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; H.G. Young in litt. 2003). It probably prefers marshy areas and shallow water (H.G. Young in litt. 2003). However, the site of its rediscovery is a volcanic lake with very little emergent vegetation (H.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 (H.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).

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, but died in captivity a year later (Bamford et al. 2015). Intensive searches (including major publicity campaigns) at Alaotra during 1989-1990 and 1993-1994 failed to discover more birds (Bamford et al. 2015). 

However, in 2006 the species was rediscovered when nine adults and four juveniles were observed at a volcanic lake situated 330 km north of L. Alaotra (S.T. Seing in litt. 2006, Rene de Roland et al. 2007). 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). The population is centred on L. Matsaborimena, one of four high altitude lakes near Bemanevika, but there is clearly some movement of individuals between these lakes. Lake Andriakanala regularly holds small numbers and in March/April more individuals may be present here than at Matsaborimena, while L. Matsaborimaitso occasionally holds up to five individuals (Bamford et al. 2015). No individuals have been seen on L. Maramaratsalegy (Bamford et al. 2015). The maximum area of occupancy (AOO) for the lakes used at this site is 16 km², however breeding has only been recorded from a small section of L. Matsaborimena, such that a minimum AOO related to breeding area would be only a single 2 km x 2 km square, 4 km². The extent of occurrence is similarly restricted, with a minimum convex polygon around the lakes used encompassing 25 km².

A second conservation population has been established at Lake Sofia through the release of birds reared in captivity from clutches taken from L. Matsaborimena (Gill 2009, Durrell.org 2020, H.G. Young in litt. 2020, BIAZA 2022). Releases began in December 2018 and the first breeding occurred in early 2020 (BIAZA 2022): this population is reliant on supplementary feeding in floating aviaries designed especially for the species (Bassett 2017) and currently numbers 47 mature individuals (BIAZA 2022). There are now two purpose-built captive-breeding centres in Antsohihy (H.G. Young in litt. 2020) which hold a captive population of more than 100 individuals (BIAZA 2022).

Conservation Actions Underway
Formal protection of the site at Bemanevika was achieved in 2015 with the creation of National Protected Area Bemanevika. Outcomes and actions are specifically identify to address threats, including the encroachment of rice growing and slash-and-burn. A permanent research camp has been established nearby by The Peregrine Fund, which, along with awareness raising among the local communities, provides protection against accidental or deliberate damage.
In 2009, 24 eggs were brought into captivity from Bemanevika by Durrell Wildlife Conservation Trust (Durrell) and the Wildfowl and Wetlands Trust (WWT) to guard against imminent extinction and create a source population for reintroduction (Jarrett 2010). A breeding centre has been built in the regional capital, Antsohihy. The birds first bred in 2011, and a captive population of around 100 birds has been established. A second facility, which houses around 20 birds, was built nearby in 2017 to allow the public to view the birds for engagement and education (H.G. Young in litt. 2020). An IUCN Species Action Plan (Woolaver et al. 2016), developed by a wide range of stakeholders, identifies conservation goals, objectives and actions. Analysis and surveys of wetlands by WWT and Durrell across the species’ presumed former range identified Lake Sofia as a release site (Cranswick et al. 2018). Following social and ecological surveys, work since 2014 with a development agency has sought to ensure appropriate management and sustainable livelihoods. The site was designated as a Ramsar site in 2017. A translocation plan to reintroduce the species to Lake Sofia (Cranswick et al. 2018) was approved by Government in 2018. Novel infrastructure was developed for the release of a diving duck including floating aviaries (Bassett 2017), and the first releases (21 birds) were in December 2018 (H.G. Young in litt. 2020). The first breeding took place in November 2019, with 8 chicks fledging in January 2020 (H.G. Young in litt. 2020, Anon. 2020). A further 35 individuals were released between September and November 2021 (H.G. Young in litt. 2022).
Lake Alaotra became a Ramsar Site in 2003. Efforts are underway to conserve the last vestiges of suitable habitat here (Morris and Hawkins 1998), but 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).

Conservation Actions Proposed
Continued close monitoring of the wild population is needed to track population trends and to detect potential declines rapidly. Ecological research of birds and habitat at Bemanevika and Lake Sofia (and elsewhere in the presumed former range), and post-release monitoring, will inform management of both sites. A habitat restoration plan for Lake Sofia is under development. Continue to monitor the wild population closely. Continue the captive-breeding programme, and supplement the population on Lake Sofia. Ecological monitoring is also required at Bemanevika.