1.1
Section 6.2.5
of the approved EM&A Manual for the Project requires that potential work
disturbance to inter-tidal bird communities is monitored during the
construction phase. Appendix 1 shows the requirements and Event and Action Plan
for monitoring works.
2.1
Equipment used for monitoring
included a 20-60x spotting scope, 10x42 binoculars, and Hand-held GPS.
3.1
Monitoring was conducted at two
locations, Ngau Hom Shek (NHS) and Sheung Pak Nai (SPN). Monitoring at NHS was
adjacent to the works area, and provides a record of potential construction
phase disturbance. The SPN site is relatively distant from the works area, and
was used as a control site.
4.
Monitoring Methodology
4.1
Bird species and abundance
within a 100m quadrat of exposed
mudflat were recorded at low tide (>100m
of mudflat exposed) on 20th January 2006. Records were made at both
NHS and SPN.
4.2
Bird abundance and species
composition were compared with baseline data recorded from September/October
2001 to May 2002, as presented in the Shenzhen Western Corridor EIA
Report.
4.3
Bird species and abundance
within a 100m quadrat of exposed
mudflat were recorded at low tide (>100m
of mudflat exposed) on 20th January 2006. Records were made at both
NHS and SPN.
4.4
Surveys were also conducted at
a 500m belt transect established
at SPN, on the same date using the same methodology adopted at NHS.
4.5
Bird density within the
tideline transects at NHS and SPN was compared using the non-parametric
Mann-Whitney test, where:
HO = There
are no differences in bird densities along the tidelines at NHS and SPN.
4.6
Additionally, bird abundance
and species composition were compared with baseline data recorded from
September 2001 to May 2002, as presented in the Shenzhen Western Corridor EIA
Report.
5.1
Seven
species, Black-faced Spoonbill (Platalea minor),
Chinese Pond Heron (Ardeola bacchus), Common Kingfisher (Alcedo atthis), Curlew (Numenius arquata),
Great Egret (Casmerodius albus) ,
Little Egret (Egretta garzetta) and White-Breasted Kingfisher (Halcyon smyrnensis) were recorded from
exposed mudflats during recent surveys,
with fifteen Curlew, fourteen
Chinese Pond Heron, one Common
Kingfisher, one Little Egret, a Great Egret and a White-Breasted Kingfisher
recorded from SPN, and sixteen
Little Egret and four Black-faced Spoonbill recorded from NHS (Figure 5.1).
5.2
Compared
to the results of January 2006 surveys,
the EIA Report recorded a mean of 1.5 birds/ha and 0.9 species and 3.9 birds/ha
and 1.5 species on exposed mudflats at NHS and SPN respectively.
Figure 5.1 Comparison
of Bird Abundance and Species Composition on Exposed Mudflats: Ngau Hom Shek
and Sheung Pak Nai, January, 2006
5.3
Bird
densities recorded along tidelines were 35 birds/ha at NHS and 45 birds/ha at
SPN, with 5 species recorded at NHS
(Black-faced Spoonbill, Platalea minor; Chinese Pond Heron, Ardeola bacchus; Curlew, Numenius
arquata; Great Egret, Casmerodius
albus; Little Egret, Egretta
garzetta) and 5 species (Black-faced Spoonbill,
Platalea minor; Chinese Pond Heron, Ardeola bacchus; Curlew, Numenius
arquata; Grey Heron, Ardea cinerea and Little Egret, Egretta garzetta) recorded from SPN (Figure
5.2).
5.4
A
Mann-Whitney test found no statistically significant difference between bird
densities recorded at NHS and SPN (P = 0.449).
5.5
At NHS, bird density recorded during recent surveys (35
birds/ha) was higher than mean values presented in the EIA Report (23.2
birds/ha), whereas bird density at SPN
(45 birds/ha) was slightly lower than values presented in the EIA Report (58.2
birds/ha). At both sites, species
richness recorded during recent surveys (5 species at NHS and 5 species at SPN)
was higher to mean values presented in the EIA Report (1.8 species and 2
species recorded at NHS and SPN respectively).
Figure
5.2 Comparison of Bird Abundance and
Species Composition along Tidelines: Ngau Hom Shek and Sheung Pak Nai, January 2006
6.
Discussion and Conclusion
6.1
Bird densities and species
richness on mudflats at both the potential impact site and the control site
were low during January 2006 surveys but they are higher than the mean values
given in the EIA report. There was no evidence of construction phase
disturbance at NHS, the potential
impact site.
6.2
During surveys conducted in January
2006, bird densities along tidelines
at NHS (the potential impact site) were lower than that at SPN (the control
site). No statistically significant difference in tideline densities at NHS and
SPN was observed, and there was no
evidence of construction phase disturbance at NHS,
the potential impact site.
References
Carey, G.J., Chalmers, M.L., Diskin, D.A., Kennerley,
P.R., Leader, P.J., Leven, M.R., Lewthwaite, R.W., Melville, D.S., Turnbull,
M., and Young, L. (2001): The Avifauna of
Hong Kong. Hong Kong Bird Watching
Society, Hong Kong.
Appendix 1 – Requirements
and Event and Action Plan for that potential work disturbance to inter-tidal
bird communities monitoring works.
Work disturbance on inter-tidal bird
communities:
Distribution of feeding shorebirds on inter-tidal mudflats near construction
sites of the alignment will be studied. Distances of feeding birds on mudflat
within 500m of both
sides of the construction site will be recorded. Birds feeding on exposed
mudflats and tidelines will be recorded separately. Survey will be carried out
when more than 100m mudflat
is exposed, as in the EIA study. A graph showing the distribution pattern of
feeding birds around the construction site will be plotted. A control site will
be set up on mudflats at Sheung Pak Nai. Distribution pattern of feeding birds
on both sides of a strip of mudflat of equal width as the construction sites
will be studied in the same way as in the construction site. Distribution
patterns of birds at the construction site and control site will be compared
using statistical test. Bird abundance and species richness in the construction
site and the control site will also be compared with the baseline data of these
two locations collected during the field surveys for the EIA study (Table 3.10
& 3.11 in
Appendix 9A of the EIA
report). The data from the control site will provide information on the bird
density and composition in the outer Deep
Bay area, while the data
from the construction site can reflect the potential effect of construction
works on birds. Any changes of bird density recorded in the construction site
will be adjusted by the changes of bird density in the control site. Discussion
on any changes of species composition recorded in the construction site will
also make reference to the results from the control site. Sampling frequency
will be once per month throughout the construction phase. If a 30% net
reduction (after adjustment) of bird density was recorded in the construction
site, the ET and the on-site engineer will be alerted to any non-compliance of
mitigation measures or site practices. The monitoring frequency will also be
increased to once per week (Table 6.2) until the recorded bird density stores
and complies with the 30% allowance of Trigger level. If the net reduction
continues and exceeds 50% (allowance of Action level, see Table 6.2),
disturbance mitigation measures such as erection of disturbance barrier will be
applied. The weekly monitoring frequency will be maintained until the recorded
bird density stores and complies with the 30% allowance of Trigger level.
Table 6.2 Trigger
and Action levels for Bird density
|
Parameters
|
Trigger level
|
Action
|
Action level
|
Action
|
|
Bird density
(No./ha)
|
30% net
reduction of bird density in construction site in comparison with baseline
data in construction site from EIA filed surveys (Table 3.10 & 3.11 in Appendix 9A of the EIA report) and the change of bird
density in control site.
|
Alert the ET
and on-site engineer. Increase the monitoring frequency to weekly.
|
50% net
reduction of bird density in construction site in comparison with baseline
data in construction site from EIA filed surveys (Table 3.10 & 3.11 in Appendix 9A of the EIA report) and the change of bird
density in control site.
|
Disturbance mitigation measures such as erection of
disturbance barrier.
|