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 21st November 2003. 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 21st November 2003. 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 9 birds/ha at both NHS and SPN, with two species
(Little Egret, Egretta garzetta; Chinese Pond Heron, Ardeola bacchus)
recorded at both sites (Figure 5.1).
5.2
Bird density
recorded during recent surveys were substantially 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 9 birds/ha
at both sites recorded during monitoring conducted in November 2003. Species
richness was slightly 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 2 species at both sites
recorded during monitoring conducted in November 2003.
Figure 5.1 – Comparison of Bird Abundance
and Species Composition on Exposed Mudflats: Ngau Hom Shek and Sheung Pak Nai,
Nov. 2003
Tideline
5.3
Bird densities
recorded along tidelines were 32 birds/ha and 58 birds/ha at NHS and SPN
respectively, with 3 species recorded at NHS, and 6 species at SPN (Figure
5.2). All of the birds recorded at NHS were ardeids, whereas only 58% of the
birds recorded at SPN were ardeids. Non-ardeid species at SPN comprised a small
flock of 7 Curlew (Pandion haliaetus), and 5 Common Sandpipers (Actitis
hypoleucos).
5.4
A Mann-Whitney
found no statistically significant difference between bird densities recorded
at NHS and SPN (P = 0.069).
5.5
At NHS, bird
density and species richness recorded during recent surveys were slightly
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 32 birds/ha and 3
species recorded during monitoring conducted in November 2003. At SPN, bird
densities recorded during recent surveys (58 birds/ha) were almost the same as
mean values in the EIA Report (58.2 birds/ha). Species richness was higher,
with 6 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,
(Nov. 2003)
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 Nov. 2003, identical 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 Nov. 2003 than mean values given in the EIA Report. Bird tideline densities recorded at SPN were similar to 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 (32 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 difference in bird densities at NHS and SPN during recent surveys was not statistically significant.