1.4.24 The Lok Ma Chau area held low numbers of Imperial Eagles, and there was some exchange between Lok Ma Chau and other sites, with individuals ranging quite widely over the study area. Numbers at Lok Ma Chau were highest in November (Figure 14).
Density (no. of ind./km2) of Imperial Eagle
over time with sites Separated
1.4.25 The variability shown at each of the six sites during the winter is summarised below in Figure 15. This variability in numbers shows a gradual decline over the course of the winter. Carey et al. (2001) noted a marked increase in numbers during January but considered this to be a result of greater observer coverage in the Deep Bay Area.
Figure 15
Average number of sightings per transect
for
Imperial Eagle over time with sites
combined
1.4.26 The uneven distribution of Imperial Eagle within the study area indicated that some habitats were preferred over others. As can be seen from Table 4, significantly higher numbers were recorded in managed wetlands (i.e. Mai Po). There was an avoidance of developed areas and inter-tidal mudflats. The distribution of the various habitats within the study area is shown in Figure 54.
Table 4
Imperial Eagle - Mann-Whitney Test results – a particular habitat vs all the other pooled habitats. Significant values are in bold.
|
Habitat |
c2 |
DF |
p |
Comparison |
|
Creek |
0.33 |
1 |
0.5659 |
Creek = others |
|
Developed area |
5.71 |
1 |
0.0168 |
Developed area < others |
|
Fish pond |
2.79 |
1 |
0.0950 |
Fish pond = others |
|
Inter-tidal mudflat |
7.67 |
1 |
0.0056 |
Inter-tidal mudflat < others |
|
Mangrove |
0.01 |
1 |
0.9388 |
Mangrove = others |
|
Managed wetland |
26.28 |
1 |
<0.0001 |
Managed wetland > others |
|
Secondary woodland/ Shrub land |
1.64 |
1 |
0.2001 |
Secondary woodland/Shrub land = others |
1.4.27 During the surveys time budget data were collected on five dates; totally 105 minutes were collected. The results of this are presented in Figure 15.
Imperial Eagle - Activity
at Lok Ma Chau, Winter 2000-01
1.4.28 The most frequent activity was perching (80%). This is typical of large eagles, and especially Imperial, which, when hunting, often adopts a sit and wait technique. One individual recorded feeding was found to be eating a Eurasian Wigeon Anas penelope.
Japanese Yellow Bunting Emberiza sulphurata
Status
1.4.29 The Japanese Yellow Bunting is a globally threatened species listed as Vulnerable by BirdLife International (2000, 2001).
Status In Hong Kong
1.4.30 In Hong Kong Japanese Yellow Bunting is a scarce and irregular spring passage migrant. Just over 50% of observations in Hong Kong have been in the Deep Bay area where the species is usually seen in or near to dense cover: on overgrown landfill sites, well-vegetated fish pond bunds, in Horsetail Trees Casuarina equisetifolia with an extensive understorey of Common Lantana Lantana camara, on the edges of gei wai or even in the edges of mangroves. Away from Deep Bay, it is found in agricultural land, shrubland edges and again around fishponds and on landfill sites. In recent years Long Valley has been a favoured site, and there are also records from scattered localities on Hong Kong Island, Dong Ping Chau, Cheung Chau, at fishponds near Tai Po Kau Tsuen, Ho Chung and Shuen Wan. Passage occurs during a rather short period with a marked peak in the first two weeks of April. The earliest records are of single birds at Mai Po (HKBR 1989:9) and on Cheung Chau, both on 27 March 1989, and the latest report is of one bird at Long Valley on 28 April 1996. Small parties of birds are not infrequent, and larger numbers occur together during years with influxes; the highest counts are of 15 birds at Tsim Bei Tsui on 11 April 1993 and 17 at Long Valley on 6 April 1996 (Carey et al. 2001).
Status during the
baseline surveys
Lok Ma Chau
1.4.31 Not recorded.
San Tin
1.4.32 Not recorded.
Long Valley
1.4.33 Not recorded
1.4.34 It should be noted that two species listed as Globally Threatened in ERM (1999b) and the previous EIA Report (Binnie 1999), Schrenck’s Bittern Ixobrychus eurhythmus and Red-billed Starling Sturnus sericeus were listed as Globally Threatened by Collar et al. (1994) but not by BirdLife International (2000, 2001). These species are, however, retained as Species of Conservation Importance in the present EIA by virtue of their status as being of Restricted Range in Hong Kong and having a Regionally Important population in Hong Kong, respectively (see below).
Regionally Important Species
Great Cormorant Phalacrocorax carbo
Status
1.4.35 The Great Cormorant is a winter visitor to Hong Kong that is abundant in Deep Bay from October to early April. Most birds feed in Deep Bay, often in large flocks that occasionally hold up to 2500 birds; a significant proportion also feed in the fish ponds of Deep Bay, and much smaller numbers feed and roost in other coastal waters such as those around Lantau and, to a lesser extent, Cheung Chau.
1.4.36 Numbers of Great Cormorants wintering in Hong Kong have increased markedly since 1981 when censuses of the population present in Deep Bay were first carried out. Deep Bay now holds one of the largest wintering populations of Great Cormorant in Asia, and the most significant known concentration of wintering birds east of Turkmenistan (see Perennou et al. 1994). The five-year mean of peak counts between the winters of 1994-95 and 1998-99 was 6791 (Carey and Young 1998); thus, based on figures in Rose and Scott (1997), Deep Bay regularly supports approximately 1% of the northern hemisphere population, 1.2% of the P.c. sinensis population, 6.8% of the regional population and 0.4% of the world population (Carey et al. 2001).
Status during the
baseline surveys
Lok Ma Chau
1.4.37 Whilst numbers were generally low (<50 individuals) throughout the survey period, 478 were recorded on 13 November 2000 (Figure 16). Distribution and average number per visit are shown in Figure 55.
San Tin
1.4.38 Whilst numbers were generally low (<30 individuals) throughout the survey period, 329 were recorded on 7 March 2001 (Figure 16). Distribution and average number per visit are shown in Figure 55.
Great Cormorant - Number of individuals per visit at
Lok Ma Chau and San Tin winter 2000-01
Long Valley
1.4.39 Not recorded.
Grey Heron Ardea cinerea
Status
1.4.40 In Hong Kong, the Grey Heron is an abundant winter visitor to Deep Bay, and is scarce in summer, with occasional breeding records. Numbers wintering have increased from 732 in 1987 to a peak of 1962 birds in February 1996. Grey Herons occur mainly in Deep Bay where they feed in both intertidal and fish pond or gei wai areas, and a substantial part of the population appears mainly to feed nocturnally. Rose and Scott (1997) estimate the east-southeast Asian population to lie in the range 25,000 to one million birds. The five-year mean of peak winter counts from 1994-95 to 1998-99 is 1280, which means that Deep Bay on average supports 0.13 to 5.2% of the regional population (Carey et al. 2001).
Status in the baseline
surveys
Lok Ma Chau
1.4.41 Numbers fluctuated markedly in response to drain down of fishponds and reduced levels of human disturbance. The highest count was 113 on 28 February 2001 (Figure 17). Distribution and average number per visit are shown in Figure 56.
San Tin
1.4.42 Numbers were generally lower at San Tin with a peak of 80 on 3 January 2001(Figure 17). Distribution and average number per visit are shown in Figure 56.
Grey Heron - Number of individuals per visit at Lok Ma
Chau and
San Tin winter 2000-01
Long Valley
1.4.43 At Long Valley numbers were low, with one or two recorded on six dates (Figure 18). Distribution and average number per visit are shown in Figure 57.
Abundance of Grey Heron at Long Valley during 2000-01
Great Egret Egretta alba
Status
1.4.44 In Hong Kong, the Great Egret is common to abundant all year, with small numbers breeding. The highest numbers occur during the winter, with the peak count being 1073 in Deep Bay on 12 December 1993. Records are mainly from the wetlands around Mai Po and Inner Deep Bay, Starling Inlet and Shuen Wan. Rose and Scott (1997) estimate the east/southeast Asian population to lie in the range 10,000 to 100,000 birds. The five-year mean of peak winter counts from 1994-95 to 1998-99 is 490, which means that Deep Bay on average supports approximately 0.5 to 5% of the regional population.
Status in the baseline
surveys
Lok Ma Chau
1.4.45 At Lok Ma Chau numbers fluctuated markedly (Figure 19) largely in response to drain down of fishponds. The peak count was 125 on 28 September 2000. Distribution and average number per visit are shown in Figure 58.
San Tin
1.4.46 The peak count recorded at San Tin, 134 on 14 March 2001, was slightly higher than at Lok Ma Chau (Figure 19). Distribution and average number per visit are shown in Figure 58.
Great Egret - Number of individuals per visit at
Lok Ma Chau and San Tin winter 2000-01
Long Valley
1.4.47 Numbers were low at Long Valley, with one to two present on five dates (Figure 20). Distribution and average number per visit are shown in Figure 59.
Great Egret - Number of individuals per visit at Long
Valley 2000-01
Little Egret Egretta garzetta
Status
1.4.48 In Hong Kong the Little Egret is an abundant species present all year, most birds probably resident. Little Egrets occur in lowlying wet or coastal areas throughout Hong Kong. They appear to have adapted well to the increased impact of man on the environment, and to still be present in numbers in such heavily anthropogenic areas as Sha Tin and Victoria Harbour. In 1958 they were recorded feeding in rice fields, but since that habitat has disappeared from Hong Kong, they are now mainly recorded feeding in a variety of wetland habitats such as the banks of rivers and streams, mudflats and fishponds and traditional gei wai shrimp ponds. In the northwestern New Territories, drained down fish ponds and gei wai are a particularly important winter feeding habitat for Little Egrets, with 900 birds recorded in a single drained fish pond by Young and Chan (1997), and up to 1680 birds in a drained gei wai on 20 October 1994 (Ma 1997). Rose and Scott (1997) estimate the east-southeast Asian population to lie in the range 100,000 to one million birds. The five-year mean of peak winter counts from the winter of 1994-95 to 1998-99 is 1140, which means that Deep Bay possibly supports over 1% of the regional population (Carey et al. 2001).
Status in the baseline
surveys
Lok Ma Chau
1.4.49 At Lok Ma Chau most counts were of less than 200 birds, with the exception being a count of 694 on 28 Sep 2000 (Figure 21). The count of 694 was largely made up of 680 birds on a single pond. These had been disturbed from a nearby drained pond. Distribution and average number per visit are shown in Figure 60.
San Tin
1.4.50 At San Tin numbers were generally lower, with a peak of 138 on 28 March 2001 (Figure 21). Distribution and average number per visit are shown in Figure 60.
Little Egret - Number of individuals per visit at
Lok Ma Chau and San Tin winter 2000-01
Long Valley