Windhoek — Mile 4 has supported about 46 000 birds on average in recent years. Occasionally, Mile 4 Saltworks, one of Namibia's 21 Important Bird Areas (IBAs) supports massive numbers of water birds.
According to the latest Coastal/Marine Birds Namibia newsletter, the guano platform covering 31 000 square meters which was built in one of the northern pans has supported up to 700 000 Cape Cormorants in the past.
Apart from cormorants, the area supports more than 50 000 other waterbirds, including the greater flamingo and lesser flamingo, African black oystercatcher and up to 100 000 common tern.
Breeding species at Mile 4 include Damara tern, chestnutbanded plover, kelp gull, Hartlaub's gull and Caspian tern.
IBAs are sets of sites in various countries throughout the world that are considered to be critically important for birds on a global scale. The sites are selected according to criteria determined by BirdLife International and aim to protect bird species, bird sites and the wider environment.
Twelve of these IBAs are coastal or marine and include river mouths, wetlands, game reserves and national parks, plateaus, pans, mountains, lagoons, nature reserves and islands.
The area, comprising of a private nature reserve of 400 ha and a salt works, lies adjacent to the sea on the central Namib Desert coast and has been extensively altered to create numerous evaporation ponds.
In 1997, the area witnessed the first recorded attempt of greater and lesser flamingo breeding in coastal areas.
Just over 100 nests were built in the saltpan and eggs were laid, but presumed disturbance by blackbacked jackal led to early failure.
Recent breeding attempts on islands in the saltpans by cormorants and the occurrence and possible breeding of the near-endemic Gray's lark, immediately inland, add to the reserve's importance. Brown hyena is also found in the area.
The Richwater Oyster Company has been cultivating oysters in the pan since 1985. Oyster production and guano scraping appears to be compatible with maintaining good populations of wetland birds, judging by the large numbers present and the breeding of terns, cormorants and plovers in and around the salt works.