Justification of Red List Category
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 and 21 in 2012. While it may also persist at other sites, the population is likely to be tiny and therefore it is classified as Critically Endangered.
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) and 21 in 2012 (Bamford et al. 2015). The species may persist elsewhere but the numbers are likely to be tiny, with fewer than 50 individuals and mature individuals.
The species is likely to have dramatically declined in the past. Recent surveys suggest a modest increase in the tiny population which may be aided by conservation efforts. However, the population is still extremely small and prone to stochastic events. Breeding success is very limited with no young reared in some years. Young may have trouble finding adequate food and if they do fledge the likelihood of dispersing birds surviving away from main site is very low (H. G. Young in litt. 2012).
This species is endemic to Madagascar (although sub-fossil remains of an Aythya duck on Reunion are attributed to A. innotata), where it was found historically in the Lake Alaotra basin in the northern central plateau. It was considered relatively common at Lake Alaotra in the 1930s, but declined dramatically through the 1940s and 1950s (Young and Kear 2006, Rene de Roland et al. 2007). Until the 1990s, the last certain record was at Lake Alaotra in 1960, with one unconfirmed sighting near Antananarivo in 1970 and several other possible records. Then a single male was captured alive in August 1991. Intensive searches (including major publicity campaigns) at Alaotra during 1989-1990 and 1993-1994 failed to discover more birds. However, in 2006 the species was rediscovered when nine adults and four juveniles were observed at a volcanic lake situated 330 km north of Lake Alaotra (S.T. Seing in litt. 2006). Reports from local people that the lake was not suitable for rice cultivation round the edge, it contained no fish and that the water was cold suggest that the species may have persisted at this new location because human disturbance has been minimal (S.T. Seing in litt. 2006). Follow-up surveys in 2006 located c.20 mature individuals with up to nine ducklings observed at the same site (G. Young in litt. 2007). Five birds were seen at a second lake c.3-4 km from the site but these may be part of the 20 individuals counted previously. A total of 25 mature individuals were counted in 2008, with six pairs nesting in the 2007/08 season (L.-A. Rene de Roland in litt. 2008). However, no chicks fledged in 2008 or 2009 (P. Cranswick in litt. 2009, H. G. Young in litt. 2012), and only 19 adults were recorded in July 2009 (Jarrett 2010), including six females (Cranswick 2010). In 2011 there was again no successful breeding, and the lake was apparently in poor condition with little available food other than caddis fly larvae (Cranswick 2012), however a total of 29 mature individuals were counted (L.-A. Rene de Roland in litt. 2012). In 2012 a total of 21 individuals were counted (nine females and 13 males) and 20 breeding attempts were recorded (Bamford et al. 2015).
Behaviour This species is generally sedentary and usually occurs singly, or occasionally in pairs (Young 2011). It is not known to flock or to associate with any other species (Kear 2005). Nesting has been observed during the months of July to February (Bamford et al. 2015). Some pairs may make multiple nesting attempts (Bamford et al. 2015). Habitat The species was historically only known from shallow freshwater lakes and marshes that combine open water with nearby areas of dense vegetation (Langrand 1990; Morris and Hawkins 1998; G. Young in litt. 2003). It probably prefers marshy areas and shallow water (G. Young in litt. 2003). However, the site of its rediscovery is a volcanic lake with very little emergent vegetation (G. Young in litt. 2007). What vegetation does grow at the lake edge may provide suitable nesting habitat. The requirement for shallow water may prevent it from using other volcanic lakes similar to the site of its rediscovery (G. Young in litt. 2007).The nest is sited amongst lake-edge vegetation (Cyperaceae) and placed 20-40 cm above water (Bamford et al. 2015). The clutch size is 6-10 eggs (Young 2011). Diet It is believed to feed almost entirely on invertebrates with a minimal proportion of plant matter (Bamford et al. 2015).
Given that it has a tiny known population, it faces significant risk from stochastic events and genetic factors, particularly inbreeding depression. Hunting may have been a threat at the rediscovery site and permanent guards have been positioned there (L.A. Rene de Roland in litt. 2008), however breeding success has remained low, with no young reared in some years, and there has been no particular increase in population (G. Young in litt. 2016). Overall fledging success was 1.8% in 2011 and 6% in 2012 (Bamford et al. 2015). Young may have trouble finding adequate food at the rediscovery site as the lake is too deep for young birds to dive and has a low density of invertebrates (Bamford et al. 2015), and Nile crocodile in the lake may predate the species (R. Thorstrom in litt. 2016). If they do fledge, likelihood of dispersing birds surviving away from the 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 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), or its failure to re-colonise loactions (G. Young in litt. 2016). Climate change may have future implications for this species, including indirect implications as a result of impacts on human populations (Segan et al. 2015).
Conservation Actions Underway
The Peregrine Fund, Durrell Wildlife Conservation Trust and the Wildfowl and Wetlands Trust are conducting further surveys at the site of rediscovery, which is currently permanently guarded. Formal protection of the area was achieved in 2015 with the creation of NAP Bemanevika (G. Young in litt. 2016). Durrell together with the Wildfowl and Wetlands Trust and the government of Madagascar, and with support from the Darwin Initiative, Mitsubishi Corporation Fund for Europe and Africa, and others, established a conservation breeding facility, and a Malagasy warden was appointed to help protect the breeding site (G. Young in litt. 2016). Twenty four eggs were opportunistically taken from wild in 2009, leading to hatching of the first captively-reared individuals (Jarrett 2010). The first captive-bred chick hatched in 2011, and 63 hatched by March 2015 (G. Young in litt. 2016). The long-term aims of such efforts are to secure the existing population and to establish another viable population in the wild (Cranswick 2010). Work was undertaken by WWT, Durrell 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); and, with Lake Sofia identified as a potential site for the release of captive-bred birds, the Darwin Initiative project: Establishing Sustainable Management of the Lake Sofia Catchment Madagascar was started in 2015 (G. Young in litt. 2016). 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). A Species Action Planning workshop for the species was scheduled for December 2013 (G. Young in litt. 2013), with a Species Action Plan published in 2015 (Woolaver et al. 2015).
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. Continue to monitor the wild population closely. Continue the captive-breeding programme, and there are aims to open a second establishment (G. Youn in litt. 2016). 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). Lake Sofia has potential as a release site however further research and ecological monitoring is needed to establish its suitability (Cranswick 2014); and ecological monitoring is also required at the wild site for this species. Install floating rafts for nesting and for placing supplementary food at sites where the species is currently found (Bamford et al. 2015).
45-56 cm. A medium-sized diving duck. Male is dark mahogany-brown all over except for white eye, white undertail-coverts, white underparts and conspicuous white wing-bar along bases of flight feathers. Bill is dull brown with paler, bluish subterminal band. Female is duller brownish, lacking white eye. Similar spp. From all waterfowl by overall dark plumage and white undertail-coverts and wing-bar extending length of the wing. In addition, from White-backed Duck Thalassornis leuconotus by uniform colouration, dark back and white eye (in male), from Red-knobbed Coot Fulica cristata by mostly dark bill, and from all other ducks by diving habit and running take-off. Hints Rather tame.
Text account compilers
Benstead, P., Bird, J., Butchart, S., Calvert, R., Ekstrom, J., Evans, M., Shutes, S., Symes, A., Taylor, J., Martin, R, Ashpole, J & Westrip, J.
Hawkins, F., Rabenandrasana, M., Réné De Roland, L., Seing, S., Watson, R., Young, G. & Thorstrom, R.
BirdLife International (2019) Species factsheet: Aythya innotata. Downloaded from http://www.birdlife.org on 25/08/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 25/08/2019.