Alternative Energy Draft EA - NASA Visitor Center at Wallops Flight ...

Affected Environment
To estimate how many birds were likely killed at the existing towers, the numbers of carcasses
found were multiplied by a factor of four. This factor includes a general searcher efficiency rate
of 50 percent and a carcass removal rate of 50 percent. The factor is calculated by multiplying
0.5 by 0.5 for a combined rate of 0.25, the factor of four used to calculate fatality rate. Studies of
bird carcasses at communication towers indicate that the factor of four is likely to reflect
searcher efficiency and carcass removal at a wide variety of habitats beneath communication
towers (Gehring et al., 2009).
Findings
The following is a summary of the data collected during the avian surveys described above;
detailed results are presented in the Avian Study Final Report (Appendix A). Although the
surveys officially started on October 1, 2008, some data collected prior to this date are included
in the report, particularly diurnal point count observations that began on September 12, 2008,
and one migration survey on September 22, 2008. Fatality searches began on October 3, 2008,
and ended on October 2, 2009.
Avian Field Observations
Species observed during the 79 surveys include almost 100 species of birds typical of the
avifauna community expected to occur at Wallops Island (Table 12). With the exception of snow
goose, which was 72.4 percent of the total number of observations, almost 30 percent of the bird
community observed was comprised of native species typically found in Virginia’s coastal
habitats (e.g., Tree Swallow, Canada Goose, Red-winged Blackbird and Great Egret, in order of
frequency of occurrence) as well as a common non-native species (European Starling) that
frequently occur in disturbed/urbanized habitats.
Table 12: Species Abundance Summary October 2008–October 2009
Percent of Total With Percent of Total Without
Number 20,000 Snow Geese 20,000 Snow Geese
Species
Observed Recorded on Single Day Recorded on Single Day
Snow Goose 23,321 72.4 27.2
Tree Swallow 1,569 4.8 12.8
European Starling 708 2.2 5.8
Canada Goose 501 1.6 4.1
Red-winged Blackbird 500 1.6 4.1
Great Egret 495 1.5 4.0
All other species 5,132 15.9 42
Total 32,226 100 100
A flock of 20,000 Snow Geese was observed on the far western side of the marsh adjacent to the
observation point on one day in November 2008. Table 13 shows the percentage of the total
number of birds observed excluding the 20,000-member flock of Snow Geese.
Waterfowl were the dominant class of birds observed (76.8 percent of all observations) (Table
13). Passerines, blackbirds, waders, gulls and terns, raptors, shorebirds and others were much
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