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 100m quadrat of exposed mudflat were recorded at low tide (>100m of mudflat exposed) on 18th August 2005. 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               Bird species and abundance within a 100m quadrat of exposed mudflat were recorded at low tide (>100m of mudflat exposed) on 18th August 2005. Records were made at both NHS and SPN (Figure 3.1).

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.                  Monitoring Results

Intertidal Mudflat Monitoring

5.1               Only one species, Little Egret (Egretta garzetta), was recorded from exposed mudflats during recent surveys, with a single Little Egret recorded from SPN, and no birds recorded from NHS (Figure 5.1).

5.2               Compared to the results of July 2005 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, 2005

Tideline

5.3               Bird densities recorded along tidelines were 26 birds/ha at NHS and 2 birds/ha at SPN, with 2 species recorded at NHS (Little Egret; Egretta garzetta and Great Egret, Casmerodius albus) and a single Little Egret 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 = 0.052).

5.5               At NHS, bird density recorded during recent surveys (26 birds/ha) was slightly higher than mean values presented in the EIA Report (23.2 birds/ha), whereas bird density at SPN (2 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 (2 species at NHS and 1 species at SPN) was similar 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, August 2005

 

6.                  Discussion and Conclusion

Intertidal Mudflats

6.1               Bird densities on mudflats at both the potential impact site and the control site were very low during August 2005 surveys, with only a single bird recorded from the mudflat at SPN.  There was no evidence of construction phase disturbance at NHS, the potential impact site.

Tideline

6.2               During surveys conducted in August 2005, bird densities along tidelines at NHS (the potential impact site) were much higher than those recorded at SPN (the control site), although this difference was not statistically significant. 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.