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.
4.1
Bird species and abundance
within a 100m quadrat
of exposed mudflat were recorded at low tide (>100m of mudflat exposed) on 18th August 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 18th August 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.
Monitoring Results
5.1
Three
species, Chinese Pond Heron (Ardeola bacchus),
Little Egret (Egretta garzetta) and White-throated Kingfisher (Halcyon smyrnensis) were recorded from
exposed mudflats during recent surveys,
with five Chinese Pond Heron, one Little
Egret and one White-throated Kingfisher recorded from SPN,
and eight Little Egret and two White-throated Kingfisher recorded from NHS
(Figure 5.1).
5.2
Compared
to the results of August 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, August,
2006
5.3
Bird
densities recorded along tidelines were 17 birds/ha at NHS and 12 birds/ha at
SPN, with 3 species recorded at NHS
(Great Egret, Casmerodius albus; Little
Egret, Egretta garzetta; Chinese Pond Heron,
Ardeola bacchus) and 2 species
(Great Egret, Casmerodius albus;
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 = 0.970).
5.5
At NHS, bird density recorded during recent surveys (17
birds/ha) was lower than mean values presented in the EIA Report (23.2
birds/ha), whereas bird density at SPN
(12 birds/ha) was much lower than values presented in the EIA Report (58.2
birds/ha). At both sites, species
richness recorded during recent surveys (3 species at NHS and 2 species at SPN)
were almost the same as the 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, August 2006
6.1
Bird densities and species
richness on mudflats at both the potential impact site and the control site
were low during August 2006 surveys. Both of the bird densities in SPN and NHS
were 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 late
August 2006, bird density at the
control site is much lower than the mean values presented in the EIA report. The
main reason is that there is a fall in the number of Curlews recorded on the
site. 26 Curlews were recorded from SPN on 20th January 2006 while
no Curlew was recorded this month. This decline is consistent to the abundance
pattern of Curlews in Hong Kong because Curlews are common winter visitors in
Hong Kong but most of them migrate to the north during late February and March.
6.3
In this survey, bird density along tidelines at NHS (the potential
impact site) was lower than the mean values presented in the EIA report but it
was slightly higher than that at SPN (the control site). There is no
statistically significant difference in tideline densities at NHS and SPN, and there was no evidence of construction phase
disturbance at NHS, the potential impact
site.
Reference
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.
|