Threat Thursday: the "Critically Endangered" Brenton Blue 

Threat Thursday features the Brenton Blue Orachrysops niobe. This "Critically Endangered" butterfly is the flagship species of the COREL programme of LepSoc (Lepidopterists' Society of Africa). The COREL custodian of the Brenton Blue is Dave Edge, a resident of Knysna. LepSoc and several other NGOs initiated a major campaign during the 1990s which resulted in the proclamation, in July 2003, of the 1.4 ha Brenton Blue Butterfly Reserve (BBBR) to conserve the butterfly in its last known habitat.

The BBBR is managed by a committee established by the Brenton Blue Trust and chaired by CapeNature with representatives from all the stakeholders. A management plan has been established and is continuously refined by ongoing research. The population is regularly monitored and has been found to vary between 50 to 280 adults per brood, with two broods per year (November and February). The butterfly population fluctuates with the varying abundances of its host plant Indigofera erecta and its host ant Camponotus baynei. Expansion of the BBBR is therefore planned onto a 20 ha of public open space to the north of the BBBR, in order to increase the butterfly population. This is a medium-term project, and habitat alteration to make it suitable for the host plant to grow and the host ant to take up residence has commenced.

The Brenton Blue butterfly originally had a wider distribution, and also occurred near Nature's Valley (about 60 km to the east). Attempts have been made to reintroduce the species at a fynbos reserve site here where it once was present. Habitat restoration work had been undertaken. But this initiative did not meet with success because of the poor condition of the host plant population at the site, the small area of suitable habitat on the site, and the absence of the host ant.

The "butterfly atlas" – a partnership project between LepSoc, ADU and SANBI – is not far from launching its pre-publication offer. Watch out for this. It will be the most important publication in the history of butterfly studies in South Africa.

The fundamental underpinning prerequisite for effective conservation of a species is a knowledge of its distribution. The butterfly atlas project is ongoing, as we continue to map the 21st century distributions, through the ADU virtual museum. Upload any photos of butterflies you have to vmus.adu.org.za.

The top picture shows the butterfly (Justin Bode). The lower picture shows the Brenton Blue Butterfly Reserve near Knysna (Dave Edge).

Les Underhill
2012-10-11

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