1911-12.] Body Temperature of Diving and Swimming Birds. 19 
V. — Observations on the Body Temperature of some Diving 
and Swimming Birds. By Sutherland Simpson, M.D., D.Sc. 
(From the Physiological Laboratory, Medical College, Cornell Uni- 
versity, Ithaca, N.Y., U.S.A.) 
(MS. received October 10, 1911. Read November 20, 191 1.) 
CONTENTS. 
PAGE 
I. Introduction . . . . . . . . . .19 
II. Previous Observations on the Subject . . . . .20 
III. Methods adopted in Present Investigation . . . . .23 
IV. Results and Conclusions ....... 32 
V. Summary .......... 35 
I. Introduction. 
The observations recorded in the following pages were begun as far 
back as 1903, and at that time the intention was to investigate the influ- 
ence which the different seasons of the year may have on the body 
temperature of warm-blooded animals. With the exception of the group 
of hibernating animals, birds appear to show more distinct and definite 
seasonal changes in their habits and bodily activities than mammals, and 
for this reason they were chosen as the most suitable subjects for the 
inquiry. 
Naturally one would expect that any seasonal rhythm which might be 
present would be more evident in wild than in domesticated birds, the 
latter being shielded from the rigours of climate, and living all the year 
round in surroundings more or less artificial ; and as several species of 
marine birds, which are very numerous in northern waters, are non-migratory 
and comparatively easily secured, it was planned to make one series of 
observations on these in the mating and breeding season, during the months 
of March and April, and another set in August and September when the 
birds are moulting. 
Various circumstances arose, however, which made it impossible to 
carry out the original plan, still, many observations have been made in the 
course of four or five years and the records collected ; and since com- 
paratively little is known regarding the body temperature of several of the 
species examined, it may be of interest to some to give these records 
publication as they stand. 
