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Location Malawi, Southern
Central coordinates 35o 40.00' East  15o 15.00' South
IBA criteria A1, A4i, A4iii
Area 220,000 ha
Altitude 620 m
Year of IBA assessment 2001

Wildlife and Environmental Society of Malawi (WESM) (Affiliate)



Site description Lake Chilwa is a shallow lake (1.5–3 m, maximum 5 m) that drains an area of c.8,000 km² of hills and mountains; it is bordered on all sides by swamps and seasonally flooded grassland, especially extensive on the flat western and northern shores. The lake itself is c.700 km² in size (or more at maximum extent), but dries up occasionally after a series of dry years (as in 1968, 1973 and 1995). It is very rich in fish and supports a population of c.60,000 people. The swamp vegetation consists mainly of Typha (c.650 km²) and Phragmites reedbeds (150–300 km²), with extensive patches of Scirpus in the open lake, whereas flood-plain grassland covers c.400 km². Several large rice-growing areas have been developed in the swamp, and the edges are cultivated (under maize) in the dry season, covering an estimated 10% of the surface overall.

Key Biodiversity See Box for key species. There has been no systematic survey of the avifauna, but over 160 species of birds associated with the Chilwa wetlands have been identified so far. In periods of flood the area supports very high numbers of waterfowl, but the flat terrain, the enormous size of the swamp and the nature of the vegetation all make counting of even the larger waterbirds a nearly impossible task. Preliminary studies carried out in 1996 have shown that numbers of at least nine species of waterfowl exceed the 1% thresholds; for the four main species snared by trappers (Dendrocygna bicolor, Gallinula angulata, Porphyrula alleni and Amaurornis flavirostris) the latest survey of commercial hunting in 1998–1999 has revealed that over one million birds were taken in a few months. It is likely other species exceed thresholds, e.g. a combined total of 41,500 Anas hottentota and A. erythrorhyncha were snared and shot in 1998–1999, but the proportion of each is unknown. Of species of global conservation concern, Falco naumanni winters in some numbers (flocks of 25–30 at any one spot are not unusual) and the Chilwa flood-plain is certainly the most important site for this species in Malawi. Circus macrourus and Gallinago media both winter annually is small numbers while Phoenicopterus minor is only an occasional visitor. In general, much more fieldwork is needed, especially in seasonally flooded grassland, in order the verify the very high figures of crakes and other species reported by trappers. A ringing scheme aimed particularly at the migratory duck species would be useful in determining the origin of these seasonal populations.

Non-bird biodiversity: None known today; large mammals have been exterminated.

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
Fulvous Whistling-duck Dendrocygna bicolor winter  1999  100,000 individuals  A4i  Least Concern 
Glossy Ibis Plegadis falcinellus winter  1999  5,000 individuals  A4i  Least Concern 
African Spoonbill Platalea alba winter  1996  300 individuals  A4i  Least Concern 
Black Heron Egretta ardesiaca winter  1996  600 individuals  A4i  Least Concern 
Lesser Kestrel Falco naumanni winter  present  A1  Least Concern 
Pallid Harrier Circus macrourus winter  present  A1  Near Threatened 
Black Crake Zapornia flavirostra winter  1999  100,000 individuals  A4i  Least Concern 
Purple Swamphen Porphyrio porphyrio winter  1996  2,500 individuals  A4i  Least Concern 
Allen's Gallinule Porphyrio alleni winter  1999  200,000 individuals  A4i  Least Concern 
Lesser Moorhen Gallinula angulata winter  1999  600,000 individuals  A4i  Least Concern 
Great Snipe Gallinago media winter  uncommon  A1  Near Threatened 
Grey-headed Gull Larus cirrocephalus winter  1996  2,500 individuals  A4i  Least Concern 
African Skimmer Rynchops flavirostris winter  2000  280 individuals  A1, A4i  Near Threatened 
A4iii Species group - waterbirds winter  1999  1,000,000-2,499,999 individuals  unknown  A4iii   

IBA Monitoring

2001 high not assessed not assessed
unset
Good - based on reliable and complete / representative data

Over-exploitation, persecution and control of species hunting & collecting terrestrial animals - intentional use (species being assessed is the target) happening now majority/most of area/population (50-90%) moderate to rapid deterioration high

Protected areas

Protected area Designation Area (ha) Relationship with IBA Overlap with IBA (ha)  
Lake Chilwa Wetlands of International Importance (Ramsar) 224,800 protected area contains site 220,000  

Habitats

IUCN habitat Habitat detail Extent (% of site)
Artificial - terrestrial   14%
Wetlands (inland)   57%
Shrubland   12%
Forest   16%

Land use

Land-use Extent (% of site)
agriculture -
fisheries/aquaculture -
hunting -
nature conservation and research -

References Schulten and Harrison (1975), Wilson (1999), Wilson and van Zegeren (1998), van Zegeren and Wilson (1999).

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Recommended citation  BirdLife International (2014) Important Bird Areas factsheet: Lake Chilwa and flood-plain. Downloaded from http://www.birdlife.org on 26/12/2014

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