Northern Prairie Wildlife Research Center
Factors Limiting Mallard Brood Survival
in Prairie Pothole Landscapes
Gary L. Krapu1, Pamela J. Pietz, David A. Brandt, and Robert
Cox, Jr.*
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.
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).
Table of Contents
Tables and Figures
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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