168 



AMERICAN FORESTRY 



In summer, Bonaparte's weasel is of a dark brown 

 color above, the under parts and upper lip being of a 

 yellowish white. One that the writer saw caught in a 

 box trap was in winter pelage, and one of the most 

 beautiful little creatures imaginable more attractive than 

 beautiful perhaps, in the sense we would use the latter 

 word when describing a mammal with a pelage exhibiting 

 some bright color. 



A considerable amount of discussion has appeared in 

 various works devoted to the life histories of mammals in 

 regard to the 

 mode of change 

 of the color of 

 the hair of the 

 coats of those 

 animals that 

 exhibit summer 

 coloration, and 

 then, with more 

 or less sudden- 

 ness, don one 

 of white, or 

 nearly white, 

 for the winter 

 season. Wea- 

 sels that do 

 this have come 

 in for their full 

 share of the 

 various opin- 

 ions held by 

 z o ol og i sts. 

 Some believe 

 that one of 

 these animals, 

 in changing to 

 the white pel- 

 age of winter, 

 sheds the fur, 

 the coat of 

 white being en- 

 tirely new. 

 Others have 

 contended that 

 owing to a cer- 

 tain falling of 

 temperature at 

 the beginning 

 of winter, the coat of the weasel simply turns white, the 

 hair not being shed at all; while still others affirm that 

 it is due in part to this, and in part to the old coat being, 

 to some extent, replaced by the winter one or vice versa. 

 In other words, there are in general two ways in which 

 the change may take place. Those who have studied the 

 question most closely contend that the change may or may 

 not be coincident with the shedding of the coat. Such an 

 opinion is based upon the fact that, in examining a large 

 series of specimens, examples have been met with where- 



SOME WEASELS ARE TRULY BEAUTIFUL IN THEIR WINTER COATS DOCUMENTARY EVI- 

 DENCE HEREWITH. (Photograph by the author of the Long-tailed Weasel, No. 102089 in the United 

 States National Museum. Somewhat reduced.) 



Fig. 9. 



in the white hairs have been found to be tipped with 

 brown, with a dark brown stripe of new hair down the 

 back, being a part of the incoming spring coat. Autumnal 

 specimens show the former condition and vernal ones 

 the latter. Temperature markedly affects it, and to a 

 large extent is the controlling agent. This is supported 

 by the fact that the northern species only assume the 

 complete white coat in winter, while the extreme southern 

 forms never exhibit any such change. Species ranging 

 in the intermediate regions are often piebald, and re- 

 main so until 

 the shed gives 

 them a new 

 coat of the 

 summer season 

 that is, the 

 bi-colored one. 

 Under ordi- 

 nary circum- 

 stances, the 

 change from 

 the white coat 

 to the summer 

 pelage takes 

 about three 

 weeks ; but this 

 may be retard- 

 ed or hastened 

 by the condi- 

 tions of the 

 temperature in 

 the early 

 spring months. 

 The change 

 is of marked 

 service to the 

 animal. The 

 white coat 

 largely protects 

 the weasel 

 against its ene- 

 mies, while it 

 serves to ren- 

 der it incon- 

 spicuous and 

 difficult to be 

 seen by its 

 prey. The col- 

 ors also equal- 

 ize the temperature of the animal's body. A great authority 

 and close observer of the phenomenon states that "it is 

 too well known to require more than an allusion that, 

 although the darker colors absorb heat to a greater degree 

 than lighter ones so that dark-colored clothing is much 

 warmer than light-colored when the wearer is exposed to 

 the sun's rays the radiation of heat is also never greater 

 from dark than from light-colored surfaces, and conse- 

 quently the animal heat from within is more completely 

 retained by a white than by a dark covering. Therefore, 



On account of its long tail, science has named this species Ptttorius longicauda, and it has a range 

 over the great Plains from Kansas northward. 



