Madagascar pochard / Madagascar White-eyed duck

Aythya innota

Madagascar witoogeend / Madagaskar Moorente

This species was rediscovered in 2006 following the last sighting in 1991. It is currently known from a single location where 29 mature individuals were seen in 2011. While it may also persist at other sites, the population is likely to be tiny and therefore it is classified as Critically Endangered (IUCN, 2011).

A total of 25 adult birds were counted at the rediscovery site in 2008, with 29 there in 2011 (L.-A. Réne de Roland in litt. 2012). The species may persist elsewhere but the numbers are likely to be tiny, with fewer than 50 individuals and mature individuals.

Given that it has a tiny known population, it faces significant risk from stochastic events and genetic factors, particularly inbreeding depression. Since permanent guards have been positioned at the rediscovery site the population appears to have increased, suggesting that hunting may have been a threat there (L.A. Rene de Roland in litt. 2008), however breeding success has remained low, with no young reared in some years. Young may have trouble finding adequate food and if they do fledge likelihood of dispersing birds surviving away from main site is very low (H. G. Young in litt. 2012). Slash-and-burn agriculture takes place in the catchment around the sole remaining site, and may be causing ash and silt sedimentation which has left the majority of the lake in very poor condition with little suitable food (Cranswick 2012). Previous declines have been attributed to the widespread loss of habitat through siltation and conversion to agriculture throughout the central plateau and, from the 1950s, introduction of exotic fish species to Alaotra and other wetlands (Young and Kear 2006). Lake Alaotra, one of very few unconverted central plateau wetlands, is under considerable and increasing pressure: the area is one of Madagascar's major rice producers, with 250 km² of the 350 km² surrounding the lake converted to rice cultivation (Edhem 1993). Soil erosion from deforested hillsides and more intensive agricultural practices have diminished the water quality of the lake (Pidgeon 1996). Introductions of exotic plants, mammals (Rattus) and fish, especially Tilapia, have depleted essential food supplies and likely increased nest-predation for the species (Pidgeon 1996). The introduction of Tilapia into Alaotra probably had a devastating effect on the pochard and other more widespread waterbirds preferring emergent vegetation (G. Young in litt. 2003). Some of these species apparently died out at Alaotra but have repopulated from other parts of their ranges as water-lilies and other emergent vegetation have made a comeback along the marsh's southern edge (G. Young in litt. 2003). Hunting and trapping of adults for food, and death through entanglement in monofilament gill-nets, are thought to have contributed to the decline of this species (Morris and Hawkins 1998).

Conservation Actions Underway
The Peregrine Fund and Durrell Wildlife Conservation Trust are conducting further surveys at the site of rediscovery, which is currently permanently guarded, and are now seeking the support of locals to gain formal protection for the area (R. Watson in litt. 2006; L.A. Rene de Roland in litt. 2008; Watson 2007; Cranswick 2010). Furthermore, together with the Wildfowl and Wetlands Trust and the government of Madagascar, and with support from with Mitsubishi Corporation Fund for Europe and Africa, a conservation breeding facility has been built, and a Malagasy warden was to be appointed to help protect the breeding site (Anon 2009). A small number of eggs were opportunistically taken from the wild in 2009, leading to hatching of the first captively-reared individuals(Jarrett 2010), with three clutches successfully hatched by the end of the year, producing 20 young (Cranswick 2010). The long-term aims of such efforts are to secure of the existing population and to establish another viable population in the wild (Cranswick 2010). Work is ongoing through WWT, the Peregrine Fund and two PhD students to identify potential areas for the release of captive-bred birds, which will probably necessitate some habitat restoration (Cranswick 2010, 2012). Efforts are underway to conserve the last vestiges of suitable habitat at Lake Alaotra (Morris and Hawkins 1998). The Malagasy government has ratified the Ramsar Convention, and Lake Alaotra became a Ramsar Site in 2003. Searches for the species continue, as do education and awareness programmes on the benefits of maintaining natural wetlands. However, implementation of any conservation policy for the area will be very difficult owing to Alaotra's huge economic importance for agriculture and fisheries (Pidgeon 1996).

Above: four species of white-eyed pochards. Click the image to enlarge. 

Conservation Actions Proposed
Continue searches for extant populations, with a particular focus around former high-plateau wetlands (Rene de Roland et al. 2007). Protect areas of least-modified wetland at Lake Alaotra. Continue community surveys and wetland awareness programmes. Conduct further surveys to determine the existing population size. Continue work to establish a captive-breeding programme. Carry out inventory of wetlands near remaining population to identify sites for release of captive-bred birds and assess the need for habitat restoration (Cranswick 2010).

More information: http://www.iucnredlist.org/details/100600477/0

http://www.wwt.org.uk/conservation/wwt-projects/saving-the-madgascar-pochard/