362 U. S. NATIONAL MUSEUM BULLETIN 211 



At times the boat-tail bedevils species much larger than itself, 

 setting upon them and driving them off with vituperative and vocif- 

 erous energy. Audubon relates that he has watched "seven or eight 

 of them teasing a Fish Hawk for nearly an hour, before they gave up 

 the enterprise." It is not unusual to see them converge on turkey 

 and black vultures (Cathartes aura septentrionalis) and (Coragyps 

 atratus), these slow-moving unfortunates having no protection from 

 their nimble and persistent tormentors but flight. 



The boat-tail often feeds in close proximity to cattle, both in barn- 

 yards and on the open range, principally to secure the insects dis- 

 turbed by the animals' feet. Whether they actually take ticks from 

 the hides of cattle I am not sure, but I have, on many occasions, 

 seen them alight on the backs of cows. The Florida crow (Corvus 

 brachyrhynchos pascuus) definitely secures ticks in this manner and 

 is highly regarded in the cattle sections of that State as an aid in con- 

 trolling the screwworm. About Lake Okeechobee the cattle are fond 

 of entering the drainage canals, which are choked with water-hyacinth 

 (Eichhornia crassipes); from knee to shoulder depth, there, standing 

 in water they feed to repletion on this plant. At such times one can 

 see numbers of boat-tails about them, walking about on the floating 

 vegetation or actually perched on the animals' backs, snapping up 

 insects stirred up by their movements. 



Albinism occurs in this form as in the eastern race (see p. 371). 

 During February and March 1946, such an individual was observed on 

 six occasions on the north shore of Lake Okeechobee, Fla., always 

 within one hundred yards of the same spot. 



Voice. — The voice of this bird is similar to that of the eastern 

 race (see p. 371), including the characteristic rolling or rattling sound, 

 as may be seen from the following accounts. A. H. Howell (1932) 

 describes a bird he heard near Jupiter Inlet, Fla., as ending its 

 song "by a peculiar, guttural, clattering sound that seemed to be of 

 vocal origin, though accompanied by a fluttering of the wings." 

 E. S. Dingle (1932) remarks: "Besides the great number of sounds 

 that issue from its throat, one frequently hears a curious rolling noise, 

 made by the wings when the bird is perching, but occasionally during 

 flight." F. M. Chapman (1912) has likened this "singular rolling 

 call" to the sound produced by a coot in pattering over the water. 



That it is instrumental, indeed, is the first impression experienced 

 by all who have written about it, but to those who have followed 

 it subsequently it is plain that this is not the case. The two most 

 concise and detailed accounts of recent years are those of Francis 

 Harper (1920) and C. W. Townsend (1927). 



Harper says that while studying this grackle's voice in Florida he — 



Began to pay close attention * * * particularly to that part of it which 

 Chapman describes as a "singular rolling call, which bears a close resemblance 



