U. S. NATIONAL MUSEUM BULLETIN 211 



Columbus, Ohio. For 9 days, October 6 through 15, 1934, she deter- 

 mined with a Weston photometer the light values in the morning and 

 evening at the times the birds left and arrived at the roost. On seven 

 clear mornings their first flights left from 7 to 9 minutes before sunrise 

 at light values of 13 to 16 foot-candles (median 14). On one cloudy 

 morning they left 3 minutes before sunrise at a light value of 13.5 foot- 

 candle. The largest flocks left at light values of 20.5 to 29 foot- 

 candles. In the evening the first flocks were seen about half an hour 

 before sunset. Light values ranged from 114 to 40 foot-candles but 

 the height usually occurred between 65 and 52 foot-candles. The 

 flight ended just about sunest, from 1 minute before to 3 after. Mrs. 

 Nice determined that leaving and returning to the roost was closely 

 correlated with light, and that the grackles went to roost when the 

 light was about three times as bright as it was when they left it. 



E. H. Forbush (1907) gives a graphic account of bronzed grackles 

 on their fall migration flight which he observed at Concord, Mass., on 

 October 28, 1904, as follows: 



From my post of observation, on a hilltop, an army of birds could be seen 

 extending across the sky from one horizon to the other. As one of my companions 

 remarked, it was a great "rainbow of birds;" as they passed overhead, the line 

 appeared to be about three rods wide and about one hundred feet above the hill- 

 top. This column of birds appeared as perfect in form as a platoon. The in- 

 dividual birds were not flying in the direction in which the column extended, but 

 diagonally across it; and when one considers the difficulty of keeping a platoon of 

 men in line when marching shoulder to shoulder, the precision with which this 

 host of birds kept their line across the sky seems marvelous. As the line passed 

 overhead, it extended nearly east and west. The birds seemed to be flying in a 

 course considerably west of south, and thus the column was drifting southwest. 

 As the left of the line passed over Concord meadows, its end was seen in the dis- 

 tance, but the other end of this mighty army extended beyond the western horizon. 

 The flight was watched until it was out of sight, and then followed with a glass 

 until it disappeared in the distance. It never faltered, broke, or wavered, but 

 kept straight on into the gloom of night. The whole array presented no such 

 appearance as the unformed flocks ordinarily seen earlier in the season, but was of 

 finer formation than I have ever seen elsewhere, among either land birds or 

 waterfowl. It seemed to be a migration of all the Crow Blackbirds in the region, 

 and there appeared to be a few Rusty Blackbirds with them. After that date I 

 saw but one Crow Blackbird. It was impossible to estimate the number of birds 

 in this flight. My companions believed there were millions. 



Dr. Charles Blake of Lincoln, Mass., has written us concerning a 

 flock of 3,100 bronzed grackles he observed on their migratory flight, 

 October 30, 1942. The flock, which required 15 minutes to pass, was 

 about 300 feet wide but contained a fixed wave so that the flight was 

 undulated over a width of fully three-tenths of a mile. 



Recoveries of bronzed grackles banded by Charles B. Floyd (1926), 

 Mabel Gillespie (1930), and others, clearly indicate that the fall 

 migration is in a southwesterly direction along the Atlantic coast. 



