
and a second, 0.8 mile long, in the 0.8 area. These included transects 
through both tall and short grass habitats. Counting trips were made on 
each of the two areas in the early morning and late afternoon of the two 
days preceding spraying. Following spraying, trips were again taken in the 
late afternoons between the fourth and eighth days. it was reasoned that 
the greatest effect of reduced insect food supplies might be evident during 
this period. 
The counting procedure involved walking the routes and noting 
the individuals flushed, seen, or heard. The effective recording range on 
either side of the strip was considered to be about 75 feet in the case of 
small birds and 300 feet for larger or more conspicuous ones. Swallows 
were so numerous that only those flying in front of the observer within 
a distance of 150 feet were counted. The strip count method did not prove 
to be practicable for rails. A few were heard and seen each trip and only 
the higher of the sight or sound records was listed. In all cases, strip 
counts were limited to birds regarded as residents or regular visitors to 
the marsh. 
Before spraying, the number of resident birds per trip on the 
1.6 area averaged 27~3/ compared with 26~3/) after spraying, a decrease 
of 4%. Comparable figures for resident birds on the 0.8 area were 31 and 
3u-1/4, an increase of 10%. It appears, therefore, that DDT application 
had no significant effect on the resident bird population on these two 
areas during an eight-day period following spraying. 
Visitant birds feeding within the 1.6 area averaged 5l)-3/l per 
trip before the spray and 25-1/2 afterwards, a decrease of 53%. However, 
the swallows accounted for most (93%) of this decrease since their numbers 
diminished 55% while other species decreased 36%. The decline in the 
number of laughing gulls following spraying was responsible for the greater 
part of the remainder of decrease. In the 0.8 area, also, the number of 
visitants after spraying fell off sharply, declining from 30~-1/l to 17, 
or 4%. As in the 1.6 area swallows accounted for the greater part of 
this reduction. 
