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 16th April 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 16th April, 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 4 birds/ha at NHS and 3 birds/ha at SPN. Two species
(Little Egret, Egretta garzetta, and White-breasted Kingfisher, Halcyon
smyrnensis) were recorded at both sites, with an additional record of a
single Chinese Pond Heron, Ardeola bacchus from NHS (Figure 5.1).
5.2
At NHS, bird
densities recorded during recent surveys were higher than mean values presented
in the EIA Report, with a mean of 1.5 birds/ha recorded in the EIA Report,
compared to 4 birds/ha recorded during monitoring conducted in April 2004. Bird
densities recorded at SPN during recent monitoring were slightly lower than
those recorded in the EIA Report (3 birds/ha compared to 3.9 birds/ha). 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 NHS and 2 species at SPN
recorded during monitoring conducted in April 2004.
Figure 5.1 – Comparison of Bird Abundance
and Species Composition on Exposed Mudflats: Ngau Hom Shek and Sheung Pak Nai,
April 2004
Tideline
5.3
Bird densities
recorded along tidelines were 36 birds/ha and 28 birds/ha at NHS and SPN
respectively, with 4 species recorded at NHS, and 3 species at SPN (Figure
5.2). Species recorded at both sites comprised Little Egret (Egretta
garzetta), Great Egret (Casmerodius albus), and White-breasted
Kingfisher (Halcyon smyrnensis). An additional single Chinese Pond Heron
(Ardeola bacchus) was recorded from NHS.
5.4
A Mann-Whitney
found no statistically significant difference between bird densities recorded
at NHS and SPN (P = 1.0).
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 36 birds/ha and 4 species
recorded during monitoring conducted in April 2004. At SPN, bird densities
recorded during recent surveys (28 birds/ha) were lower than mean values
recorded in the EIA Report (58.2 birds/ha). Species richness was similar, with
3 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,
April 2004.
6.
DISCUSSION AND
CONCLUSION
Intertidal Mudflats
6.1 Bird density and species richness on exposed mudflats at NHS were higher than mean values given in the EIA Report. At SPN, densities were slightly lower and species richness higher than mean values given in the EIA Report.
6.2 During surveys conducted in April 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 April 2004 than mean values given in the EIA Report. Bird tideline densities recorded at SPN were lower than mean values given in the EIA Report.
6.4 The higher densities recorded at NHS can largely be attributed to a flock of nine Little Egret and Great Egret feeding approximately 100-200m northeast of the alignment.
6.5 Tideline densities recorded in April 2004 at SPN were much lower than records from the same site during the winter season. For example, the density recorded in February 2004 was 262 birds/ha, compared with 28 birds/ha in both March and April 2004. The decline in bird densities at SPN can be attributed to a fall in the number of Curlews recorded at the site. 118 Curlews were recorded from SPN on 13th February 2004, compared with just two recorded on 24th March 2004, and none recorded in April 2004 surveys. This decline is consistent with general abundance patterns of Curlews in Hong Kong. Curlews are common winter and early spring visitors to Hong Kong, with peak numbers generally occurring in the first two weeks of February (Carey et al, 2001). Records of this species decline through late February and March as much of the population migrates to the north (ibid.).
6.6 During surveys conducted in April 2004, 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.