10 BIRDS OF A MARYLAND FARM. 



can be understood only when one knows j List what crops of the region 

 are infested, and the identity and importance of the pest by which 

 each is chiefl}^ attacked; for onl}" then can one learn which birds select 

 the worst pests and destroy them in the largest proportion. 



With a view to ascertaining how far local conditions might modify 

 the details of general conclusions based on data from widely separated 

 regions, a study of the food habits of the birds on a particular farm 

 was undertaken. From Jul}^ 30, 1895, to July 24, 1902, visits were 

 made at frequent intervals and including every month of the year 

 except Januar}". To obtain an idea of the available food supply, the 

 insects, berries, and seeds found on the place were collected; the con- 

 dition of the crops and the insects infesting them were noted; detailed 

 observations of the birds' food habits were made in the field, and the 

 stomachs of 698 birds were collected and examined, 53 being those of 

 English sparrows and the remainder {'d4:D) those of native species. 

 One of the most serious disadvantages attending the work is that 

 from such a limited area one can not examine stomachs enough to get 

 a thorough knowledge of the food of each species, and is often com- 

 pelled to rely, for the general idea of the food, on conclusions drawn 

 from material collected elsewhere. Still, such information, supple- 

 mented b}^ the knowledge gained from local stomach collections and 

 field notes, has made it possible in most cases to determine whether a 

 given species is, on the whole, helpful or harmful to the farm in 

 question. 



TOPOGRAPHY OF BRYAN FARM. 



The farm chosen for this investigation is the Br^^an farm, at Mar- 

 shall Hall, Md. , on the south bank of the Potomac, 15 miles from 

 Washington, directh^ opposite Mount Vernon, Ya. (see PL I, frontis- 

 piece, fig. 2). The former owner of the farm, Mr. O. N. Br3^an, 

 was an enthusiastic collector of birds, plants, and Indian imple- 

 ments, and was known to many Washington scientists. On his death, 

 in 1892, his collections were given to the National Museum. The 

 farm passed to his nephew, Mr. George R. Bryan, to whom the author 

 is indebted for permission to conduct these investigations on the place, 

 and for cordial cooperation and uniform courtesy throughout their 

 course. The farm contains about 230 acres, of which 150 is cultivated 

 and most of the remaining 80 covered with timber, principal!}^ hard- 

 wood interspersed with pine. The arable land, forming as it does 

 nearW two-thirds of the farm, is all in one tract (see map, PI. II). 

 Its western limit is a straight line of fence separating it from the next 

 farm; its northern boundar}^, almost twice as long, is the nearly 

 straight shore of the Potomac River, which here flows from east to 

 west. A small bay, formed by an indentation of the river shore (PI. 

 Ill, fig. 1), a calamus swamp, 200 yards long (PI. YII, fig. 1), which 

 drains into the bay, and a tract of woodland (PL XVI, fig. 2) form 



