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 14th February 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              Surveys at NHS were conducted along a 10m wide belt transect centred along the tideline on 14th February, 2005. 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 4 birds/ha at NHS and 5 birds/ha at SPN. Little Egret (Egretta garzetta) were recorded at both sites. Three Chinese Pond Heron (Ardeola bacchus) were recorded from SPN, and a single White-breasted Kingfisher (Halcyon smyrnensis) was recorded from NHS (Figure 5.1).

5.2              Bird densities and species richness recorded at both sites in February 2005 were higher than values presented in the EIA Report. For NHS, values presented in the EIA Report were 1.5 birds/ha and a mean of 0.9 species compared to 4 birds/ha and 2 species recorded during recent surveys. For SPN values presented in the EIA Report were 3.9 birds/ha and a mean of 1.5 species compared to 5 birds/ha and 2 species recorded during recent surveys.

Figure 5.1 – Comparison of Bird Abundance and Species Composition on Exposed Mudflats: Ngau Hom Shek and Sheung Pak Nai, February 2005

Tideline

5.3              Bird densities recorded along tidelines were 44 birds/ha at NHS and 38 birds/ha at SPN, with 6 species recorded from NHS and 4 species from SPN. Species recorded at both sites comprised Little Egret (Egretta garzetta), Great Egret (Casmerodius albus), Chinese Pond Heron (Ardeola bacchus) and Curlew (Numenius arquata). Additional single records of Northern Pintail (Anas acuta) and Black-faced Spoonbill (Platalea minor) were made from NHS (Figure 5.2).

5.4              A Mann-Whitney 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 was much higher than the mean value presented in the EIA Report (44 birds/ha compared to a mean of 23.2 birds/ha), and species richness was also higher (6 species compared to a mean of 1.8 species). At SPN, bird densities recorded during recent surveys (38 birds/ha) were slightly lower than mean values recorded in the EIA Report (58.2 birds/ha). Species richness was higher, with 4 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, Febraury 2005.

 

6.                  DISCUSSION AND CONCLUSION

Intertidal Mudflats

6.1              Bird densities on exposed mudflats at NHS were similar to those recorded at SPN. Densities and species richness were higher than mean values given for NHS in the EIA Report. There was no apparent construction phase disturbance to avifauna feeding on mudflats at NHS.

Tideline

6.2              At NHS, bird densities and species richness recorded along the tideline in February 2005 were higher than mean values given in the EIA Report.

 

6.3              During surveys conducted in February 2005, 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.