NORTHERN CRESTED FLYCATCHER 111 



racer {Coluher constrictor), the common watersnake {Natrix sipedon). 

 and one of the little green snakes. I saw in a nest a piece of snake- 

 skin that bore the unmistakable checkerboard pattern of the house- 

 snake {LampropeUis ti^iigulimi) ^ 



In my experience the snakeskin is usually found in small pieces, 

 more or less imbedded in the body of the nest or in the lining, but 

 in some cases it is conspicuously displayed on the rim or left hanging 

 in a long strip outside of the cavity. This has led to the oft-repeated 

 theory that it is used as a ''scarecrow" to frighten away predatory 

 mammals, birds, reptiles, or other enemies. Frank Bolles (1890) 

 was evidently convinced of the truth of this theory by the following 

 circumstantial evidence, of which he writes: 



In one instance, at Tainwoitli, New Hampshire, I found a nest witii one egg 

 in it but with no snake skin visible. I found it about 7 a. m. one beautiful 

 day in early July, 18S8. I touched the egg and handled the nest slightly. 

 Shortly before sunset I looked a second time into the hollow limb where the 

 nest was placed, and was much surprised, in fact somewhat startled, by what 

 I saw. Forming a complete circle about the egg, resting, in fact, like a wreath 

 upon the circumference of the nest cavity, was a piece of snake skin six or 

 seven inches long. The part which had encased the head of the snake was at 

 the front of the nest and was slightly raised. It may not be wise to found a 

 theory upon a single fact, but from the moment I saw tliat newly acquired 

 snake skin, placed as it was, I made up my mind that the Great Crested Fly- 

 catcher uses the skin to scare away intruders. 



He had a somewhat similar experience at the same nesting site the 

 following year, which still further convinced him. His experience 

 was suggestive, but not convincing. Charles L. Whittle (1927) has 

 published an interesting article on this subject, from which I quote 

 as follows: 



Since many species of birds have their young and eggs destroyed by snakee, 

 and since old birds at nesting time are greatly concerned when a snake is 

 seen near their nests, as I have often observed to be the case, it seems obvious 

 thar if such species, and presumably the Great-crest does not escape their 

 depredations, in seeking nesting material recognized snakes' sloughs as suf- 

 ficiently snake-like to act as scare-crows to other birds, or other animals, they 

 would themselves be too much alarmed on discovering the sloughs to use them 

 in nest building. Hence two corollaries appear to be justified: (1) that since 

 birds gather snakes' sloughs, they do not associate the flimsy, lifeless material 

 with their former wearers; and (-) that they themselves, not recognizing 

 that sloughs resemble snakes, do not employ them in nest building as scare- 

 crows, but in the same manner that birds occasionally use fragments of birch 

 bark, leaves, strings, newspaper, etc., as nesting material. 



The above argument seems convincing. Many other birds use 

 cast-off snakeskins as nesting material, some very extensively. I have 

 a nest of the eastern blue grosbeak in my collection tliat is almost 

 completely covered with several long pieces of such skin wound 

 about its exterior, in which case it mav have been used as decoration 



