The Effects of Cattle Grazing on Wetland-dependent Birds in the Aspen Parkland

This information is adapted from a poster presentation created by Robb.

Introduction

Alberta is host to approximately 5.7 million cattle, and cattle numbers are expected to increase drastically in the future. The potential impacts to waterfowl include:

• Reduced species diversity
• Reduced attractiveness of nesting cover
• Reduced nest success

Robb's objective was to investigate the diversity, relative abundance, and nest success of wetland-dependent birds in relation to grazing intensity on adjacent lands. He also investigated the relationship between grazing intensity in the uplands and the impact on emergent vegetation communities.

Study Area

The study area included 90 wetlands within 45 quarter sections between Tofield and Pine Lake, Alberta. This area of Aspen Parkland responds well to rainfall, allowing intensive grazing. The pastures included native/naturalized and tame pastures, which were separated into six categories of grazing intensities:

• Native idle or lightly grazed
• Native moderate
• Native heavy
• Tame idle or lightly grazed
• Tame moderate
• Tame heavy

Methods

• Point count surveys to measure species diversity and abundance relative to grazing intensity
• Nest searching and nest fate monitoring to evaluate nest success relative to grazing intensity
• Vegetation surveys across wetland fringes
• Relate grazing intensity within wetlands to area of wetland habitat within pastures
• Landowner surveys to identify stocking rates, cattle types, grazing duration, and the use of off-site watering and salting facilities

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