3.                  INSECTS, HERPETOFAUNA AND MAMMALS IN LONG VALLEY

 

3.1              Introduction

 

3.1.1        Field visits were undertaken in June, July, August, September, October and November 2000, and were then suspended for four months before being resumed in April and May 2001. Between December and March insect and herpetofauna activity is very low and it was considered unnecessary to continue surveys during this period. Following preliminary site visits, 5 formal transect routes were established. These transects were used for both insect and herpetofauna surveys, and are located near to, but not on, the development footprint (see Figure 1).

 

3.2              Methodology

 

Insect

 

3.2.1        Insects (dragonflies and butterflies) were surveyed on two mornings per month, on fine weather days. Transects were walked at a fixed pace and all individuals observed along or on either side of the transect (within a radius of approximately 5m) were identified, sexed (where possible) and counted. Care was required to ensure that individuals were not counted more than once. Some dragonfly males, in particular, have the habit of patrolling back and forth along a fixed territory, and may therefore be encountered on several occasions during the same transect walk. To complement transect surveys, general surveys of the whole site were made.

 

3.2.2        Field equipment consisted of close-focussing binoculars to aid identification of small, distant or evasive species, and a long-handled collecting net in case of encounters with species which require examination in the hand (on-site) or, in the case of problematic specimens, temporary collection for later identification.

 

Herpetofauna

 

3.2.3        Herpetofauna (reptiles and amphibians) were surveyed on two afternoons per month, on fine weather days. The same transects as used in the insect surveys were followed and all individuals observed were identified, sexed (where possible/appropriate) and counted. Active searching of suitable microhabitats along the transects (e.g. huts, stones or wooden boards on the ground, tree trunks and other upright structures, small water impoundments, etc.), and pauses to wait for re-emergence of glimpsed animals, meant that it was not possible to sustain a fixed pace during herpetofauna surveys. To complement transect surveys, general surveys of the whole site were made. This procedure was repeated on two evenings per month, during which identifications were made by torchlight and/or, in the case of breeding amphibians, by auditory detection.

 

Mammals

 

3.2.4        No specific mammal surveys were carried out. However, any mammals or mammal signs (such as scats) observed during the course of other surveys were recorded.

 

Transect

 

T1. (North section of study area). This transect commences at the eastern end of the northern bund of field 105 and continues alongside an irrigation channel in a westerly direction along the northern bund of fields 104, 107, 109, 110 and 119, ending at the junction of fields 119, 122, 123 and 127.

 

T2. (North section of study area). Commencing at the northeast corner of field 124, the transect continues alongside an irrigation channel in a southwest direction along the northern bunds of fields 125, 137 and 154, ending at the northwest corner of field 154.

 

T3. (North and South sections of study area). A circular transect commencing at the southeast corner of field 163 (North section) and continuing anti-clockwise around the perimeter of this field and the adjacent South section field 125.

 

T4. (South section of study area). A circular transect commencing at the southeast corner of field 119 and continuing anti-clockwise around the perimeter of this field and the western perimeter of the adjacent field 118, further continuing eastwards along the northern bund of field 111.

 

T5. (South section of study area). A circular transect commencing at the northeast corner of field 85 and continuing anti-clockwise around the perimeter of this field and the adjacent field 84.

 

3.3              Results - transect surveys

 

Dragonflies

 

3.3.1        Tables (3.1-3.5) showing results of transect surveys are given below. Graphs showing abundance of particular species are given in Appendix D.

 

Table 3.1 Dragonflies at transect 1

 

Species/date

15.6.00

22.6

23.7

29.7

11.8

23.8

2.9

12.9

16.10

28.10

15.11

29.11

10.4.01

29.4

5.5

21.5

Anax parthenope

1'

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Brachythemis contaminata

 

2'2"

2'

 

1'

 

1'1"

 

 

 

 

 

 

 

 

 

Crocothemis servilia

1'

 

 

 

 

 

 

 

1'

 

 

 

 

 

 

 

Hydrobasileus croceus

 

 

 

 

1'

 

 

 

 

 

 

 

 

 

 

 

Ischnura senegalensis

 

3

 

 

 

 

 

 

 

 

2

 

2

 

 

1

Orthetrum pruinosum

 

 

1'

 

1'

 

1"

 

 

3'1"

1

2

 

2

3

2

Orthetrum sabina

6

6

8

3

4

2

4

2

5

3

 

 

 

2

1

3

Pantala flavescens

8

7

5

14

12

25

3

1

2

7

4

2

1

 

2

3

Tramea virginia

2

 

 

1

 

 

 

 

 

 

 

 

 

 

1

 

' male; " female

Table 3.2 Dragonflies at transect 2

 

Species/date

15.6.00

22.6

23.7

29.7

11.8

23.8

2.9

12.9

16.10

28.10

15.11

29.11

10.4.01

29.4

5.5

21.5

Anax parthenope

 

 

 

 

 

 

 

 

1'

 

 

 

 

 

 

 

Brachythemis contaminata

 

2'

 

 

1'

 

 

 

 

 

 

 

 

 

 

 

Crocothemis servilia

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2

Ischnura senegalensis

2

2

 

 

 

 

 

 

1

 

 

 

 

 

 

 

Orthetrum pruinosum

1'1"

1'

 

1'

 

 

 

 

 

 

1

 

 

2

5

1

Orthetrum sabina

3

7

4

5

5

2

3

2

1

 

 

 

 

 

2

3

Pantala flavescens

4

9

3

5

1

30+

4

 

1

1

 

2

 

3

3

1

Rhyothemis variegata

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Tramea virginia

 

 

1

 

 

 

 

 

 

 

 

 

 

1

 

 

' male; " female

 

Table 3.3 Dragonflies at transect 3

 

Species/date

15.6.00

22.6

23.7

29.7

11.8

23.8

2.9

12.9

16.10

28.10

15.11

29.11

10.4.01

29.4

5.5

21.5

Brachythemis contaminata

5'2"

6'2"

2'

1'1"

 

1'

 

 

 

 

 

 

 

 

 

 

Crocothemis servilia

 

1'

 

 

2'

 

 

 

 

 

 

 

 

 

 

 

Ischnura senegalensis

11

2

 

1

 

 

 

 

 

 

 

 

 

 

 

 

Orthetrum pruinosum

 

1'

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Orthetrum sabina

8

5

6

3

5

3

5

4

2

 

2

 

2

 

 

1

Pantala flavescens

13

3

8

5

9

50+

3

1

3

5

1

2

 

2

3

2

Tramea virginia

1

 

1

 

 

 

 

 

 

 

 

 

 

2

1

3

' male; " female

 

Table 3.4 Dragonflies at transect 4

 

Species/date

15.6.00

22.6

23.7

29.7

11.8

23.8

2.9

12.9

16.10

28.10

15.11

29.11

10.4.01

29.4

5.5

21.5

Crocothemis servilia

2'

 

 

 

2'

 

 

 

 

 

 

 

 

 

 

1

Ischnura senegalensis

 

 

 

 

 

 

 

 

 

 

 

 

 

 

3

 

Orthetrum sabina

5

3

4

1

3

5

2

2

1

 

1

 

 

 

4

2

Pantala flavescens

5

8

3

11

4

22

7

3

6

 

2

1

2

3

9

3

Rhyothemis variegata

3

 

1

2

 

1

 

 

 

 

 

 

 

 

 

 

Tramea virginia

1

1

 

 

3

 

 

 

 

 

1

 

 

 

 

1

' male; " female

 

Table 3.5 Dragonflies at transect 5

 

 Species/date

15.6.00

22.6

23.7

29.7

11.8

23.8

2.9

12.9

16.10

28.10

15.11

29.11

10.4.01

29.4

5.5

21.5

Anax parthenope

 

 

 

1'

 

 

 

 

 

 

 

 

 

 

 

 

Brachythemis contaminata

4'3"

5'1"

2'

4'

1'

4'1"

1'1"

 

 

 

 

 

2

1

 

 

Crocothemis servilia

3'

2'

 

 

2'

 

 

 

 

 

 

 

 

 

 

 

Diplacodes trivialis

 

 

 

 

 

1'

 

 

 

 

 

 

 

 

 

 

Ischnura senegalensis

2

8

 

3

 

 

 

 

 

 

 

 

 

 

 

 

Orthetrum pruinosum

 

2'

1"

 

1'

 

 

1'

 

 

 

1

 

 

3

2

Orthetrum sabina

5

3

4

4

2

 

1

2

1

1

 

 

 

 

 

 

Pantala flavescens

7

3

2

 

8

50+

5

 

2

3

2

 

2

 

5

4

Potamarcha congener

 

 

 

 

 

1

 

 

 

 

 

 

 

 

 

 

Tramea virginia

 

1

 

 

 

 

 

 

 

1

1

 

 

 

 

 

' male; " female

 

 

3.3.2        Notable dragonfly sightings at Long Valley made close to but just outside of the transects (i.e. of species not otherwise recorded) included the following:

 

Ceriagrion auranticum - 1 individual field N106 22 June. 1 individual field S81 23 July; 1 individual field N120 23 July. 1 individual field N115 23 August. A common and widespread species (Wilson, 1997).

 

Copera marginipes - 1 individual field N20 28 October. A common and widespread species (Wilson, 1997).

 

Anaciaeschna jaspidea - 2 individuals seen at dusk over fields N112 and N114 on 15 June. 1 individual seen at dusk over field N108 on 23 July. 2 individuals over fields N111 and N104 on 11 August, also at dusk. This is a crepuscular aeshnid species absent from transects due to day-time (morning) scheduling of transect surveys. A common lowland species locally (Wilson, 1997).

 

Acisoma panorpoides - 1 individual (male) observed at field S75 on 22 June. A common lowland libellulid species (Wilson, 1997).

 

Table 3.6

Summary of Dragonfly Diversity and Abundance for Transects

 

 

T1

T2

T3

T4

T5

Mean no. spp. per visit

3.25

2.5

2.69

2.5

3

Mean dragonfly abundance per visit

11.69

8.13

12.5

9

11.34

Total no. Species

9

9

7

6

10

 

Discussion

 

3.3.3        No species of conservation concern were recorded during the surveys. The most notable dragonfly sighting was of a single male Potamarcha congener at Transect 5 (western edge of field S85) on 23 August. This libellulid species is described as locally uncommon by Wilson (1997). However, the fact that only one individual was seen at Long Valley between June 2000 and May 2001 indicates that the site is probably not an important one for this species.

 

3.3.4        A total of 16 species were recorded. Transect 5 had the greatest overall number of species (10) including the uncommon Potamarcha congener, and transect 4 the lowest (6) (Table 3.6). Transects 1 and 5 had the highest average number of species per visit. The most frequently encountered species was the ubiquitous, cosmopolitan libellulid Pantala flavescens. This species is capable of breeding in almost any freshwater habitat, and is a migrant which frequently exhibits swarming behaviour (as observed at Long Valley on 23 August). Orthetrum sabina, another widespread and locally abundant species, was the second-commonest species at Long Valley over the study period, being present in moderate numbers at each transect throughout.

 

3.3.5        The irrigation channels along transects 1 and 2 had largely dried up by October, as had the marshy disused fields at transect 3. This is reflected in the general decline in numbers of individuals observed after August.

 

3.3.6        It should be noted that the scheduling of the surveys was such that crepuscular or eocrepuscular species were under-recorded. In addition to Anaciaeschna jaspidea, at least two other species (Tholymis tillarga and Zyxomma petiolatum) are likely to be present within the study area but were overlooked because they are primarily active at dawn and/or dusk. However, none of these species is of conservation significance in Hong Kong.

 

Butterflies

 

3.3.7        Results for all five transects are summarised in one table below (Table 3.7).

 

Table 3.7 Butterfly species recorded at transects

 

Species/date

15.6.00

22.6

23.7

29.7

11.8

23.8

2.9

12.9

16.10

28.10

15.11

29.11

10.4.01

29.4

5.5

21.5

Ariadne ariadne

 

 

 

 

 

1(T2)

 

 

 

 

 

 

 

 

 

4(T3)

Catopsilia pomona

1(T2)

 

 

 

 

1(T3)

1(T4)

 

 

1(T1)

 

 

 

 

 

 

 

Catopsilia pyranthe

 

 

 

 

 

 

1(T1)

 

 

 

 

 

 

 

1(T4)

 

Danaus chrysippus

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1(T4)

Danaus genutia

 

 

 

 

 

 

 

 

 

 

1(T2)

1(T3)

 

 

 

 

 

Delias pasithoe

 

 

 

 

 

 

 

 

 

 

1(T4)

 

 

 

 

 

Euploea core

 

 

 

 

1(T1)

 

 

 

 

1(T1)

1(T5)

 

 

 

 

 

 

Eurema hecabe

 

2(T4)

 

 

 

3(T4)

1(T4)

 

2(T4)

 

 

1(T2)

 

 

 

 

Graphium sarpedon

 

 

 

 

 

1(T2)

 

 

 

 

 

 

 

 

 

1(T3)

Hypolimnas bolina

 

1(T1)

 

 

1(T4)

1(T5)

 

 

 

 

 

 

 

 

 

 

Hypolimnas misippus

 

 

 

 

1(T4)

1(T4)

 

 

1(T4)

 

 

 

 

 

 

 

Junonia almana

 

 

 

 

 

 

 

 

 

 

1(T3)

 

 

 

 

 

Mycalesis mineus

 

 

1(T4)

 

 

1(T1)

 

 

 

1(T3)

 

1(T4)

 

 

1(T3)

1(T3)

Papilio clytia

 

 

 

 

 

 

 

 

2(T4)

 

 

 

 

 

 

1(T4)

Papilio demoleus

 

 

 

 

1(T1)

1(T4)

 

 

 

 

 

1(T4)

 

 

 

 

 

Papilio polytes

1(T1)

 

 

 

 

1(T2)

 

 

 

 

 

 

 

1(T3)

 

 

Pieris canidia

 

1(T2)

1(T4)

 

 

 

 

 

 

1(T1)

1(T2)

2(T3)

1(T5)

 

 

 

 

1(T1)

2(T4)

2(T5)

2(T1)

1(T2)

1(T3)

2(T5)

1(T1)

3(T3)

1(T4)

Vanessa indica

 

 

 

 

 

1(T4)

 

 

 

1(T4)

 

 

 

 

 

 

Zizeeria maha

 

2(T4)

 

4(T4)

 

 

 

 

 

1(T4)

2(T5)

2(T5)

 

 

 

 

 

 

3.3.8        No additional species were encountered within the study area which were not also recorded from at least one of the transects.

 

Discussion

 

3.3.9        Only 19 species were recorded at Long Valley over the period June 2000 to May 2001. The most notable records were those of the Danaid Eggfly, Hypolimnas misippus, which is normally rare in Hong Kong (see Walthew 1997), but is more common in occasional years (e.g. Bascombe et al., 1999). It has been recorded in several localities across the New Territories in 2000 (pers. obs.). At Long Valley, single individuals were recorded on 3 of the ten visits (11 and 23 August, and 16 October) at transect 4.

 

3.3.10    All other species encountered are common in Hong Kong, with the exception of the uncommon Plain Tiger, Danaus chrysippus, of which one individual was encountered at transect 4.

 

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