Some Adaptations of Marsh-Nesting Blackbirds

by Orians, Gordon H.

• ISBN13: 9780691082370
• ISBN10: 0691082375
• Format: Paperback
• Copyright: 1980-04-01
• Publisher: Princeton Univ Pr

Summary

The variety of social systems among the New World blackbirds (Family Icteridae) and the structural simplicity of their foraging environment provide excellent opportunities for testing theorics about the adaptive significance of their behavior. Here Gordon Orians presents the results of his many years of research on how blackbirds utilize their marsh environments during the breeding season. These results stem from information he gathered on three species during ten breeding seasons in the Pacific Northwest, on Red-winged blackbirds during two breeding seasons in Costa Rica, and on three species during one breeding season in Argentina. The author uses models derived from Darwin's theory of natural selection to predict the behavior and morphology of individuals as well as the statistical properties of their populations. First he tests models that predict habitat selection, foraging behavior, territoriality, and mate selection. Then he considers some population patterns, especially range of use of environmental resources and overlap among species, that may result from those individual attributes. Professor Orianns concludes with an overview of the structure of bird communities in marshes of the world and the relation of these patterns to overall source availability in these simple but productive habitats.

Author Biography

Gordon H. Orians is Professor of Zoology and Director of the Institute for Environmental Studies at the University of Washington.

Table of Contents

Preface	p. vii
The Approach and the Subjects	p. 3
The Players	p. 3
The Theater	p. 8
Materials and Methods	p. 18
Marshes as Providers of Resources for Blackbirds	p. 25
Quantity of Emergence	p. 26
Temporal Pattern of Emergence	p. 34
Abundance of Insects on the Uplands	p. 42
The Adaptations: Selection of Habitats, Territories and Mates	p. 48
Habitat Selection by Males	p. 50
Habitat Selection by Females	p. 53
Predictions and Tests about Habitat and Mate Selection	p. 56
Sizes of Territories	p. 73
The Cues Used by Blackbirds in Selecting Their Territories	p. 80
Conclusions	p. 86
The Adaptations: Foraging Behavior	p. 90
Theory	p. 91
Tests of Foraging Theory	p. 102
Tests of CPF Theory	p. 131
Conclusions	p. 138
The Patterns: Variability in Use of Resources	p. 141
Range of Lake Productivity Occupied	p. 141
Range of Nest Sites Occupied	p. 149
Breeding Seasons	p. 153
Clutch Sizes	p. 155
Variability in Foods and Foraging	p. 159
Conclusions	p. 171
The Patterns: Competition, Overlap and Community Structure	p. 173
Short-Term Effects of Competition	p. 174
Long-Term Effects of Competition	p. 186
Competition and Size	p. 189
Adaptations Among Argentine Marsh-nesting Blackbirds	p. 194
The Species of Blackbirds Breeding in Argentine Marshes	p. 195
Foods and Foraging	p. 210
Patch Utilization While Foraging	p. 216
Dietary Breadths	p. 222
Competition and Overlap	p. 222
Of Birds and Marshes	p. 226
Significance of Marsh Structural Simplicity	p. 226
Nonpasserine Birds in Marshes	p. 239
Avian Social Systems in Marshes	p. 241
Island Biogeography of Marshes	p. 242
Effects of Blackbird Predation on Odonate Populations	p. 244
Conclusions	p. 251
General Conclusions	p. 253
Appendixes	p. 255
References	p. 275
Index	p. 291
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