1232 U.S. NATIONAL MUSEUM BULLETIN 237 part 2 



2.45 young cowbirds per year for the 100-acre tract over the 11-year 

 period does not seem overly serious, nevertheless cowbird interference 

 retarded the field sparrow nesting cycle and production of young 

 considerably. As the cowbirds usually laid no eggs after mid-July, 

 the sparrows did not have this trouble to contend with during their 

 last nesting. 



H. S. Peters (1936) lists 13 different ectoparasites found on the field 

 sparrow, including four species of biting lice (Mallophaga) , two of 

 flies, four of mites, and three of ticks. R. O. Malcomson (1960) adds 

 another Mallophaga to this list, and C. Herman (1944) reports finding 

 the blood protozoan, Plasmodium in the species twice. 



Unseasonable spells of inclement weather such as extreme cold with 

 snow or sleet, extreme heat, and heavy wind and rain all take their 

 toll of this species. M. P. Crooks (MS.) reports all the eggs and young 

 he was studying were lost during a late spring snowstorm. In early 

 nests before the vegetation has leafed out enough to provide shade, 

 the hot sun may cause the young to leave the nest prematurely. I 

 have found a number of such young dead within a short distance of 

 the nest, killed either by the heat or by small red ants which had 

 already partly devoured them. These ants were found to kill healthy 

 small young, left unprotected in the nest by adidts, in an hour. 

 Heavy downpours with high winds often "WTecked nests in bushes or 

 dumped eggs or young out onto the ground. 



I have found many field sparrows killed by cars on the roads. The 

 most recent modern perils for these and other night migrants are the 

 ceilometer beams at airports and tall television towers. A. R. Laskey 

 (1957, 1960) reports at least 23 field sparrows killed by flying into the 

 tower at Nashville, Tenn. H. L. Stoddard (1962) reports 24 field 

 sparrows among the some 15,200 individual birds of 150 species killed 

 at a television tower 20 miles north of Tallahassee, Fla., between 

 1955 and 1961. 



Fall and winter. — After nesting acti\dties in Michigan cease in late 

 summer adidts and young start forming flocks that remain on their 

 favorite brushy fields throughout most of September. Hundreds may 

 be found together in especially good feeding areas. They roost at night 

 in small trees or bushes still heavily covered with leaves. Banding 

 operations show the birds start moving southward in mid-September, 

 and the population changes continuaUy as the migrants keep coming 

 through until the 2nd week of October. Though individuals occasion- 

 ally linger into November, most have left by mid-October. 



In NashviUe, Tenn., where the species both breeds and winters, 

 Mrs. Laskey (1934b) found, through banding, that the population 

 changed regidarly. Though she captured immature birds she con- 



