NO. 12 BODY TEMPERATURE OF BIRDS — WETMORE 7 



western Florida, gave temperatures of ioi.8° and 102.7° respectively. 

 A second male shot an hour later registered 100.7°. These birds 

 had been resting quietly for the entire day. In direct contrast is the 

 condition found in a male killed by moonlight at 8.15 p.m. in the 

 Chiricahua Mountains in southeastern Arizona. On this evening 

 screech owls had been actively calling for over an hour before this one 

 was secured. The bird taken had a temperature of 105.4°. A female 

 secured in the Dragoon Mountains, Arizona, at 8.45 a. m., not long 

 after it had retired for the day, registered a body heat of 105.3°. 

 In the case of those species active during the hours of daylight the 

 difference is less marked, due in large part to the fact that the majority 

 of birds examined had been killed during the period of their normal 

 activity when little or no temperature range was evident that could 

 be correlated directly with time. However, it is possible to cite a few 

 cases showing this regular variation. 



The series of mourning doves {Zcnaidura macroura) obtained may 

 be discussed as pertinent in the matter of diurnal variation in birds 

 of diurnal habit. In four males secured between 5.00 a. m. and 

 5.45 a.m., the range in temperature is from 108.0° to 109.8°, the 

 four records giving a mean of 108.9°. Five other birds shot between 

 5.00 p. m. and 6.00 p. m. under similar conditions give a variation of 

 from 109.3° to 110.4° with a mean of 109.6°. An average difference 

 of .7° is thus shown. All of these birds were feeding but in the first 

 set killed early in morning the body heat was still comparatively low. 



As stated above, most of the records were secured at hours when 

 the temperature was naturally high so that little time variation is 

 shovvoi. However, the following may be quoted in addition to the 

 above. An ash-throated flycatcher (Myiarchiis cinerascens) taken at 

 7.30 a. m. had a temperature of 108.6°. Another taken at 10.00 a. m. 

 registered 110.0° and a third shot at 11.00 a. m. showed a body tem- 

 perature of 111.8°. All of these birds were males. A male Canadian 

 warbler (JVilsonia canadensis) shot at 7.30 a.m. registered 106.7° 

 and another taken at 9.45 a. m. gave a temperature of 107.6°. Females 

 of the same species taken at 7.30 and 9.00 on the same morning had 

 a bodily heat of 107.7° ^"^ 107.0° while a third bird of the latter 

 sex killed at 12.00 p. m. showed 108.3°. 



The daily increase in bodily temperature in our smaller birds may 

 be exemplified also by the following: On September 12, 1919, at 

 Plummers Island, Maryland, the writer spent the day in observing 

 small birds, many of which were in their southward migration. There 

 had been a heavy rain the previous evening, and later high wind had 

 come up with a considerable fall in temperature. The early morning 



