II. The Final Report on Bat and Avian Studies
(Supplementary Environmental Impact Statement)
Within the Supplementary Environmental Impact Statement
(SEIS) is the Draft Final Report on Bat and Avian Studies for the Proposed St.
Lawrence Windpower Project. It
should be noted that the Draft Final Report was chosen for our discussion
because the Final Environmental Impact Study does not include a comprehensive
report concerning bat and avian species as a whole. This study (again conducted by West Inc and prepared for the
St. Lawrence Windpower, LLC) was broken up into the following subtopics: Nocturnal Marine Radar Surveys; Raptor
Migration Surveys; Breeding Bird Surveys; Nocturnal AnaBat Surveys; and
Waterfowl and Winter Raptor Surveys.
Our discussion of this study will follow the order that is used in the
SEIS.
These preconstruction studies used a variety of methods to
record data including fixed point and point count surveys for avian species,
and the AnaBat sampling method for bats.
Studies were conducted during spring and fall migration periods, as well
as throughout the year. Each study
has a unique set of methods that will be elaborated upon within each
subsection.
A. Nocturnal Marine Radar Surveys
The goal of the Nocturnal Marine Radar Survey was to assess
the usage of the proposed wind farm site as a migratory path. Furthermore, this data was compared to
other sites in the surrounding area to evaluate whether or not the Cape Vincent
area is a preferred migratory path.
If migratory usage was found to exceed that of other sites, it could be argued
that the St. Lawrence Wind Farm would be an obstacle for migrating birds.
A single X-band marine radar unit was used for the survey,
as it has been successfully monitored nocturnal migration in the past. Radar was used so that flight
direction, passage rates, and flight altitude could be analyzed. The study was conducted in both the
fall and spring migration periods.
The fall migration period is defined as the 15th of August to
the 15th of October. A
full explanation of the methods used in this survey is provided on pages 7 and
8 of the Draft Final Report regarding Avian and Bat Studies for the Proposed
St. Lawrence Windpower Project.
1. Flight
Direction
From the survey, a trend was found
that showed birds migrating in a Southwestern direction for the Fall and in a
Northeastern direction for the Spring.
This could be attributed to that fact that most birds tend to follow the
shoreline of Lake Ontario rather than fly across it in a linear fashion.
2. Passage
Rates
Assessing the passage rates of bird
species provides an idea on how many individuals are using the area at once,
and at what frequency. Analyzing
such data allows researchers to assess how often an area experiences bird
passage. To avoid errors in data,
the survey team used alternative frequencies to rule out air-clutter and
rain-clutter variables from the passage rates. This was done to avoid inflating the results. The survey on passage rates was
conducted in both a horizontal and vertical manner, so as to decrease the
margin of error. The results are
expressed as the mean amount of targets per kilometer per hour
(targets/km/hour). The +/- symbol
denotes the standard deviation, which explains that the actual results could
deviate a certain amount from the mean.
The results are summarized below:
Fall Horizontal survey: 345.8 +/- 13.3 targets/km/hour
Fall Vertical survey: 346.2 +/- 17.2 targets/km/hour
Spring Horizontal survey: 166.2 +/- 8.8 targets/km/hour
Spring Vertical survey: 191 +/- 9.4
targets/km/hour
3. Flight
Altitude
The flight altitude survey looked
at whether or not the birds that used the Cape Vincent area would fly in
risk-zone of the wind turbines.
The risk-zone is defined as below 125 meters, which is roughly the
height modern wind turbines. This
is the area where collisions are likely to occur. Again, radar was used to collect this data and is separated
between the fall and spring migration surveys.
For the fall, the mean flight
altitude was 490.4 +/- 1.7 m, with a sample population of
30,749 individuals. The highest
percentage of individuals had flight altitudes between 201 – 300 m. Of the total sampling population, 7.7%
of all individuals sampled had flight altitudes below 125 m, which put them
within the risk zone. However, it
was found that the middle 50% of the sampling distribution had flight altitudes
greater than 125 m.
For the spring, the mean flight
altitude was 441.3 +/- 2.5 m, with a sample population of
16,151 individuals. The highest
percentage of individuals had flight altitudes between 101 – 200 m. Furthermore, 14.0% of the total
sampling population flew at altitudes that were lower than 125 m. This coincides with the middle 50% of
the sampling distribution overlapping with the risk-zone. This survey suggests that spring
migrations are twice as likely to move through the proposed development area.
The results of the Nocturnal Marine Radar Survey are argued
to be similar to other New York State sites, as well as to other sites across
the Eastern United States.
The migration directions are slightly more angled towards Southwest in
the Fall and Northeast in the Spring, however this could be attributed to the
presence of Lake Ontario. Passage
rates are similar to those of other New York States. Furthermore, the collision risk is also similar to other
sites in New York State. The
researchers suggest placing the turbines 1.5 kilometers or greater from the
shoreline to minimize risk.
B. Raptor Migration Surveys
The goal of the Raptor Migration Survey was to use point
count surveys to assess the use of the Cape Vincent area by migrating raptor
species in addition to other large bird species. Within circular plots, point counts were conducted with
surveyors scanning their surrounding area for raptor and/or other large bird
species. Three survey points were
chosen within the proposed development area for their 360-degree visibility
advantages. Surveys were conducted
for the spring 2006, fall 2006 and spring 2007 migration periods. Methods for the survey were borrowed
from the Hawk Migration Association of North America (HMANA), and are fully
explained within the Draft Final Report.
A survey was conducted at each point for the spring 2006
migration season, which recorded 1,581 individuals in the end. Out of the total, 91 of these
individuals were raptors, spread across 9 species. Turkey vulture was the most commonly seen raptor species (51
indiv.), next of which was the red-tailed hawk (8 indiv.).
Unlike the spring season, a survey was conducted 10 times at
each point for the fall 2006 season.
These surveys identified 8,521 individuals, of which 228 individuals
were raptors, spread across 9 species.
Northern harrier was the most common species (87 indiv.). Again, turkey vulture and red-tailed
hawk were common.
For spring 2007, a survey was conducted at each point 7
times. The total amount of
identified individuals was 2666, of which 232 were raptors, spread across 8
species. Like 2006, the turkey
vulture was the most commonly seen species (105 indiv.), and again rough-legged
hawk came second (38 indiv.), with red-tailed hawk coming in third (36
indiv.).
Totals for the three surveys were 12,768 individuals, with
611 raptors identified across 13 different species.
Out of all the surveys, Canadian Goose and unidentified gull
species were the most common birds observed. However, other species of raptors that were identified
included the following: broad-winged hawk, Cooper’s hawk, osprey, merlin, and
bald eagle.
The results of the surveys show that the Cooper’s hawk is at
considerable risk due to the fact that all individuals observed were within the
risk-zone. The sharp-shinned
hawk shows the next highest risk, as 58.33% of all individuals identified were
in the risk-zone. However, these
species, along with all other hawk species observed, exhibit low-risk factors
due to the fact that their migratory usage of the Cape Vincent area in spring
is low compared to other NYS areas.
Overall, hawk use in the area is considerably lower than most other
areas studied. In the contrary,
turkey vultures can be expected to experience the highest risk due to their
high usage of the area, even though these risks may be relatively low.
C. Breeding Bird Surveys
The intent of the Breeding Bird Survey was to assess the
usage of the area by resident breeding birds. Essentially, the survey sought to find out how many birds
that live in the Cape Vincent area use the proposed area as breeding
grounds. Twenty survey points were
selected and spread out to cover as much as the proposed development area and
available habitats as possible.
Survey methods were adopted from the 2001 United States Geological
Survey Breeding Bird Survey.
Although the emphasis was to observe within 400 m of the survey points,
all birds were recorded. Two
surveys were conducted at each of the survey points between June and July of
2006.
A total of 1080 individuals were recorded during the survey
period, which comprised 59 different species. Of these totals, the following species were the most common:
European starling; red-winged blackbird, and bobolink. It is no surprise that such species
were recorded, as they are most commonly found within agricultural and
grassland habitats, as well as the edge habitats surrounding them. Cape Vincent has all three habitats
available.
The species of greatest concern that were identified are
listed below:
1. Northern
harrier (NYS Threatened species)
2. Horned lark and the grasshopper
sparrow (NYS Species of concern)
3. Bobolink and wood thrush
(included in the USFWS 2002 Birds of Conservation Concern list)
D. Nocturnal AnaBat Surveys
Much like the Marine Radar Surveys, the AnaBat surveys
utilize radar to survey the usage rates of bats within the spring and fall
migrations, as well as during the summer breeding season. The spring sampling period was
conducted between April 13th – May 29th, the fall
sampling between August 13th – October 16th, and the
summer sampling occurred between June 28th – August 8th. Both stationary and mobile AnaBat
survey units were employed, so as to cover the most amount of area as
possible. AnaBat works by
receiving the frequency of the echo-location used by bats, matches it to a
specific species’ frequency, and then records it.
Of all the bat calls that were recorded, 93% of them
occurred during August 15th and August 21st, suggesting
that the most bat activity in the area occurs during the summer breeding
period. After qualitative
screening processes, only 132 of 464 calls recorded in the summer period
contained enough data to positively identify the bat species in the area. The four bat species identified and the
number of recorded calls are listed below:
Eastern red bat: 22
Little brown bat: 50
Northern myotis: 44
Indiana bat: 16
E. Waterfowl and Winter Raptor Surveys
The purpose behind the Waterfowl and Winter Raptor Surveys
was to assess the use of the proposed development area by wintering and migrant
waterfowl and raptor species. This
was largely in response to the initial concern expressed for such species when
the project was first proposed.
Driving transects conducted on all the roads within the development area
provided a survey of nearly the entire area, with the assistance of nine point
surveys that were conducted at fixed points. Waterfowl, raptors, and other waterbirds were recorded for
the survey. The surveys were
conducted between November 5th, 2006 and March 1st, 2007
with a combined total of more than 40 hours of survey time.
Close to 800 individuals were found during both the driving
transects, as well as for the fixed point surveys. Each survey identified nearly 150 different species. Overall, the study found that the
Canadian goose is by far the most common wintering waterfowl bird in the
area. This is largely because
Canadian goose is reaching points of overpopulation. Any effects to the wintering population of Canadian goose
are considered not to be significant to the overall population. In addition, the red-tailed hawk and
the rough-legged hawk were the most common raptor species.
References
Kerns, J., Young, D., Nations, C. et al. (2007, August). Avian
and Bat Studies For
Proposed St. Lawrence Windpower Project, Jefferson County, New York.
Retrieved from: http://stlawrencewind.com/SEIS/SectionsPDF/Appendices/AppendixE_1_BBStLawrenceWind2006FinalReport.pdf
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