Forced Submersion and Circulation

Abstract

Considering the ready accessibility of the domestic mallard, it is not surprising that it was the first subject of study of forced submersions. It is also a curious twist that the domestic mallard is derived not from a diving duck, but a dabbler, a species that feeds just below the surface in puddles, shallow ponds, or small streams. So much of our first information, as well as a good deal of later data on “diving” physiology, first came from a nondiver. Yet, for unknown evolutionary reasons this bird has remarkable tolerance to asphyxia, and has provided a considerable body of useful information about asphyxial reflexes. An extensive review of the contribution duck studies played in assessing asphyxial defense responses is presented by Andersen (1966), an investigator who himself made a significant impact on diving physiology by studying the domestic mallard. The review of Andersen has now been extended considerably by others, and Jones and Furilla (1987) in particular have presented a broader review on birds, but still with emphasis on the domestic mallard. In this work many of the ideas dealt with are discussed in this and later chapters.