A Second Bird Survey 43 



census days was very similar, the temperature on the imme- 

 diately preceding days was widely different in the two' years, 

 being very high in 1913, and very low in 1917 ; so that in 1913 

 the winter residents had practically all disappeared, and the 

 number of purely migratory species present was also very 

 much less than in 1917. Thus, 1913 was an exceptionally 

 poor year for birds, in fact, considerably below normal ; and 

 1917 was fully as much above the ordinary. The difference 

 between 129 species observed in 1913, and 166 in 1917 well 

 illustrates this ; and the normal condition would probably be 

 about half-way between the two. Six species, however, — the 

 pied-billed grebe, great horned owl, bay-breasted warbler, 

 yellow-throated warbler, northern parula warbler and Bach- 

 man sparrow — seen in 1913 were not noted in 1917. Of 

 the six most numerous species, in point of individuals ob- 

 served, only three — the English sparrow, song sparrow, and 

 chimney swift — were identical in the two years, and their rel- 

 ative abundance was not the same. The abundance of the barn 

 swallow and tree swallow in 1913 was due to a large single 

 flock of swallows seen on the Anacostia River ; but no such 

 flock was present on the day of our observations in 1917. 

 Moreover, the list of birds least numerous was very different 

 in 1917, as only five out of nineteen are common to both lists. 

 These are the marsh hawk, king rail, woodcock, yellow palm 

 warbler, and blue grosbeak. The species of most general dis- 

 tribution, howeVer, show a much closer agreement, since eight 

 out of fourteen of the 1917 birds in this category are the same 

 as those in the 1913 list. 



The itinerary of each of the seventeen parties engaged in 

 this survey was as follows : 



1.— Great Falls, Virginia. Traveled by electric car from 

 Woodridge, D. C, to Fairview, Virginia, and return, 43 miles; 

 on foot, 18 miles, from Fairview, Virginia, to above Great 

 Falls on the Virginia side of the Potomac River. Character 

 of country traversed : woodland and thickets, 80 per cent ; 

 clearings and farm land, 17 per cent; swamp. 3 per cent. To- 

 tal distance traveled, 61 miles. Time in field, 5:00 a. m. to 



