1. MONITORING REQUIREMENTS
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. MONITORING EQUIPMENT
2.1 Equipment used for monitoring included a 20-60x spotting scope, 10x42 binoculars, and Hand-held GPS.
3. MONITORING LOCATIONS
3.1 Monitoring was conducted at two locations, Ngau Hom Shek (NHS) and Sheung Pak Nai (SPN), as shown in Figure 3.1. 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
Intertidal Mudflat Monitoring
4.1 Bird species and abundance within a 100m2 quadrat of exposed mudflat were recorded at low tide (>100m of mudflat exposed) on 15th January 2004. Records were made at both NHS and SPN (Figure 3.1).
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.
Tideline Monitoring
4.3 Surveys at NHS were conducted along a 10m wide belt transect centred along the tideline on 15th January 2004. The transect extended 250m either side of the bridge alignment (Figure 3.1). The transect was divided into 50m sections, and bird density and species composition within each section was recorded. Surveys were conducted at low tide, when at least 100m of mudflat was exposed.
4.4 Surveys were also conducted at a 500m belt transect established at SPN (Fig. 3.1), 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.
RESULTS
Intertidal Mudflats
5.1
Densities recorded
on exposed mudflats were 6 birds/ha at NHS and 5 birds/ha at SPN. One species
(Chinese Pond Heron, Ardeola bacchus) was recorded at both sites,
with Little Egret (Egretta garzetta) and White-breasted Kingfisher (Halcyon
smyrnensis) recorded from NHS, and Great Egret (Casmerodius albus)
and Common Sandpiper (Actitis hypoleucos) recorded from SPN (Figure
5.1).
5.2
Bird density
recorded during recent surveys were higher than mean values presented in the
EIA Report. A mean of 1.5 birds/ha and 3.9 birds/ha were recorded in the EIA
Report at NHS and SPN respectively, compared to 6 birds/ha and 5 birds/ha
recorded at NHS and SPN during monitoring conducted in January 2004. Species
richness was higher at both sites than mean values presented in the EIA Report.
A mean of 0.9 species and 1.5 species were recorded in the EIA Report at NHS
and SPN respectively, compared to 3 species at both NHS and SPN recorded during
monitoring conducted in January 2004.
Figure 5.1 – Comparison of Bird Abundance
and Species Composition on Exposed Mudflats: Ngau Hom Shek and Sheung Pak Nai,
Jan. 2004
Tideline
5.3
Bird densities
recorded along tidelines were 34 birds/ha and 230 birds/ha at NHS and SPN
respectively, with 3 species recorded at NHS, and 2 species at SPN (Figure
5.2). The three species recorded at NHS comprised Little Egret (Egretta
garzetta), Great Egret (Casmerodius albus) and Grey Heron (Ardea
cinerea). Records at SPN were dominated by a very large flock of 113 Curlew
(Pandion haliaetus); the only other records were of 2 Little Egret.
5.4
A Mann-Whitney
found no statistically significant difference between bird densities recorded
at NHS and SPN (P = 0.791).
5.5
At NHS, bird
density and species richness recorded during recent surveys were higher than
mean values presented in the EIA Report. A mean of 23.2 birds/ha and 1.8
species were recorded in the EIA Report, compared to 34 birds/ha and 3 species
recorded during monitoring conducted in January 2004. At SPN, bird densities
recorded during recent surveys (230 birds/ha) were much higher than mean values
recorded in the EIA Report (58.2 birds/ha). Species richness was identical,
with 2 species recorded during recent surveys, compared with a mean of 2.0
species recorded in the EIA Report.
Figure 5.2 – Comparison of Bird Abundance
and Species Composition Along Tidelines: Ngau Hom Shek and Sheung Pak Nai, Jan.
2004.
6.
DISCUSSION AND
CONCLUSION
Intertidal Mudflats
6.1 Bird density and species richness were higher on exposed mudflats at both the potential impact site (NHS) and the control site (SPN) than mean values given in the EIA Report.
6.2 During surveys conducted in January 2004, similar densities and species richness were recorded at NHS and SPN; there was no evidence of construction phase disturbance at NHS, the potential impact site.
Tideline
6.3 At NHS, bird densities recorded along the tideline were higher in January 2004 than mean values given in the EIA Report. Bird tideline densities recorded at SPN were much higher than mean values given in the EIA Report.
6.4 Although during recent surveys bird densities were higher along tidelines at the control site (SPN) than at the potential impact site (NHS), this difference was not considered to result from construction phase disturbance for the following reasons:
· Densities of birds at NHS during recent surveys were higher than pre-construction phase densities presented in the EIA Report (34 birds/ha compared to 23.2 birds/ha)
· Surveys conducted for the EIA Report indicate that mean densities at NHS were generally lower than at SPN before construction phase activities began (23.2 birds/ha compared to 58.2 birds/ha). The results of recent surveys would appear to follow this trend.
· The very high bird densities recorded at SPN during January 2004 surveys were entirely due to the large flock of Curlew (113 birds) recorded feeding along a small stretch (150m) of the tideline. According to the EIA Report, this species was often recorded in substantial numbers at SPN during baseline surveys (s3.4.7, Appendix 9A of the EIA Report refers). The preference of this species for SPN was therefore established before the commencement of construction works at NHS, and it can thus be concluded that the large overall difference in densities resulting from the Curlew flock at SPN was not related to construction activities at NHS.
· The difference in bird densities at NHS and SPN during recent surveys was not statistically significant.
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.
|