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Effects of Grazing and Burning on Densities and
Habitats of Breeding Ducks in North Dakota

Arnold D. Kruse¹ and Bonnie S. Bowen²
National Biological Service
Northern Prairie Science Center
Jamestown, ND 58401, USA

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Abstract: Native grassland communities controlled by public agencies become increasingly important to the maintenance of many wildlife species as privately owned grasslands are destroyed or degraded for farming, mining, and development. In turn, wildlife on publicly owned grasslands are affected by the management techniques practiced by local managers. We studied the effects of grazing and prescribed burning on upland-nesting ducks and the structure and type of vegetation from 1980 to 1988 at the Lostwood National Wildlife Refuge (NWR) in northwestern North Dakota. Mallard (Anas platyrhynchos), the most abundant species at Lostwood NWR, had lower (P < 0.05) annual nest densities on experimental and control herds in the later years than in the early years of the study. Spring burning reduced (P = 0.016) nest densities of gadwall (A. strepera). Spring grazing reduced nest densities of gadwall (P = 0.014), and blue-winged teal (A. discors, P = 0.023). Nest density of gadwall increased (P = 0.018) after spring grazing was terminated. On the summer burn/spring graze herds, blue-winged teal had lower (P = 0.010) nest densities after treatments (1987-88) than before treatments (1980-81). Nest success was high (mallard 34%, gadwall 45%, blue-winged teal 31%) but was not influenced (P >/= 0.16) by the burning and grazing treatments. During the study, the amount of grass/brush increased, whereas the amount of brush and brush/grass decreased on control and treatment herds. During the years with burning and grazing, short vegetation increased and tall vegetation decreased. On the spring graze herds, 1 year after grazing ended the vegetation was similar to that on the control herds. The spring burn and summer burn/spring graze herds recovered more slowly. Brushy species such as western snowberry (Symphoricarpos occidentalis) provided attractive nesting habitat for many upland nesting waterfowl species, especially mallard, gadwall, American wigeon (A. americana), and northern pintail (A. acuta). Habitat needs of additional species of wildlife that depend on grasslands may need to be considered when deciding how to manage habitat.

Key words: blue-winged teal, burning, ducks, gadwall, grazing, livestock, mallards, nest density, nest success, North Dakota, prairie management, waterfowl, wigeon.

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This resource is based on the following source (Northern Prairie Publication 0956):

Kruse, Arnold D. and Bonnie S. Bowen.  1996.  Effects of grazing and burning
     on densities and habitats of breeding ducks in North Dakota.  Journal of
     Wildlife Management 60(2):238-246.

This resource should be cited as:

Kruse, Arnold D. and Bonnie S. Bowen.  1996.  Effects of grazing and burning
     on densities and habitats of breeding ducks in North Dakota.  Journal of
     Wildlife Management 60(2):238-246.  Northern Prairie Wildlife Research 
     Center Online. 
     http://www.npwrc.usgs.gov/resource/birds/density/index.htm
     (Version 31JUL97).

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Table of Contents

• Introduction
• Study Site
• Methods
  • Grazing and Burning Treatments
  • Nest Searches
  • Analyses of Treatment and Year
  • Vegetation Structure
  • Vegetation Types
• Results
  • Nest Density
  • Nest Success
  • Vegetation Structure
  • Vegetation Types
• Discussion
  • Nest Density and Vegetation Structure
  • Nest Success
  • Vegetation Types
• Management Implications
• Acknowledgments
• Literature Cited

Tables

• Table 1. -- Number of nests and initiation dates for waterfowl at Lostwood National Wildlife Refuge, North Dakota, 1980-88.
• Table 2. -- Mean values of annual nest density (nests/ha) of 7 species of waterfowl at Lostwood National Wildlife Refuge, North Dakota, 1980-88.
• Table 3. -- Least-squares means of daily nest survival rate (DNSR) and Mayfield (%) estimate of nest success of 3 species of waterfowl at Lostwood National Wildlife Refuge, North Dakota, 1980-88.
• Table 4. -- Proportions of duck nests found in vegetation types and availability of vegetation types at Lostwood National Wildlife Refuge, North Dakota in 1981 and 1987.^a
• Table 5. -- Proportions of duck nests found in vegetation types and availability of vegetation types at Lostwood National Wildlife Refuge, North Dakota, 1980-88.

Appendices

• Appendix 1. -- Average burn times and grazing periods, grazing rates (animal unit months/ha, AUM/ha), and treatment schedules for each treatment at Lostwood National Wildlife Refuge, North Dakota, 1980-88.
• Appendix 2. -- Estimated differences and 95% confidence intervals (CI) for highest and lowest values of nest density and daily nest survival rate (nest success) for cases in which there was no effect of burning and grazing treatments, Lostwood National Wildlife Refuge, North Dakota, 1980-88.

Figures

• Figure 1. -- Total nest density (no. of nests during 1982-88 divided by the no. of upland ha) on treatment and control fields of 7 species of waterfowl at Lostwood National Wildlife Refuge, North Dakota.
• Figure 2. -- Annual nest density by treatment of 3 species of waterfowl at Lostwood National Wildlife Refuge, 1980-88.
• Figure 3. -- Distribution of visual obstruction reading classes (dm) in June for 3 burning and grazing treatments and control at Lostwood National Wildlife Refuge, North Dakota, 1980-88.
• Figure 4. -- Comparison of nesting use and availability of visual obstruction reading classes (dm) by 7 species of waterfowl at Lostwood National Wildlife Refuge, North Dakota, 1980-88.

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¹Present address: U.S. Fish and Wildlife Service, Wetland Habitat Office, 8711 37th St. SE, Jamestown, ND 58401, USA

²Present address: Department of Animal Ecology, Iowa State University, Ames, IA 50011, USA.

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