Holiday houses or habitat: conservation of the Brenton Blue niobe (Trimen) (: ), in Knysna,

Letitia X. Silberbauer* David R. Britton^ 'School of Biological Sciences, University of Wollongong, Northfields Avenue, Wollongong, New South Wales 2255 ^Department of Zoology, University of the Witwatersrand, Private Bag 3, WITS 2050 South Africa 'Address for correspondence: Division of Agronomy and Soil Science, University of New England, Armidale, New South Wales 2351

In 1996, the South African transitional government drafted legislation to conserve biodiversity. Around this time lepidopterists, other conservationists and the Lepidopterists Society of Africa publicised the plight of the endangered Brenton Blue Butterfly in South Africa.

This butterfly is restricted to a small locality in the midst of a new housing development. The Downloaded from http://meridian.allenpress.com/rrimo/book/chapter-pdf/2643157/rzsnsw_1999_064.pdf by guest on 27 September 2021 Brenton Blue Butterfly became a test case for the power of the new conservation legislation. During the summer of 1996-97, a multi-disciplinary team of researchers was contracted by the Endangered Wildlife Trust of Southern Africa to determine the status, conservation priorities, ecological requirements of the butterfly, and to identify factors contributing to its population decline. Habitat loss appears to be the main factor contributing to population decline. Management of the population will focus on maintaining food plant populations while preventing any further detrimental anthropogenic disturbances.

INTRODUCTION 3. to environmentally assess the site, specifi- cally the distribution of the food plant, The Brenton Blue Butterfly erecta (Thunb.); Trimen (Lepidoptera: Lycaenidae), is a highly endangered species which is now restricted to 4. to determine whether a symbiotic relation- a single locality (Brenton-on-Sea) near Knysna, ship exists between , caterpillars South Africa. The species is extinct at its only and ants (as occurs in related butterfly other known locality (Nature's Valley), and species); land development for holiday houses at 5. to survey other areas to confirm that Brenton-on-Sea threatened the remaining Brenton-on-Sea is the only remaining population. Its life-history and taxonomy population of the butterfly, and to find were examined only recently (Henning and areas suitable for extending the butterfly's Henning 1994; Edge and Pringle 1996; range. Williams 1996). However, the life history is only partially described, as larval stages have yet to be observed in the field. METHODS A multidisciplinary ecological study was A team consisting of lepidopterists (D. commissioned to provide a scientifically-based Britton, D. Edge, J. Ball and E. Pringle), an opinion on the importance of the Brenton-on- ecologist (L. Silberbauer), botanists (R. Sea site for the survival of the species. The Lubke, D. Hoare and J. Victor) and an ant time available was limited to part of the specialist (H. Robertson) was assembled to adult flight period, because of the pressing determine status, critical habitat, and potential need for reports for land-managers and land management directions for O. niobe. The legislators. The aim of this paper is to demon- team coordinated efforts and expertise to strate that even a short-term study can provide determine key ecological factors in the short useful information, but the authors acknow- time available. Most of these results are ledge that it is in no way a replacement for presented in Britton and Silberbauer (1997); long-term studies. this paper mainly presents the results for which the authors were directly responsible, The ecological aims of this project were: namely for surveying all life stages of the species on site, surveying the distribution of 1. to establish the conservation status of the the food plant on site, searching the Brenton butterfly; Peninsula for other potential populations of 2. to determine the distribution and behaviour the O. niobe, finding and observing larval of adults and immature stages of O. niobe stages of O. niobe, and to determine critical on site at Brenton-on-Sea; habitat for O. niobe.

Pp. 394-97 in The Other 99%. The Conservation and Biodiversity of Invertebrates ed by Winston Ponder and Daniel Lunney, 1999 Transactions of the Royal Zoological Society of New South Wales, Mosman 2088. We attempted to observe immature stages of 0. niobe by searching the foliage of I. erecta. Searches for larvae were undertaken during daylight and at night (between dusk and 2230 hr) to maximize our chances of observing feeding larvae.

RESULTS Females were observed ovipositing on I. erecta throughout the site. Females ignored the two other species of Indigofera present, although both sexes were observed feeding on nectar from these plant species. 0. niobe was not observed breeding elsewhere on the Brenton peninsula, although a single female was observed flying about 200 m north of Downloaded from http://meridian.allenpress.com/rrimo/book/chapter-pdf/2643157/rzsnsw_1999_064.pdf by guest on 27 September 2021 the Brenton-on-Sea site (H. Robertson, pers. comm.). Ninety-nine eggs were located. Most eggs Copulating Brenton Blue Butterflies Orachrysops niobe were laid singly under the leaves, but one was (Lepidoptera: Lycaenidae) Knysna, Western Cape Province, South Africa; the male is on the right. found on a stem of the plant, several were found singly on the upper surface of leaves, and several were laid in pairs on the same The site where 0. niobe occurs at Brenton- leaf. We found only two damaged eggs On-Sea (~38°S, 24°E) is approximately 2.3 ha and none that were parasitized. The distri- in size. It is a steep, south-facing, ancient bution of eggs, along with the presence of dune covered by a mixture of fynbos heath- 1. erecta throughout the site (as measured land, invading coastal forest species and by presence/absence in 1 m^ quadrats) is shown introduced weeds (Lubke et al. 1997). Historic- in Figure 1. The presence of eggs seemed ally it was thought to have been burnt to be dictated by the presence of dense stands regularly, although the frequency of burns is of I. erecta. Areas with less than 5% covering unknown (R. Lubke, pers. comm.). of I. erecta are not shown in Figure 1, but were surveyed and found to contain no 0. niobe Adult butterflies were surveyed by taking eggs. Further inspection of other regions of a census of males. Females were cryptic and the Brenton peninsula indicated that there difficult to find. Males actively patrolled the were very few areas with I. erecta occurring site along established pathways, so it was in densities that the Brenton-on-Sea site possible to survey them by capturing individuals supported, and such sites were small in area as they passed and holding them until no and isolated. further males were seen; at this stage all the captured males were released. Total We found no larvae in the field despite population/day was taken as double the making diurnal and nocturnal observations of number of males observed by assuming an plants with numerous eggs. Larval feeding equal sex ratio. Male flight behaviour was habits of 0. niobe in the field, and the predictable, and we were confident that we saw presence or absence of attendant ants are still the majority of males present on each day of unknown. observation. The number of male 0. niobe captured was Food plants and eggs were surveyed by low, with a maximum of 10 individuals flying running a transect along the contour of the on 15 December, 1996 (estimated from five site at three metre intervals. Quadrats (1 m^) males). A previous estimate was of only six on each side of the transect were examined for individuals on 12 December, 1996. None of I. erecta, a low-growing herb. If food plants our counts returned more than 12 individuals were present within quadrats, then they were present, whether by simply observing males searched for 0. niobe eggs. When eggs were flying past, or by capturing and holding males located, the plant was marked by placing a in vials. The population size during the small flag of red insulation tape on a bamboo spring/summer of 1996-97 was unusually low skewer adjacent to the plant. Each flag was (D. Edge, pers. comm.), possibly because given an identifying number and the details of abnormally low winter rainfall in 1996. of egg placement, developmental status Adult females were also observed mating (hatched or unhatched or damaged) were and ovipositing, but their behaviour made it recorded. difficult to observe them in the field.

June 1999 The Other 99%. The Conservation and Biodiversity of Invertebrates 395 Downloaded from http://meridian.allenpress.com/rrimo/book/chapter-pdf/2643157/rzsnsw_1999_064.pdf by guest on 27 September 2021

Figure 1. Cadastral map of the breeding site at Brenton-on-Sea showing the locations of Orachrysops niobe eggs (black squares) and food plant present at density >5% per m^ (vertical hatching). The area in the top right hand corner (stippling) had eggs and food plant present, but there was insufficient time to survey these two blocks in detail. Scale bar shows 15 m.

DISCUSSION ensure survival of O. niobe. There should be no further development of land on or The study confirmed that the active breeding near the site and there should be an active colony of Orachrysops niobe at Brenton-on-Sea management program of the food plant on is confined to the known site. The site was site. Further research on the behaviour and unique on the Brenton-on-Sea peninsula ecology of immature stages of the butterfly because of a large cover of dense Indigofera and ecology of the food-plant is essential. erecta, the food plant for the butterfly. Eggs of 0. niobe were found only on I. erecta plants The South African government enacted its in areas where the food plant was abundant biodiversity protection legislation, which has and dense. It is evident that the butterfly halted further development at the Brenton-on- requires an abundant presence of its food Sea site, proclaiming it as a protected area. plant. The butterfly species, and its reserve, are important symbols of the new South African Our failure to observe larvae in the field government's dedication to the preservation of suggests that they are cryptic and may have a biodiversity within South Africa, and have short daily feeding period. It will be crucial become flagship species for invertebrate to find larvae in the field to establish whether conservation in South Africa. or not there is a symbiotic relationship with an ant species, such as that which occurs for the closely related Lepidochrysops (Clark ACKNOWLEDGEMENTS and Dickson 1971). Our thanks go to the Endangered Wild- It is difficult to draw many conclusions, life Trust of Southern Africa and Conrad but the information presented here indicates Steenkamp who commissioned the study. that the Brenton-on-Sea site is crucial to Many thanks to Hamish Robertson, Roy

396 The Other 99%. The Conservation and Biodiversity of Invertebrates June 1999 Lubke, David Hoare, Janine Victor, David Edge, D. A. and Pringle, E. L., 1996. Notes on the Edge, Ernest Pringle, and Jonathan Ball who natural history of the Brenton Blue, Orachrysops niobe formed the scientific team. Thanks to the (Trimen) (Lepidoptera: Lycaenidae). Metamorphosis 7: 109-20 + 2 plates. Department of Zoology at the University of the Witwatersrand for providing facilities and Henning, G. A. and Henning, D. F., 1994. Taxonomy to the many sponsors for logistical and of Orachrysops. In Pennington's Butterflies of Southern Africa, 2""' edition ed by E. L. Pringle, G. A. Henning financial support. and J. B. Ball. Publ. Struik Winchester: Cape Town.

Lubke, R., Hoare, D. and Victor, J., 1997. The vegetation REFERENCES and floristics of the habitat of the Brenton Blue Butterfly. Pp. 30-64 in The Life-history, Ecology and Britton, D. R. and Silberbauer, L. X., 1997. The Conservation of the Brenton Blue Butterfly, Orachrysops life-history, ecology and conservation of the niobe (Trimen) (Lycaenidae) at Brenton-On-Sea ed by Brenton Blue Butterfly, Orachrysops niobe (Trimen) D. R. Britton and L. X. Silberbauer. Research report (Lycaenidae) at Brenton-On-Sea. Research report for for the Endangered Wildlife Trust of Southern the Endangered Wildlife Trust of Southern Africa. Africa. Clark, G. C. and Dickson, C. G. C., 1971. Life Williams, M. C., 1996. Report on research findings Histories of the South African Lycaenid Butterflies. The concerning the life history and ecology of the

Entomological Work of Gowan C. Clark and C. G. C. Brenton Blue (Orachrysops niobe). Metamorphosis 7: Downloaded from http://meridian.allenpress.com/rrimo/book/chapter-pdf/2643157/rzsnsw_1999_064.pdf by guest on 27 September 2021 Dickson. Publ. Purnell. 3-7.

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