The Dipper (Cinclus mexicanus) and the water shrew (Sorex palustris) are the smallest true divers in their classes. These species are being studied with regard to the questions: 1) What is the relationship of diving endurance to body size? 2) Are the physiological responses to diving by the small homeotherms similar to those which have been well-described for the larger divers? Project Number 144.
Calder, William A.
"Physiology of Diving and Breath-holding in Small Birds and Mammals,"
Jackson Hole Research Station Annual Report: Vol. 1967
, Article 6.
Available at: http://repository.uwyo.edu/jhrs_reports/vol1967/iss1/6