10 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 72 



slightly higher temperature in girls than in boys, although the subjects 

 of experiment were too young to exhibit striking sexual differences. 

 Martins ^ notes a higher temperature in females than in males of the 

 domestic duck, and Simpson and Galbraith ^ make similar observa- 

 tions with regard to other birds in those cases in which the sex of 

 the individuals in hand was known at the time of experiment or was 

 determined later by dissection. A few observations made by Hilden 

 and Stenback '' do not bear this out, as they cite higher temperatures 

 in males than in females. Apparently these authors misunderstood 

 Simpson and Galbraith as they state that these observers also record 

 higher temperatures in males than in females although the reverse 

 is true. 



In my own observations there is found in some species a convinc- 

 ing agreement with the findings of Simpson and Galbraith, Martins 

 and Roger in this matter, as where a sufficient amount of data is avail- 

 able the average temperature of the female is usually slightly higher 

 than that in the male. Certain exceptions to this rule will be noted 

 later. The difference in favor of the female where present is rather 

 slight, being usually only a part of a degree. Thus in the green- 

 winged teal (Ncttion carolinensc) the temperature of the male (19 

 records) averaged 106.1°, of the female (8 records) 106.6°, a differ- 

 ence of .5° in favor of the female. In Traill's flycatcher (Empidonax 

 trailli) males (6 records) averaged 108.0° and females (4 records) 

 108.6° a difference of .6°. Numerous other instances will be noted 

 in table 3 but need not be cited here as the two given will serve to 

 exemplify the statement made above. 



The present work, however, has emphasized the fact that in cer- 

 tain groups the temperature of the male on the average is distinctly 

 higher 'than in the female. Apparently this is true in the herons 

 (Ardeidae) as in three species in that group we have the following 

 averages: Great blue heron (Ardea herodias) male (2) 104.8°, 

 female (2) 103.7° ; snowy heron (Egretta candidissima) male (5) 

 104.8°, female (8) 104.0° ; and black-crowned night heron (A^ychVora.*- 

 naevius) male (3) 103.5° ^-^d female (2) 102.6°. A similar differ- 

 ence is best shown perhaps in certain of the shore-birds, as the phal- 

 aropes, where it is indeed striking. In the northern phalarope 

 (Lobipes lobatus) males (9 records) averaged 107.6° and females 

 (17) only 106.6°. Males (10) of the Wilson's phalarope (Sfegano- 

 pus tricolor) gave 106.3°, and females (18) only 105.7°. The same 



'Journ. de Phys., 1858, p. 19. 

 ^ Journ. of Phys., 1905, p. 237. 

 ^ Skandinavischcs Arch, fiir Phys., Bd. 34, 1916, pp. 382-413. 



