SANBI

Rationale (Changed due to Same category and criteria)

This endemic taxon is range-restricted in the Western Cape Province, South Africa, with a very small EOO (5.1 km<sup>2</sup>) and AOO (16 km<sup>2</sup>) and one of its subpopulations (and a location) appears to have been lost over the last three years. This (inland) fynbos subpopulation was also an important genetic resource, since it appears to have specialised ecological adaptations differing from the subpopulations closer to the sea shore. The loss of this genetic variation could make it extremely difficult for the taxon to recolonise fynbos sites in the future. The taxon thus qualifies globally under the IUCN criteria as Critically Endangered under criterion B.

Distribution

Endemic to the Western Cape Province in South Africa, only known from the Knysna area. Used to be widespread on the eastern Knysna Head, from sea level westwards inland for approximately 7 km across the Woodbourne farm, and what is now the Sparrebosch golf estate, but is now restricted to two small subpopulations on the coast east of Coney Glen just above sea level.

Decline

"The landscape at the inland habitats has become more and more overgrown because of absence of natural fires and grazing animals, and consequently the inland butterfly subpopulations have become virtually extinct.\nThe coastal sites closer to the Knysna Eastern Head have been destroyed or transformed by housing and as a result of increased tourism traffic across beaches and rocks. Further east the only human traffic is fishermen, who are causing an ongoing littering problem, even as far as the butterfly sites."

Habitat View more ecological information

Population trend

Trend

No individuals have been seen at the inland (fynbos) site for three years and it is functionally extinct. The two extant subpopulations close to the seashore therefore constitute the only survivors of this once widespread and plentiful species.

Threats

This taxon was originally quite widespread and common from the eastern Knysna Heads both down to near sea level and on the north-facing fynbos covered slopes. Further to the east plantation forestry in earlier years probably eradicated many subpopulations. Most of this large metapopulation has been lost since 1962 through incremental habitat destruction and degradation caused by housing and road developments, a golf course development, and excessive grazing by sheep on the remaining agricultural land. At present the last subpopulation still extant in the fynbos has virtually disappeared because its habitat has become overgrown. This is because there are no grazing animals, either wild or domestic, and fire is being excluded because of the threat it poses to valuable properties. Another threat is the presence of increasing amounts of alien plants, such as hakea and pines, at this fynbos site. There are two extant subpopulations near the seashore which, even if they survive for several decades, will eventually be threatened later this century by sea level rise.

Conservation

A research program into the life history and ecology of the taxon has been completed. This yielded accurate population counts, which showed that numbers at the (inland) fynbos site were declining. The owners of the land on which the last surviving subpopulation in a fynbos habitat occurred agreed to leave it undisturbed, but refused to implement active habitat management, such as the removal of alien plants, introduction of grazing animals and a block burning program. The habitat continued to deteriorate and this subpopulation has now virtually disappeared. Efforts will continue to persuade the landowners to implement the recommended management actions, but after the large Knysna June 2017 fire, fear of fire amongst property owners has continued to grow, although allowing this area to become overgrown with thicket vegetation will itself pose an increasing fire risk. Ideally this fynbos site should be declared as a nature reserve and be managed on sound ecological principles. On the positive side, the research also resulted in the discovery of the coastal subpopulations, which seem to be secure and stable at present, although they may eventually succumb to sea level rise. These subpopulations could be a source of butterflies to repopulate the inland sites if the landowners are persuaded to manage them properly. Searches will therefore be made further to the east along the coast to see if other subpopulations can be found, even as far as Noetzie and the eastern side of the Noetzie River (Sinclair Nature Reserve).

References

[@book{772,
 address = {Johannesburg &Cape Town},
 author = {Mecenero, S., Ball, J.B., Edge, D.A., Hamer, M.L., Henning, G.A., Krüger, M., Pringle, E.L., Terblanche, R.F. & Williams, M.C. (eds)},
 publisher = {Saftronics (pty) Ltd and  Animal Demography Unit, University of Cape Town},
 title = {Conservation assessment of butterflies of South Africa, Lesotho and Swaziland: Red List and Atlas.},
 year = {2013}
}
,@book{772,
 address = {Pretoria},
 author = {Henning, G.A., Terblanche, R.F. & Ball, J.B. (eds)},
 publisher = {South African National Biodiversity Institute},
 title = {South African Red Data Book: butterflies. SANBI Biodiversity Series},
 year = {2009}
}
,@article{772,
 author = {SANBI},
 journal = {South African National Biodiversity Institute},
 pages = {0},
 title = { Vegetation Map of South Africa, Lesotho and Swaziland [vector geospatial dataset] 2012. Available from the Biodiversity GIS website.},
 volume = {0},
 year = {2012}
}
,@book{882,
 address = {Cape Town, South Africa},
 author = {Woodhall, S.E.},
 publisher = {Struik},
 title = {Field Guide to Butterflies of South Africa.},
 year = {2005}
}
,@book{890,
 address = {Pretoria},
 author = {Henning, S.F. & Henning, G.A.},
 publisher = {Council for Scientific and Industrial Research},
 title = {South Africa Red Data Book - Butterflies.},
 year = {1989}
}
,@book{893,
 author = {Williams, M.C.},
 publisher = {CD-ROM. Available from the author at mark.williams[at]up.ac.za.},
 title = {Butterflies and skippers of the Afrotropical Region.},
 year = {2016}
}
,@article{895,
 author = {Edge, D.A.},
 journal = {Metamorphosis},
 number = {2.0},
 pages = {28--46},
 title = {Butterfly conservation in the southern Cape, South Africa.},
 volume = {16},
 year = {2005}
}
,@book{10844,
 address = {Halfway House},
 author = {Williams, M.C.},
 publisher = {Southern Book Publishers},
 title = {Butterflies of Southern Africa: A Field Guide.},
 year = {1994}
}
,@article{21749,
 author = {Heath, A. & Pringle, E.L.},
 journal = {Metamorphosis},
 pages = {90--151},
 title = {A review of the southern African genus <i>Thestor<i> Hübner (Lepidoptera: Lycaenidae: Miletinae)},
 volume = {15},
 year = {2004}
}
,@article{168302868,
 author = {Trimen, R.},
 journal = {Transactions of the Entomological Society of London},
 pages = {347–363},
 title = {Description of twelve new species of south Africaan Lepidoptera Rhopalocera.},
 volume = {1883},
 year = {1883}
}
,@article{168302868,
 author = {Bazin, E.A. & Edge, D.A.},
 journal = {Journal of Insect Conservation},
 pages = {349--357},
 title = {The ecology and conservation of <i>Thestor brachycerus brachycerus</i> (Trimen, 1883): an aphytophagous miletine butterfly from South Africa.},
 volume = {19},
 year = {2015}
}
,]

How to cite this assessment

See the partners page

Send feedback about this assessment to SANBI

Red List of South African Species