Avian Demography Unit
Department of Statistical Sciences
University of Cape Town
ADU home     UCT Home page

Strandfontein Sewage Works
(Cape Flats Waste Water Treatment Works)

Site code: 34051831

Current compiler: Dick Barnes (Cape Bird Club)

  Photo © Rene Navarro
Aerial view looking south over the works showing the central and southern ponds, with False Bay in the background.
Map Strandfontein map
Map of Strandfontein Sewage Works showing the location of the site and the layout of the ponds. Modified from "Birds of the southwestern Cape and where to watch them" (Mondi Southern Birds 20)
Description Strandfontein Sewage Works is approximately 380ha in size and is situated on the north coast of False Bay. Zeekoeivlei and Rondevlei are located just to the north of the works.

Once a naturally occurring vlei, the area was converted into a series of settling and oxidation ponds when the sewage works was developed. It is part of the propsed False Bay Park which is a designated Important Bird Area (IBA, SA116) and is controlled and managed by the City of Cape Town.
Ecology

The works comprises 319ha of aquatic habitats and 58ha of terrestrial habitats. Five major aquatic habitats are recognised: permanent open ponds, seasonal open ponds, canals with aquatic vegetation (mainly Typha, Phragmites and Scirpus spp.) reedbeds and sludgebeds (Kaletja-Summers et al. 2001*). The verges between ponds are grassed while some of the ponds have sandy islands. The terrestrial sections of the works comprises stands of exotic Acacia cyclops (Rooikrans), grassland, dune vegetation and portions of strandveld.

* Kaletja-Summers, B., McCarthy, M. & Underhill, L.G. 2001. Long-term trends, seasonal abundance and energy consumption of waterbirds at Strandfontein, Western Cape, South Africa, 1953-1993. Ostrich 72(1&2): 80-95

CWAC history The works have been one of the Cape Bird Club's monitoring projects since the 1950s, but regular counts only started in July 1983 and have continued monthly since then (with only a few counts being missed due to extreme weather conditions!). Mike McCarthy coordinated the counts for 17 years before handing over to Dick Barnes in August 1999. Members of the Cape and Tygerberg Bird Clubs assist in the counting of the site.
Waterbird highlights

Strandfontein is rated as one of the top three waterbird sites in the southwestern Cape, and as one of the top five sites in South Africa (Kaletja-Summers et al. 2001).

Data from CWAC (1992-2000) show that the works can support up to 72 different waterbird species and 30 000 individuals. The latter figure is an extreme upper limit however, with counts usually averaging 15 000 birds during summer and 8 000 during winter. This huge variation in overall abundance is entirely dependent on the number of Cape Cormorants using the site as a post-feeding roost, which can number anything from a handful of birds to 15 000, the latter sometimes representing half of the total count! Counts from 1980-1990 showed that waterbird numbers averaged above 20 000 individuals, suggesting that numbers may have decreased slightly since the 1980s.

The site is important for numerous species, whose numbers regularly or occasionally reach global (1%) and/or regional (0.5%) population thresholds. The CWAC Report page for this site, accessed via Count data below, gives an indication of those species that fall into these categories.

In addition, the site supports one of the largest known populations of Glossy Ibis (up to 310 birds) and Maccoa Duck (up to 300 birds) in the Western Cape, the latter also ranking as the largest concentration of this species in South Africa after the Wilderness Lakes (CWAC data).

Strandfontein is also regular host to a number of Palearctic species such as Greenshank, Little Stint, Curlew Sandpiper, Ringed Plover and, in late summer, impressive flocks (up to 300 birds) of Whitewinged Tern. The following have also been recorded as vagrants: Knot, Whiterumped Sandpiper*, Pectoral Sandpiper*, Franklin's Gull*, Blackheaded Gull*, Blacktailed Godwit*, Grey Plover, Rednecked Phalarope and Yellow Wagtail.

* denotes National Rarity  (a full list of National Rarities is available at Zest for Birds)

Count data
Click on the icon to view this site's page in the TOTAL CWAC report (pdf format).

This page summarises CWAC counts for Strandfontein Sewage Works from 1993-1997.

Please note: mean and maximum counts for species are marked with asterisks where they reach certain thresholds: ** = 1% of the estimated global population and * = 0.5% of the estimated global population.
   
Breeding records Confirmed
  • Great Crested Grebe
  • Dabchick
  • Whitebreasted Cormorants - known to have bred on the island in S3
  • Sacred Ibis - colony of about 100 pairs in 2001
  • Egyptian Goose
  • Cape Teal
  • Southern Pochard
  • Maccoa Duck
  • Yellowbilled Duck
  • Redknobbed Coot
  • Purple Gallinule
  • African Black Oystercatcher - min. 1 pair
  • Blacksmith Plover
  • Kittlitz's Plover
  • Water Dikkop
  • Blackwinged Stilt
  • Kelp Gull
  • Hartlaub's Gull
  • LeVaillants Cisticola
  • African Sedge Warbler
  • Cape Reed Warbler


  • Suspected
  • Redbilled Teal
  • Cape Shoveller
  • Moorhen
  • Threatened waterbirds
    Barnes 2000
    The following Red Data species have been recorded at the works:

    Vulnerable:
  • Bank Cormorant
  • African Marsh Harrier


  • Near-threatened:
  • Great White Pelican
  • Cape Cormorant
  • Greater Flamingo
  • Lesser Flamingo
  • African Black Oystercatcher
  • Chestnutbanded Plover
  • Caspian Tern
  • Other birding highlights The works has an overall species list of 195 and includes southern African endemics such as Bank Cormorant, Cape Cormorant, Cape Shoveller, African Black Oystercatcher, Hartlaub's Gull, Cape Francolin, Greywing Francolin, Cape Bulbul, Spotted Prinia, Bokmakierie and Cape Weaver.

    Conservation issues

    Although not formally protected, the site is unique in that it plays an important role as a refuge and/or breeding site for many waterbirds all within the boundaries of an active waste water treatment plant.

    The development of a proposed multi-lane tolled motorway linking the M3 with the R300 is a major cause for concern, as it will run through the northern section of the works and along the southern boundary of Zeekoeivlei.

    Anyone wanting to voice their objection should contact Emily Herschell of Chand Ecosense (Tel: 021-418 4212) and register as an Interested & Affected Party (I&AP). Further information can also be obtained from Nicki Stock of the Zeekoevlei Environmental Forum - Tel: (021) 705-3587.

    Additional detailed information about the motorway development and maps showing the proposed route of the toll-road are available from the Zandvlei Trust website.

    Photo gallery

     
    Ponds S8 (left) and S3 (right) usually hold the greatest concentration of Greater Flamingos. Photos © Doug Harebottle

     
    Sunset over Pond P4 (left) and aerial view looking west over the central ponds towards Muizenberg (right). Photos © Rene Navarro and Les Underhill


    Back   ADU Home page
    Office Avian Demography Unit
    Enquiries/More Information: adu-info@uct.ac.za
    Last updated 14 August 2002