Open image gallery
The regional population of the exquisite African Pygmy Goose Nettapus auritus is suspected to be in decline and surpassing the 30% threshold for qualification as regionally Vulnerable.
The African Pygmy Goose has a wide, albeit fragmented, distribution across sub-Saharan Africa and Madagascar (Scott and Rose 1996). Within southern Africa it occurs in Mozambique, Zimbabwe, Namibia and Botswana where the Okavango Delta forms the regional stronghold (Maclean 1997). In Zimbabwe the species occurs on the larger pan systems but is absent from the Zambezi Valley (Irwin 1981).
Within the region it is an uncommon visitor to eastern Swaziland (Parker 1994) although it is relatively common in neighbouring southern Mozambique (Cizek 2008). It is uncommon in north-eastern South Africa with the only permanent populations (given sufficient rainfall) occurring on the Nyl River Floodplain and in Kruger National Park. It is more numerous in KwaZulu-Natal, and can be locally common in the extensive wetland, floodplain and pan systems of Maputaland. In some subtropical areas pygmy geese are mainly sedentary, but elsewhere they are subject to dispersive movements dictated by habitat and water availability during the dry season (Carboneras and Kirwan 2014). The regional EoO has decreased only slightly since SABAP1 (now 383 681 km2) but the regional AoO has decreased by an alarming 47% to only 23 240 km2. Furthermore, only c. 2% of the reported AoO constitutes suitable habitat, meaning that a regional AoO of just 479 km2 is more realistic. The species occurs regularly in 12 IBAs, with sites such as with Kruger National Park (SA002), the Kosi Bay System (SA053), Mkuze Game Reserve (SA057) and iSimangaliso Wetland Park (SA058) being exceptionally important. Additional sites where large numbers have been recorded include Lake Mfutululu, Banzi Pan and Thulazihleka Pan in KwaZulu-Natal (Taylor 1999).
Unfortunately Barnes (2000) does not provide an estimate of the regional population although Carboneras and Kirwan (2014) make mention that flocks of c. 1 000 birds were recorded in northern Zululand during the dry season. The regional population in all likelihood fluctuates greatly in response to rainfall and the availaibility of pans in north-eastern KwaZulu-Natal. The regional population is in all likelihood less than 2 500 mature individuals; the confidence in this regional population estimate is low and requires verification.
Although some populations have unknown trends, the overall global population is decreasing (Dodman and Diagana 2006). The African Pygmy Goose is a distinctive and fairly conspicuous species and the c. 47% decline in AoO between reporting periods is a reasonable indication of a concomitant decline in the regional population over a three-generation period. The confidence in this estimate is medium.
The threats facing African Pygmy Geese are not dissimilar to those relevant to Lesser Jacanas Microparra capensis, which have similar habitat requirements. Major threats include wetland degradation and destruction and interference with floodplain ecology, particularly through impoundments such as Pongolapoort Dam. Siltation of rivers is of concern (Macdonald and Birkenstock 1980). Climate change may constitute the largest threat, with parts of north-eastern KwaZulu-Natal experiencing a decline in rainfall of greater than 50% over a fifteen year period, which has an adverse effect on habitat availability. Invasive alien species such as water hyacinth Eichhornia crassipes may decrease the amount of available habitat (Dowsett-Lemaire and Dowsett 2006). Kear (2005) speculated that predation by snakes may limit dry-land nesting; however, natural predation must be seen as a lesser threat.
There are no species-specific measures in place. The establishment of the 332 000 ha iSimangaliso Wetland Park in 1999 and, in particular, the removal of plantations from both the Western Shores and Eastern Shores sections of the park, has probably greatly benefited this species.
The conservation of the African Pygmy Goose in the region depends chiefly on the protection of wetlands, floodplain systems and pans in north-eastern KwaZulu-Natal and the species should be included in future conservation planning initiatives. Control of invasive alien plant species would be beneficial. A practical measure would be to provide suitable nest boxes to encourage breeding at some wetland sites.
* The threats facing the species should be evaluated before targeted conservation actions are put in place.
* Regular monitoring of the regional population and sub-populations at key sites is recommended.