NORTHERN CLIFF SWALLOW 481 



discovered that very few of the birds vrere in evidence although they 

 had come in their usual numbers earlier in the season. He says: 



An examination of tlie newly completed nests revealed dead birds in nearly 

 every nest. Large numbers were also found dead on the ground in the vicinity 

 of the buildings frequented by them. Twenty-two nests were examined on one 

 barn, about six miles northeast of this city, and thirty-seven dead birds were 

 found in the ne.sts. About two miles from this barn one hundred nests were 

 e:xamined on a large barn and dead birds were found, one or more in each 

 nest. Five or six miles northwest of the city a like condition of affairs was 

 reported. An investigation in a section of country six or eight miles north 

 and fifteen to twenty miles south of the city revealed a similar destruction 

 of Eave Swallows; the ground about the barn on one farm was reported "cov- 

 ered with dead birds." 



Mr. Kimball attributes this great mortality to the unusual weather 

 conditions prevailing in that section of the country. There was a week 

 of warm weather at the time the swallows arrived, followed by a 

 prolonged cold period. The warm weather probably brought the 

 birds north in advance of their usual time. Kimball estimates that 

 in the northern section of Illinois over 90 percent of the swallows 

 died. 



From the foregoing and other similar reports it is evident that 

 unseasonable cold weather may prove most disastrous to the cliff- 

 swallow population. In addition to the cold to which the swallows 

 are subjected and to which they are not adapted they also suffer pri- 

 vation from the lack at such times of their all essential food, flying 

 insects. 



Fall. — After the nesting season the adults and offspring of a colony 

 cling together for some time as a group. It is then that their presence 

 becomes conspicuous and attracts attention even from the casual ob- 

 server, who is impressed by their great numbers as they congregate 

 on telephone wires, buildings, or treetops. It is a common experience 

 when traveling along the New England highwaj^s late in July or 

 early in August to encounter many groups ranging in size from a 

 few dozen to 75 or 100 birds. Later the colony groups join with 

 others of the same and other species of swallows to roost in favoi'able 

 traditional places creating large concentrations numbering many 

 hundreds and even thousands of individuals. 



Jackson (1923) saw 300 cliff swallows at Bent's Camp, Mamie Lake, 

 Wis., from August 23 to 28, 1917. On August 29 there were 40, and 

 by August 31 there were only six left. Frances Schneider (1922) saw 

 1,000 cliff swallows congregated near a ranch reservoir near Artesia, 

 Calif., on July 2G, 1922. She noted another assemblage at the same 

 place numbering several hundreds on July 29. According to A. S. Allen 

 (1921) enormous numbers of cliff and other swallows assemble each 

 year in the Suisun Marshes, Calif., after the middle of July. Cooke 



