At the northern end of the lake system, the estuary opens into the sea providing a relatively large area of open sandbanks, mudflats and some of the most diverse and extensive mangrove swamps anywhere in South Africa. The attraction of Kosi is not restricted to the aquatic environment, given the extensive surrounding tropical East Coast littoral vegetation including mature coastal forest, thicket and grassland. The fringes of the lakes and, in particular, the southern lakes hold relatively large areas of swamp and Raphia Palm Forests. Within this vegetation mosaic a number of endemic species as well as species at the southern end of their Afrotropical range can be found.

The summer months are best for waders, and the estuary attracts a good diversity of species including the usual Common Greenshank, Curlew Sandpiper and relatively large numbers of Eurasian Whimbrel, Eurasian Curlew, and Bar-tailed Godwit amongst others. Small numbers of Greater and Lesser Sand Plovers are also present at times and, if one is lucky, the odd Crab-plover may reveal itself from the mangroves. Other birds include the Black and Rufous-bellied Herons, an assortment of terns including the Little and Lesser Crested Terns, Giant Kingfisher, both Greater and Lesser Flamingos, and Saddle-billed Stork. This is also one of the most reliable sites in South Africa for the range-restricted Mangrove Kingfisher, which is best detected by its loud and distinctive call.

The lakes themselves are best explored by boat. African Fish Eagle, Western Osprey and Palmnut Vulture are all common and can be seen patrolling the shoreline or lakeside fringes, while reedy channels holds small numbers of Rufous-winged Cisticola, African Sedge and African Reed Warblers and ever present African Marsh Harriers. Quiet backwaters attract Malachite Kingfisher, African Pygmy Geese and White-backed Duck. The ‘narrows’ trip can be sometimes be arranged at night, where sightings of Pel’s Fishing Owl are regular.

The coastal forest support a plethora of interesting species including the Common Square-tailed Drongo, Black-bellied Starling, Woodwards’ Batis, Narina Trogon, Green Malkoha, African Broadbill, Yellow-streaked Bulbul, Grey Cuckooshrike, Yellow-rumped Tinkerbird, Chorister and Red-capped Robin-chats, Olive and Gorgeous Bush-shrikes, Blue-mantled Crested Flycatcher, both Rudd’s and Yellow-breasted Apalis, Eastern Nicator, Terrestrial Brownbul, Yellow-bellied Greenbul, Trumpeter Hornbill, Livingstone’s Turaco, and the Spectacled and Dark-backed Weavers. Overhead, watch for the African Cuckoo-hawk and Southern Banded Snake-eagle – both species are regularly seen hunting along the forest edge. The incredibly range-restricted Plain-backed Sunbird is also occasionally sighted. The Raphia Forests support relatively large numbers of Palmnut Vulture; this being one of the most reliable sites for the species anywhere within southern Africa. A canoe trip into the swamp forest up the Siyadla River at the southern end of the fourth lake regularly produces African Finfoot, Western Osprey, African Pygmy Geese, Southern Brown-throated Weaver, and Purple Heron.

The larger patches of grassland within the woodland mosaic support Black-bellied Bustard, both the Flappet and Rufous-naped Larks, Croaking Cisticola, European Roller (summer), Shelley’s Francolin and African Stonechat in winter. Moist grasslands and swamp to the south and west of Kosi Bay hold all three Longclaw species (Cape, Yellow-throated and Rosy-throated), Lesser Jacana, Blue-billed Teal, as well as a variety of typical moist grassland species including Pale-crowned Cisticola, and the African Wattled, Senegal and Black-winged Lapwings.

Key species:

Pink-throated and Green Twinspots, Palmnut Vulture, African Cuckoo-hawk, Gorgeous Bush-shrike, Crab-plover, Mangrove Kingfisher