Lake Chilwa Wetland: The world’s bird migratory dreamland
Lilongwe – Situated in Malawi’s southern region, the 230 000 ha Lake Chilwa Wetland lies north of the Phalombe plain between the imposing, picturesque Zomba and Mulanje mountains.
Its main harbour, Kachulu, is only 30 km from the nearest city, Zomba.
Lake Chilwa Wetland comprises an inland water body with several inflowing rivers and is surrounded by swamps, marshes and floodplains in an area stretching about 40 km across from east to west and 60 km from north to south. The recorded plant biomass production of the predominant lake habitat of Typha and Phragmites reeds registers as much as 20-30 tonnes per hectare per year.
Water in the wetland is only lost through evaporation, transpiration and seepage, and the remainder is what forms Lake Chilwa.
The size of the lake largely depends on precipitation in the catchment, with a small increase in water level resulting in a tremendous increase in surface area while a decline steadily shrinks it.
Since the maximum depth of the lake is less than 5m, wind action keeps the water column variable.
The lake and its wetland is an important bayou for water birds, providing breeding, resting and feeding areas for flocks of birds in the one of the world’s famed flyway ‑ the West Asian-East African Flyway.
The Malawian bird dreamland is mostly favoured for its river mouths that provide a safe haven for breeding, as these areas are largely inaccessible to people and offer protection to the birds because of the dense marsh vegetation.
The Lake Chilwa Wetland, designated as a wetland of international importance (World Ramsar Site No. 869) in 1997, is said to support 1.5 million residents, seasonal and migratory water bird populations and qualified as an international site because the number of waterfowl population supported by the wetland far exceeded the 20 000 waterfowl Ramsar criteria.
The wetland was also proposed for a biosphere reserve. Lake Chilwa which has widely been used for fishing by the local communities has however, become a bird hunting ground to supplement food consumption and income during dry spells.
It is estimated that about 1.2 million birds are trapped annually by at least 460 trappers, with an annual economic value estimated at US$215 000.
Species trapped in large numbers include Common Moorhen Gallinula chloropus, Lesser Moorhen, Allen’s Gallinule, Blake Crake, Fulvous Whistling-Duck, White-faced Whistling-Duck Dendrocygna viduata and Hottentot Teal Anas hottentota
According to Birdlife International, one of wetland-dependent bird species of global concern which occurs regularly in significant numbers in the Chilwa wetlands is the African skimmer (Rynchops flavirostris).
The wetland also holds populations of the vulnerable lesser kestrel (Falco naumanii), the locally rare pallid harrier (Circus macrourus) and great snipe (Gallinapo media).
The Wildlife and Environmental Society of Malawi (WESM) opines over 160 species of birds including migratory duck species have been identified to associate with the Chilwa wetlands.
Studies also show that at least nine species of waterfowl including Dendrocygna bicolor, Gallinula angulata, Porphyrula alleni and Amaurornis flavirostris are snared by trappers.
A survey on commercial hunting has revealed that species of global conservation concern such as the Falco naumanni find the Chilwa flood-plain a most important site for this species in Malawi.
It is believed that snaring and shooting of birds have been practised for a long time, but commercial exploitation of waterfowl started on a large scale in 1996, following the drying up of the lake and collapse of fishery in 1995.
It was then estimated that over 356 000 waterfowl were trapped on the western shores. However, despite the recovery of the fishery industry, commercial waterfowl trapping has remained at a very high level. Hunted birds include several legally protected species such as pelicans, flamingoes, spoonbills, ibises and storks. Several large waterbirds have already been eliminated through hunting (e.g. both species of cranes) and others are clearly decreasing.
Other wetlands outside Malawi similar to Lake Chilwa are “iSimangaliso Wetland Park” formerly St Lucia Wetlands of South Africa and Area of Colchis wetlands and forests of Georgia both of which are also Ramsar sites.
Whereas iSimangaliso has over 500 different species of marine, wetland and forest birds resident that pass through the wetland system annually, the park is unique due to its having one of the most diverse variety of frogs and their choruses can often be heard at night and on dull rainy days.
The Area of Colchis wetlands and forests is one of the last remains of the landscape belt, rich in tropical and sub-tropical habitats, which existed some ten million years ago and stretches as an almost unbroken line over the vast Eurasian continent. It is unique because of its biodiversity, wetlands and forest ecosystems variety, high endemism, richness in relics of the tertiary period and especial objects of geological and paleontological importance.