reality.…”