EASTERN FIELD SPARROW 1219 



giving very thick cover, but they are also scattered over the hillsides so there are 

 no large areas of open land. The trees generally grow taller in the valleys than 

 on the hillsides. 



Another area is a pasture of about 25 acres used by 14 cows. The lower part 

 is in woodland, and only the upper 15 acres were used by field sparrows. The 

 type of cover these birds used was sparse with only occasionally hawthorn shrubs 

 that survived the grazing and trampling of the cows. * * * The predominant 

 cover is Kentucky bluegrass. Hawthorn shrubs are scattered thinly over the 

 area, while the overstory is mainly English walnut, Juglans repustris, cottonwood, 

 Populus deltoides, and green ash, Fraxinus lanceolata. 



Spring. — From their wintering grounds in the southern United 

 States the field sparrows closely follow the warming spring northward. 



They migrate mostly at night, traveling in small flocks, often with 

 other sparrows. They do not first appear on their northern breeding 

 grounds in flocks, however, but arrive a few individuals at a time. 

 Suddenly one nice warm morning, an area where hitherto no birds 

 were in evidence is found to have three or four singing males scattered 

 widely over several hundred acres of brush-grown fields. If the weather 

 turns cold, no new birds appear until the next warm spell brings ad- 

 ditional males. They continue to trickle in until soon territories are 

 established in most of the available habitat. When in a few weeks 

 the females begin to arrive, they come in more rapidly, but still 

 individually and not in flocks. 



The average date of arrival of the first males at Battle Creek was 

 March 31 over a 43-year period; the earhest date was Mar. 14, 1957, 

 and the latest was Apr. 15, 1924. The females generally arrive 3 

 weeks later, in late April. 



Territory. — Though not so belligerent about it as many other 

 species, the field sparrow is strongly territorial. Immediately on 

 arrival each male selects a territory which he proclaims and defends 

 against encroachment by other males. He flies from one tree or bush 

 to another on the area he wishes to claim and sings from four or five 

 favored spots, usually the tops of prominent shrubs or saplings. 

 From each of these he pours forth his plaintive Httle song, most 

 actively during the early morning hours. 



If a new male arrives and tries to settle adjacent to his territory, 

 the two birds begin to establish a definite boundary between their 

 domains. This may take several days of intermittent conflict. The 

 estabUshed male chases the new bird back and forth along the boundary 

 whenever he encroaches on it until one or the other tires and both stop 

 to rest. The new male sings a low song again and again; the estab- 

 Ushed male sings less frequently. The chase renews, and sometimes 

 the new male chases the established one. Seldom do the two come 

 into bodily contact, the pursued bird managing to keep just out of 

 reach, 2 to 5 feet ahead of the other. Occasionally, however, they 



646-737— 68— pt. 2 41 



