Birdwing butterfly (Troides helena) established in Lantau
Birdwing butterfly (Troides Helena) established in Lantau
Further to the brief paper on the two Hong Kong Birdwing butterflies published in this issue of Porcupine! (page 10), a trip was made to Tung Chung
from the Po Lin Monastery on 7 September, 1997
Five Troides Helena including 4 males and 1 female were observed within a period of twenty minutes along the footpath from Po Lin to the middle pagoda towards Tung Chung. A few Pachliopta aristolochiae (Common Rose butterfly) were also seen flying in the vicinity.
A type of Aristolochia vine was spotted alongside the footpath. On searching, many larvae of P. aristolochiae were found feeding on the vines. This vine was later confirmed by Prof. William Xing from Kadoorie Farm & Botanic Garden to be Aristolochia fordiana. It is suspected that this is also the host plant for Troides Helena in Po Lin, as the normal host, A tagala was not found at the site.
Aristolochia fordiana is common in this area, and if Troides Helena is, like Pachliota aristolochiae, making use of this species as a host plant, it suggests that the Birdwing population can become firmly established at this locality.
James J. Young
P.9
Butterfly status and flight periods -addenda
George Walthew's paper "The status and flight periods of Hong Kong butterflies" which appeared in the last issue of Porcupine! suffered some inadvertent truncation. Accidentally cut off the list was Polygonia c-aureum, a vagrant recorded once in November 1990.
Two further additions were made to the Hong Kong list in 1997; collected during the HKU Biodiversity Survey and subsequently identified by Dr. Mike Bascombe. They are Aeromachus pygmaea (Fabricius) (Hesperiidae: Hesperiinae), recorded in April at Cheung Sheung, and Euploea sylvester (Fabricius) (Nymphalidae: Danainae), recorded in June on Kat 0 Chau. The status of both species may be defined as "rare" using Walthew's (1997) criteria. Euploea sylvester is already recorded from Guangdong Province. However, Aeromachus pygmaea had not been recorded from Chinese territory prior to April 1997. Nevertheless a small population seems to be established at Cheung Sheung: members of the Hong Kong Lepidoptera Group visited the site in April of this year, and were able to reconfirm the presence of this tiny skipper Interestingly, this species was recorded at Gu Tian Nature Reserve, Guangdong, a few days before the first Hong Kong specimen was collected (Fellowes & Hau, 1997).
And there's more...
Two additional species of butterfly were discovered at Fung Yuen in May 1998, by Mr. Shingo Murakami. Tagiades menaka (Moore) (Hesperiidae: Pyrginae) was recorded for the first time on 2 May, and Papilio dialis Leech (Papilionidae: Papilioninae) was taken on 16 May, bringing to nine the number of Papilio species known from Hong Kong. Neither species has been recorded from Guangdong, but both are known from Guangxi. James Young reports that he has collected larvae of Ampittia virgata, which is already known from Guangdong and Guangxi, but is yet another new record for Hong Kong.
Graham Reels
Fellowes, J R & Hau, C. H. (1997). A Faunal Survey of Nine Forest Reserves in Tropical South China, with a Review of Conservation Priorities in the Region. Kadoorie Farm & Botanic Garden, Hong Kong. 151 pp.
Walthew, G. (1997). The status and flight periods of Hong Kong butterflies. Porcupine! 16: 34-37.
P.9
A brief note on the distribution and conservation of Birdwing butterflies in Hong Kong
Both Troides Helena (Linnaeus) and Troides aeacus (C. & R. Felder) are large butterflies of the Papilionidae family. They are the only two representatives of the so called Birdwing butterflies in Hong Kong. Troides Helena is the commoner of the two with T. aeacus having first been recorded only about 10 years ago.
These two species cover a vast area across Nepal, India, South China, Vietnam, Thailand, Malaysia and Indonesia Though they have a wide distribution, they are not common in Hong Kong. The range of the two butterflies overlaps but Troides Helena in Hong Kong is close to its northern limit. It is seldom found north of Guangdong Province. Troides aeacus on the other hand has a much wider distribution than T. Helena It is found as far north as Hubei, and in Taiwan as well.
The two species are found in various scattered locations throughout Hong Kong. Stable populations are known from three locations in the New Territories: one in Sai Kung peninsula near Po Lo Che, one at Shan Liu near Tai Po and one at Kadoorie Farm & Botanic Garden. Both species are found in Kadoorie Farm and at the Tai Po site, but Troides aeacus appears to be absent from the Sai Kung site The butterflies are multivoltine and have many generations in a year. They are generally on the wing from March to November Fung Yuen Village SSSI in Tai Po was in the past a sanctuary for Birdwings. Now they have almost gone as the formerly abundant foodplants of the butterflies (Aristolochia tagala) in Fung Yuen have all but disappeared. At the same time, the village has undergone increasing development. Other sightings of Birdwings have included Tai Po Kau Nature Reserve in Tai Po, Hok Tau Reservoir in Fanling, Tai Mei Tuk near Plover Cove, Sha Lo Tung, She Shan in Lam Tsuen, and Ho Chung and Wong Chuk Yeung in Sai Kung.
Birdwings also occur on Lantau Island. Many positive sightings have been made on the path from Po Lin Temple to Tung Chung (see page 9). Troides Helena has been recorded on Sunset Peak and a Troides male has been spotted at Tong Fuk. One may even find Birdwings on Hong Kong Island as the foodplant appears to exist in the Tai Tam area surrounding Hong Kong Parkview. The Common Rose butterfly, Pachliopta aricholochiae (Fabricius), which has the same foodplant as Troides, was recorded in Tai Tam Country Park very near to Hong Kong Parkview in 1994.
Conservation
Birdwings are huge, spectacular butterflies, as a result of which they are very popular with collectors. Over-collecting has led to a decline in Birdwing numbers across much of their range. However, this situation does not seem to exist in Hong Kong, where Birdwing butterflies are protected by law. In fact, the Birdwings in Hong Kong appear to have increased in numbers. Any future depletion of the Troides species in Hong Kong will probably be caused by the ever increasing rural development, which threatens the breeding sites. The Troides in particular are very selective in their food source, feeding only on the fruits and leaves of Aristolochia, a climbing vine found scattered across the New Territories. This plant is also protected by law in Hong Kong. As their appetites are enormous, large numbers of foodplants are required to sustain a healthy Birdwing population. Efforts have thus been directed into conserving the populations at Kadoorie Farm and Shan Liu, where more Aristolochia vines have been planted to provide an ample food source for the butterflies. New breeding sites have been planned with the planting of the hostplants for the butterflies, which will at the same time be artificially reared and transferred to such sites for regeneration.
Conclusion
Birdwing butterflies have been recorded from various scattered locations in Hong Kong. However, only a handful of breeding sites are known to exist. Such sites could easily be destroyed either by further rural development or by natural causes. Attention should be drawn to the need to protect such breeding sites for the survival of the butterflies so that they can be preserved and flourish in the years to come.
James J. Young & G.T. Reels
P.10
Status of Hong Kong butterflies - an update
In the last issue of Porcupine! George Walthew published an article on the status and flight periods of Hong Kong butterflies. This was based on presence/absence data from 170 one-kilometre grid squares, surveyed from 1989 to 1996, for 225 butterfly species. Status was defined by a scale of six cohorts ranging from "vagrant" to "very common" (see Walthew (1997) for details.). During the course of the Hong Kong Biodiversity Survey (conducted by the DEB through 1996 and 1997), similar data were gathered from 70 sites, most of which were of approximately one square kilometre (some islands visited were of a smaller area). Applying Walthew's criteria to these data, the following results were obtained: rarer 17 spp.; commoner 94 spp.; unchanged 114 spp.
The Biodiversity Survey findings were in agreement with Walthew (1997) for 114 of the 225 species, including all of those classified by Walthew as "very common" or "vagrant". The status of 99 species was different by one cohort (e.g. a shift from "uncommon" to "common", or from "rare" to "very rare", etc.), with 85 species slightly commoner and 14 species slightly rarer than recorded by Walthew (1997). Such relatively minor discrepancies are perhaps to be expected from results obtained by different recorders employing (presumably) different sampling effort. However, a more marked difference in status was recorded for 12 species, which are listed below (along with comments made by Marsh (1968) and Hill et al (1978) to give an historical perspective):
Status 1996 - 1997 (Biodiversity survey data) Status 1989 - 1996 (Walthew, 1997) [Status according to Hill et al (1978)] [Status according to Marsh (1968)) Nymphalidae - Nymphalinae Cyrestis thyodamas
very common uncommon "rare" not recorded in HK Lycaenidae - Lycaeninae Heliophorus epicles
very common uncommon "uncommon" "not common" Lycaenidae - Polyommatinae Jamides celeno
very rare uncommon "rare" "extremely rare" Zizina otis very common uncommon "uncommon" "extremely common" Pieridae - Coliadinae Eurema blanda
common rare "rare" not common but possibly under-recorded Eurema brigitta very rare uncommon "rare" "locally common" Papilionidae Pachliopta aristolochiae
very rare uncommon "rare" "common... but... restricted" Hesperiidae - Coeliadinae Hasora chromus
uncommon very rare "rare" status not indicated Hesperiidae - Hesperiinae
Baoris farri
common very rare "uncommon" "quite common" Parnara ganga common rare "rare" uncommon / rare Pelopidas mathias common rare "rare" rare Udaspes folus common rare "uncommon" "quite common" These discrepancies cannot be so easily dismissed, and suggest genuine shifts in status over time. Or do they? Butterfly recording can be a very hit-or-miss process, often governed by finding the right place (a particular host plant, for instance) at the right time (some butterflies are very active throughout the day; most are not. Many are strongly seasonal.), in the right weather conditions (butterflies abhor rain and cold), in the right year (some species may fluctuate in abundance from year to year; see for example Butterfly populations at Kadoorie In October 1997 - this issue). Also, neither Marsh (1968) nor Hill et al (1978) give explanations of their status criteria, and their information can not be treated as directly comparable to that gathered by Walthew (1997) and the Biodiversity Survey. However, the element of chance can not be responsible for all the differences observed between these workers. The data for Cyrestis thyodamas, at least, suggest a real long term increase over the past three decades for this species, which was first recorded in Hong Kong in 1971. Given the environmental changes which Hong Kong is experiencing (increasing urbanisation, agricultural land falling to disuse, existing forests slowly maturing) it is hardly surprising that our butterfly fauna should change, too. (Note, also, that the number of butterfly species recorded in Hong Kong has risen by a remarkable 20% in the last 30 years.). Distinguishing short term fluctuations from long term trends is the real challenge. To do that, a continuous, coordinated approach to butterfly monitoring needs to be established. The recent creation of the Hong Kong Lepidoptera Group gives hope that such a monitoring programme could soon become a reality.
G. T. REELS & GEORGE WALTHEW
Hill, D.S , 6. Johnston and M.J. Bascombe (1978). Annotated checklist of Hong Kong butterflies. Mem. H.K Nat. Hist. Soc. 11
Marsh , J.C.S. (1968). Hong Kong Butterflies. (2nd edition). The Shell Company of Hong Kong Limited.
Walthew, G. (1997). The status and flight periods of Hong Kong butterflies. Porcupine! 16: 34-37.
P.11
Butterfly Populations at Kadoorie in October1997
During 1996 I conducted a survey of butterflies at KFBG and KARC. I revisited Kadoorie from 8 to 14 October in 1997 but on only two of the days was the weather suitable for gathering data comparable to that of October 1996. On the two days I walked a 3.5 km circular route starting between 09:00 hrs and 09:30 hrs as I had in 1996. From KARC at 200 m altitude, the walk took me up to Kwun Yam Shan at 546 m and back down to KARC. This was the same route walked in 1996 and a map of the route and explanation of the method can be found in Walthew, 1997 (The Butterflies of Kadoorie: A report on the butterflies at Kadoorie Farm & Botanic Gardens, and Kadoorie Agricultural Research Centre, Hong Kong, in 1996).
On the two visits, I saw 61 species on the first occasion and 60 on the second. This is very similar to my species counts from mid-October 1996 (the mean number of species for mid-October 1996 was 63.25). However, when it came to numbers of butterflies the situation was unexpectedly different. The mean count for mid-October 1997 was significantly greater than that of mid-October 1996. When the counts were broken down into family and sub-family I could see that the increase in numbers could be accounted for amongst the families Papilionidae and Pieridae, and the subfamily Danainae (and possibly the Satyrinae) from the Nymphalidae. There was no significant increase in the numbers of Nymphalinae, Charaxinae, Lycaenidae (including the Riodininae) or Hesperiidae.
In all, 47 of the 73 butterfly species I saw on the two walks at Kadoorie in October 1997 showed an increase in numbers compared to 1996, but just 6 species accounted for 53% of the total increase. These were (in order of importance): Euploea midamus, Papilio memnon, Eurema blanda, Papilio helenus, Delias pasithoe, and Eurema hecabe. After removing those species I saw in 1996 but not in 1997 (to eliminate bias, as I only made two visits in 1997, and they were close together in time) a comparison of the counts showed:
Nymphalidae: 19 species increased, 14 species decreased, 3 species unchanged
Lycaenidae: 6 species increased, 2 species decreased
Pieridae: 8 species increased, 1 species unchanged
Papilionidae: 8 species increased, 3 species decreased
Hesperiidae: 6 species increased, 2 species decreased, 1 species unchanged
Although it might be expected that the populations of butterfly species vary from year to year, with such a large fluctuation in numbers occurring simultaneously over a number of butterfly families, some broad mechanism is likely to be involved. One such mechanism is weather, and the summer of 1997 was the wettest on record. Exactly how or why the families involved were affected is unknown but a number of mechanisms could be involved (e.g. an increase in larval food or its palatability; or a decrease in predation or parasitisation of eggs, larvae, pupae, or adults).
George Walthew
P.12
Wintering roosts of Danainae (Crow and Tiger butterflies)
The Hong Kong Lepidoptera Group is currently working on a survey of the roosts of Danainae butterflies in Hong Kong in view of conservation / increasing our knowledge of the natural history of these species.
Everyone who regularly spent time in the countryside in December / January will have seen these congregations of butterflies, yet despite the publicity given to the Monarch butterfly in North America, little is known about related species in Hong Kong.
The HKLG would be grateful for any information on the locations of wintering roosts of Crow and Tiger butterflies in Hong Kong. Please send such information to the HKLG, c/o Paul Lau, G.P.O. Box 4667, Central, Hong Kong, or E-mail plphotog@hk.gin.net.
P.12
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