In this groundbreaking scientific study, W.H. Bergtold offers a comprehensive analysis of the incubation periods of a wide variety of bird species. Drawing on data collected over many years of research, Bergtold provides a detailed account of how different factors-such as temperature, humidity, and nesting habits-can affect the length of an egg's incubation period. The book also includes many fascinating observations about the behavior and physiology of various bird species, and offers insights into the evolutionary processes that have shaped their reproductive biology. This is an essential resource for anyone interested in avian biology, or in the broader field of evolutionary biology. This work has been selected by scholars as being culturally important, and is part of the knowledge base of civilization as we know it. This work is in the "public domain in the United States of America, and possibly other nations. Within the United States, you may freely copy and distribute this work, as no entity (individual or corporate) has a copyright on the body of the work. Scholars believe, and we concur, that this work is important enough to be preserved, reproduced, and made generally available to the public. We appreciate your support of the preservation process, and thank you for being an important part of keeping this knowledge alive and relevant.

Excerpt from A Study of the Incubation Periods of Birds: What Determines Their Lengths? In the course of certain studies in ornithology, more particularly avian physiology, undertaken by the author several years ago, it early became apparent that the factors fixing or determining the length of the incubation period with different birds was largely, if not wholly, unknown. The following pages give the results of a prolonged and detailed study of this phase of bird physiology. The author regards all zoologic classification as a means, not an end; the classification adopted in this work is merely a means of facilitating the handling of a mass of data full of contradictions and uncertainties, and the selection of this particular bird classification was governed by a question of expediency only; obviously the author in no way wishes to be understood as believing this classification to be the best, or the only one. The author believes, however, that this classification is an up-to-date reflection of our present knowledge of the relation of vario'us birds to each other. It is inevitable that mistakes of various sorts will be found in this book; in extenuation of such errors the author trusts that his critics will recall that the labor involved in the investigations reviewed in the following pages was one of love, and carried on in the spare moments of a fairly busy professional life. A brief resume of pages 43 to 76 of this book was read before the Annual Meeting of the American Ornithologists' Union at Philadelphia, November 15, 1916. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.

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