Methods: 
4k „ 
From a 1988 aerial photograph a map was made showing the forests on 
the S.E.R.C. property. A 0.4 km squared grid was superimposed on the existing 
1 ha grid system. All except 9 cells censused had > 50 percent forest. 
Selected cells were scouted and marked in the center with yellow flags 
before censusing. Data on vegetation characteristics were recorded at each_ 
site. This included percent forest cover, forest age, plant species diversity 
and density and amount of edge. See appendix A (data sheet) and appendix B 
(document file) for more complete detail on vegetation and other site variables. 
At each site two kinds of counts were used: 1) 10 minute standard or passive 
counts, meaning recording data by quietly watching and listening, followed by, 
2) 10 minute playback counts during which the songs of woodthrush, red eyed 
vireo, white eyed vireo, ovenbird and hooded warbler were played. Each song 
was played for 45 seconds followed by an approximate one minute listening period 
The recordings were played on a small Realistic 4 AA battery powered 
cassette/recorder along with a portable Realistic 4 C battery powered dual 
speaker/amplifier system. The playback was played at a constant volume 
and the speakers rotated during play. 
The recordings of the woodthrush and red eyed vireo were made in 
north-western Pa, the white eyed vireo somewhere in Md, and the ovenbird 
and hooded warbler were recorded at S.E.R.C.. All recording were made on a 
Urer 4000 Reput Monitor tape recorder. 
Durning both counts I focused on the 5 species recorded on the 
playback. All other species heard or seen were also recorded although not 
their exact numbers. At each site (except for the subset, I will discribe 
below) a 10 minute standard count was followed by a playback count. On the 
data sheets an open circle symbolized that a bird was detected in the first 0 
to 5 minutes of the count. A half moon indicated detection between the 5 
to 10 minute portion of the count. Finally, a solid circle indicates that 
the bird was detected durning the 10 to 20 minute portion of the count 
(the playback portion). 
In situations where it was uncertain if there was a additional bird 
it was assumed that there was. There were 21 of these cases for woodthrush, 
32 for red eyed vireo, 0 for white eyed vireo, 23 for ovenbird and 0 for hooded 
warbler. These are marked on the computer sheet by a small square in the upper 
right hand corner of the box in spaces 14 to 47. 
A total of 104 sites were censused. The first 23 censused were 
repeated on subsequent days using 10 minute playback counts only. In July 
after the 104 censuses were all completed, 18 of the 23 recounted sites were 
again censused twice; first with 20 minute counts, and secons with 10 minute 
playback counts on subsequent days. The total number of counts conducted was 
163 . 
Discussion: 
We have shown that over the entire season the playback counts do not 
considerally add to the number of birds detected. This can be seen in the 
species vs date graphs which do not show an increase between the 'T' 
(standard + playback counts) and 'P' (standard counts only) as the season 
progressed. We would expect to see an increase if normal bird activity 
dropped but could be enhanced with the playback. Likewise, after parametric 
2 way analysis of variance stastical test the recensused sites did 
not show a difference in the playback only and standard only means both 
early and late in the census. 
A census for ovenbirds should end before July 1 since it was found 
that their numbers significantly droped by mid July. Woodthrush seems to 
show some decline with the progressing season. The other species did not 
seem to decline much. 
The most common of the 5 species is the red eyed vireo. Next most 
common was woodthrush followed by ovenbird. White eyed vireo and hooded 
warbler occured almost equally (see table 1). It is not clear which is more 
common since they have different habitat requirements. 
A test of standard 20 minute counts compared with 20 minute standard 
and playback counts should be conducted to test whether the additional 
individuals detected durning the playback was due to the tape or simply 
the additional listening time. 
