1222 U.S. NATIONAL MUSEUM BULLETIN 23 7 paex 2 



immediately returned to his own territory. She still maintained her 

 position, and a second neighboring male came and copulated with her. 

 Her rightful mate then came flying swiftly back, and drove the second 

 intruder away. He then returned to his mate, and both fed together 

 as usual on the ground, softly chipping to each other. 



M. P. Crooks (MS.) states: ''Copulation usually occurred while the 

 female was perched on a low limb or a small shrub, though occasionally 

 on the ground. All but three of the many copulations witnessed took 

 place during the nest-building period and between 6:45 and 9:30 a.m. 

 I saw one pair copulate April 27, 11 da3^s before the female began 

 nest building and 15 days before she laid her first egg. Two other acts 

 took place July 31, after the females had completed laying all the eggs 

 for the season. 



"One pair was seen copulating at 7:15 a.m. on the 3rd and last day of 

 nest building. They had been feeding together for the previous 10 

 minutes. After the act the female sat quitely for about a minute, then 

 resumed feeding. The male flew a short distance away and preened, 

 chipping very softly meanwhile. At 7:47 they copulated again, and 

 once more at 8:03 a.m. After this both continued to feed and preen, 

 and the female did not go back to nest building the rest of the 

 morning." 



Nesting. — During normal seasons the field sparrows start nesting in 

 northern United States and Ontario before the trees and shrubs start 

 to leaf out. Consequently the first nest is almost invariably built in a 

 thick clump of weeds or under a grass tuft on or very near the ground. 

 On my Michigan study areas most of the first nests were built beneath 

 the drooping leaves of fall witch-grass, Leptoloma cognata that grew on 

 the sides and tops of the hills. As the season advanced later nests 

 were built off the ground in small thick shrubs. 



From 1938 through 1948 I measured and recorded the heights of 

 661 nests. Of 173 May nests, 135 were on the ground, the highest was 

 31 centimeters above it, the average height was 7.46 centimeters. 

 Of 239 June nests, 36 were on the ground, the highest was 84 centi- 

 meters, the average was 21.35 centimeters. None of the 240 July nests 

 was on the ground; they ranged from 8 to 97 centimeters high and 

 averaged 30.64 centmeters. The nine nests built in August ranged 

 from 15 to 58 centimeters high and average 30.8 centimeters. 



The nests were built in the follo^\'ing vegetation: 124 in New Jersey 

 tea bushes, 122 in or under fall witch grass, 80 in blackberry bushes, 

 61 in small hawthorns, 45 in cinquefoil, 42 in small oaks, 30 in golden- 

 rod clumps, 19 in small hickories, 13 in hazelnut bushes, 11 in sweet 

 clover clumps, 10 in black raspberries, 10 in grape vines, 10 in grass 

 clumps other than Leptoloma, 9 in dwarf sumac, and less than 4 each 



