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Factors Limiting Mallard Brood Survival
in Prairie Pothole Landscapes

Gary L. Krapu¹, Pamela J. Pietz, David A. Brandt, and Robert Cox, Jr.*

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Abstract: In order to estimate mallard (Anas platyrhynchos) production from managed and unmanaged lands, waterfowl biologists need measurable predictors of brood survival. We evaluated effects of percent of seasonal basins holding water (WETSEAS), percent of upland landscape in perennial cover (PERNCOVER), rainfall (RAIN), daily minimum ambient temperature (TMIN), hatch date (HATCHDATE), brood age (BA; 0-7 or 8-30 days), age of brood females, and brood size on mallard brood survival in prairie pothole landscapes, and developed a predictive model using factors found to have significant effects. Sixteen of 56 radiomarked broods experienced total loss during 1,250 exposure days. Our final fitted model of brood survival contained only main effects of WETSEAS, HATCHDATE, and RAIN. Total brood loss during the first 30 days of exposure was 11.2 times more likely for broods hatched on areas with <17% WETSEAS than those on areas with >59% WETSEAS. Total brood loss was 5.2 times more likely during rainy conditions than during dry periods, and the hazard of total brood loss increased by 5% for each 1-day delay in hatching between 17 May and 12 August. High survival of mallard broods in landscapes where most seasonal basins contain water underscores the importance of maintaining seasonal wetlands as a major component of wetland complexes managed for mallard production. Because early hatched broods have higher survival, we also suggest that waterfowl managers focus their efforts on enhancing nest success of early laid clutches, especially in wet years.

Key words: Anas platyrhynchos, brood survival, hatch date, mallard, model, perennial cover, predation, Prairie Pothole Region, rainfall, recruitment, seasonal wetlands, temperature.

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This resource is based on the following source (Northern Prairie Publication 1086):

Krapu, Gary L., Pamela J. Pietz, David A. Brandt, Robert R. Cox, Jr.  2000.
     Factors limiting mallard brood survival in prairie pothole landscapes.
     Journal of Wildlife Management 64(2):553-561.

This resource should be cited as:

Krapu, Gary L., Pamela J. Pietz, David A. Brandt, Robert R. Cox, Jr.  2000.
     Factors limiting mallard brood survival in prairie pothole landscapes.
     Journal of Wildlife Management 64(2):553-561.  Jamestown, ND: 
     Northern Prairie Wildlife Research Center Online.  
     http://www.npwrc.usgs.gov/resource/birds/brdland/index.htm  
     (Version 21JUL2000).

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Table of Contents

• Introduction
• Study Areas
• Methods
  • Field Procedures
  • Explanatory Variables
  • Data Analysis
• Results
• Discussion
  • Effect of Seasonal Ponds
  • Effect of Rainfall
  • Effect of Hatch Date
• Management Implications
• Acknowledgments
• Literature Cited

Tables and Figures

• Table 1
• Figure 1

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¹ E-mail: gary_krapu@usgs.gov
^* All Authors: U.S. Geological Survey, Northern Prairie Wildlife Research Center, 8711 37th Street SE, Jamestown, ND 58401, USA

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