A study of the world’s rarest bird – the Madagascar pochard – has revealed that 96 per cent of the chicks die before fledging.
The conclusion reached by researchers from the Wildfowl and Wetlands Trust (WWT) is that the last remaining population will never expand without outside help.
Just 25 pochards remain in the wild, restricted to one wetland in northeast Madagascar – a complex of lakes near Bemanevika.
The study, published in Bird Conservation International, found that the level of mortality actually increases as the chicks get older, peaking when they are between two and three weeks old.
The researchers conclude that most chicks slowly starve to death once they’re old enough to dive for food, because the water in the lakes is too deep for them.
Historically, it is unlikely that the pochards bred at Bemanevika, but they have been forced from their favoured habitats as wetlands across Madagascar have been turned over to rice and fish farming. The lake’s remoteness has allowed them to survive undisturbed.
The volcanic lakes that are the last refuge of the few remaining wild Madagascar pochards
The wetlands that had formed in volcanic craters are deep with steep sides and surveys showed that, even in the sediment, little food is available to the ducks. Researchers found that ducklings fed at the surface until they were two weeks old, which is typically when related species switch to diving for food. The elevated levels of mortality were observed after this point.