NO. 12 BODY TEMPERATURE OF BIRDS WETMORE I7 



degree of heat equivalent to that of the tissues inclosing it. In this 

 way a distinct lowering of internal heat may be occasioned. On 

 Sept. 12, 1919, while watching two yellow-throated viroes {Lanivireo 

 ■flavirons) that were feeding in company I saw one after much effort 

 swallow a very large caterpillar. Both of these birds were collected 

 and were found to l)e immature females. The bird that had eaten the 

 caterpillar five minutes before it was killed registered a body tem- 

 perature of 107.2°, while the other gave a reading of ioS.i°. This 

 difference of .9° was attributed to heat absorbed by the large mass 

 of recently ingested food. This may be considered a normal variation. 



In small birds bathing may also occasion a slight decrease in body 

 temperature where the plumage becomes thoroughly wet. The heat 

 taken up during evaporation incident to drying the feathers may 

 occasion an appreciable drop in body heat. As an example of this, 

 a verdin {Auriparus flaviceps) that had just bathed, taken June 16, 

 1919, near Arlington, Arizona, gave a temperature of only 106.0°, 

 while others of this species ranged from 106.5° to 107.6°. Variation 

 from this cause is slight, however, and would not be appreciable save 

 in species of very small size. 



Many persons with whom the writer has discussed the question of 

 the taking and recording of the body temperatures of birds have 

 expressed the belief that the shock produced in, the bird when it is 

 shot is sufficient to increase the bodily temperature to a marked degree. 

 Such statements have come in particular from physicians and others 

 of similar training. Experiment and observation have shown, how- 

 ever, that this is not true. On various occasions by accident or inten- 

 tion birds have been killed in such a way that they were instantly 

 riddled by shot, so that all functions of the body, nervous as well as 

 circulatory must have ceased instantly when the bird was struck, 

 and this on occasions when the individual in question had no reason 

 to suspect danger. Temperatures of such specimens show no varia- 

 tion from those of birds taken in a more normal way. As a matter 

 of fact it has transpired that the shock of wound in birds serves rapidly 

 to reduce their body heat after a period of from thirty to sixty 

 seconds. Thus a wing-tipped bird, with an injury that is compara- 

 tively slight, will be found usually to have a temperature below 

 normal after a period of two minutes has elapsed from the time that 

 it was injured. With more serious injuries the fall in body heat may 

 be so great that a record made on a living bird four or five minutes 

 after it was shot is so low that it must often be considered as abnormal. 

 As an example of this I may cite the case of a cinnamon teal (Ouer- 

 quedula cyanoptcra) that was struck in such a way that the sight of 



