Breeding Population Inventories and Measures of Recruitment
Lewis M. Cowardin and Robert J. Blohm
I. Introduction
In this chapter we review the techniques used to measure two important parameters of waterfowl populations, size of breeding population and recruitment. If waterfowl are to be managed toward goals defined in terms of population sizes such as those in the recently signed North American Waterfowl Management Plan (U.S. Fish and Wildlife Service [USFWS] and Canadian Wildlife Service [CWS] 1986), there must be some measure of population size for the various species. Waterfowl managers usually measure population size during the breeding season, although for some species and in some areas winter inventories may be used. Population size is a function of natality and mortality. Other chapters in this volume deal in detail with the biology of those processes. This chapter discusses procedural aspects of measurement and reviews some of the operational systems that have been used to estimate population size and recruitment, especially in North America.
This resource is based on the following source:
Cowardin, Lewis M., and Robert J. Blohm. 1992. Breeding population inventories.
and measures of recruitment. Ecology and Management of Breeding Waterfowl.
University of Minnesota Press, Minneapolis, MN. Chapter 13:423-445.
This resource should be cited as:
Cowardin, Lewis M., and Robert J. Blohm. 1992. Breeding population inventories.
and measures of recruitment. Ecology and Management of Breeding Waterfowl.
University of Minnesota Press, Minneapolis, MN. Northern Prairie Wildlife
Research Center Online.
http://www.npwrc.usgs.gov/resource/birds/ecomanag/chap13/chap13.htm
(Version 02FEB99).
Table of Contents
- Introduction
- Definitions
- Breeding Population
- Recruitment
- Uses of Population Estimates
- Goals and Ogjectives
- Population Trends
- Evaluation of Habitat
- Harvest Management
- Uses of Measures of Recruitment
- Evaluation of Habitat
- Harvest Management
- Population Models
- Differences in Scale
- Species Differences
- Definitions
- Population Estimates
- The Biological Basis of Estimators
- Obtaining the Count
- Ground Counts
- Counts from Aircraft
- Counts from Aerial Photography
- Indices to Breeding Population
- Estimates Based on Habitat Availability
- Indirect Estimates Based on Mathematical Models
- Measures of Recruitment
- Definitions
- Estimates and Indices
- Pair and brood Counts
- Nesting Studies
- Radiotelemetry
- Social Index
- Late Nesting Index
- Methods Based on Fall Age Ratio
- Sampling
- Examples
- Selecting a Method
- The Future
- Conslusions
- References
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