THE BRENTON BLUE BUTTERFLY RESERVE

The home of one of the rarest butterflies in the world, the Brenton Blue Butterfly Reserve (BBBR), is marked by a single signpost (see Figures 1 and 2, below). Although the BBBR effectively came into being in early 1998, it was only proclaimed as a Special Nature Reserve on 4 July 2003. Knee-high poles indicate the boundary of the nature reserve.

The site extends over approximately 2ha and contains a mixture of coastal fynbos and coastal forest. The Brenton Blue shares its home with a wide variety of other insects, as well as mammal and bird species. For a full checklist, click here.
© D A Edge
Figure 1 - The Brenton Blue butterfly reserve

© D A Edge
Figure 2 - The Brenton Blue butterfly reserve
Location
The reserve is nearly 1.5 hectares in area, and lies between W K Grobler Drive in the north and Fynbosoord in the south (see Figure 3). Its western and eastern boundaries are adjacent to residential properties. It lies at an altitude between 90 and 115 metres above sea level, and slopes in a southerly direction. For a map showing how to find the reserve, click here.

© D A Edge
Figure 3 – Map of the Brenton Blue butterfly reserve

Natural features
Geologically, the reserve is sited on an ancient dune whose core has become compacted into rock, overlain by wind blown sand deposits and a shallow soil layer (0.5 - 2.0 m deep). The climate is very mild (average 12.5 – 23.5 ēC), with abundant year-round rainfall (annual average 750mm), and frequent sea fog and mists.

The vegetation is a complex mosaic of candlewood thickets and asteraceous fynbos. The reserve contains a large population of the food plant of the Brenton Blue butterfly, a small plant in the pea family with pink flowers (pictured to the right - scientific name Indigofera erecta).

© D A Edge
Figure 4 – Indigofera erecta

© D A Edge
Figure 5 – Typical path
Controlled management
Management policy has been cautious, taking great care not to do anything that could harm the butterfly populations or its food plant. It became clear by early 2000 that some interventions were necessary since the reserve was seemingly becoming overgrown with thicket elements, and the butterfly population was in decline.

Consequently, a controlled burn was carried out in September 2000 in the lower 20% of the reserve. Paths were cut through the rest of the reserve to improve access for butterfly and food plant monitoring (Figure 5, on the left, shows one of these paths).

Subsequent observations proved the beneficial effect of these paths on the food plant and butterfly populations, and the unsustainability of burning as a management method. Current management strategy is based on path maintenance, selective removal of thicket species, and a zero tolerance alien control programme. Annual maintenance costs are currently less than R10 000, and are funded by the BBT.

The Brenton Blue Management committee, under project leader, Dr Annelise Vlok, produced an Environmental Management Plan for the BBBR in January 2001 (Schutte-Vlok 2001) (This document is currently under revision and will be made available online as soon as it is completed).

The land north of W K Grobler (see map, Figure 3 above) is public open space owned by the Greater Knysna Municipality (GKM), and the Management Committee has approached the GKM with a proposal to manage this land to create more habitat for the butterfly.

See which species are protected by the Brenton Blue reserve