Literature Cited:
Behavioral Ecology 1991, 2 : 69-76
The Condor: Vol. 97, No. 1 (Feb 1995) 50-56
The Condor: Vol. 81 : 72-77
Ornithology 3
rd
Edition, Frank B. Gill, Nest Sanitation 446
All Avian Photographs:
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Adrian & Jane Binns