EASTERN BOAT-TAILED GRACKLE 373 



However, I often noted that immediately after the rattle had sounded 

 the wings were fluttered strongly. At times it appeared that the 

 mandibles produced it, for they were definitely moved, but with this 

 movement much less pronounced, the rattle sounded just as loud. 

 Still not completely satisfied in my mind, I have come to the provi- 

 sional conclusion that the sound is produced by a combination of the 

 rattle made in the throat and vibrations of the mandibles. It may 

 take slow-motion moving pictures to prove the source of this very 

 interesting noise, as it did in the long controversy over the drumming 

 of the grouse. 



Enemies. — One might assume that such a large and assertive 

 species as the boat-tail would be about as free from natural enemies 

 as any passerine bird. This may be generally true of the adults, but 

 not of the young. In addition to the abnormally large loss in nest- 

 lings already commented on, other agencies actively militate against 

 them. 



Audubon (1834) has written that the alligator (Alligator mississip- 

 piensis) is frequently attracted by the "cries of the young when they 

 are nearly fledged" and that, on hearing such notes, "well knowing 

 the excellence of these birds as articles of food, swims gently toward 

 the nest and suddenly thrashing the reeds with his tail, jerks out the 

 poor nestlings and immediately devours them," but predation from 

 this cause today is rare; at least I have never observed or heard of it. 



Parasites cause some mortality among the young. Audubon (1834) 

 stated that "My friend Dr. Samuel Wilson of Charleston, attempted 

 to raise some from the nest * * * and for some weeks fed them on 

 fresh meat but they became so infested with insects that not with- 

 standing all his care they died." That similar circumstances are 

 often present in the nest is well known. T. G. Pearson and the Brim- 

 leys (1942) say: "This is one of the species whose nests at times un- 

 fortunately are infested with parasites which, if they do not bring 

 death to the young * * * certainly add nothing to the comfort of 

 the household." 



Man, too must be listed among the enemies of the boat-tail, because 

 of the bird's tendency to despoil grain crops. Numbers are shot in 

 various localities, and in past years it must have been also the prac- 

 tice to use the young as food; Audubon (1834) quotes the Rev. John 

 Bachman as saying that grackles "are excellent eating whilst squabs." 



Field marks. — It is hardly possible to confuse the eastern boat- 

 tailed grackle with any other grackle except its larger relative, the 

 type species, Cassidix mexicanus mexicanus. The completely dark 

 plumage and huge, keeled tail and the fact that it seldom strays far 

 from a maritime habitat will always distinguish it. The female is 

 very much smaller than the male, of a uniform dark brown above, 



