The world’s rarest bird, the Madagascan pochard (Aythya innotata), still relatively common at Lake Alaotra in Madagascar in the 1920s, was thought to be extinct in the late 1990s. The decline of this diving duck probably started some 60 years ago with the introduction of some fish species in the lake that killed most of the pochard chicks and damaged nesting sites. Rice cultivation, cattle grazing on the shores, burning of shore vegetation, introduced rats, gill-net fishing and indiscriminate hunting were factors that led to its disappearance. In 1960 a small flock of about 20 birds constituted the last record of multiple birds at Lake Alaotra, and in 1991 a single male was captured and kept in the Antananarivo Botanical Gardens until its death one year. Intensive searches and publicity campaigns in 1989-1990, 1993-1994 and 2000-2001 failed to produce any more records of this bird.
In November 2006 a flock of nine adults and four recently hatched ducklings were rediscovered at Lake Matsaborimena (or Red Lake) in a remote area of northern Madagascar. In 2008 only 25 adult birds had been counted in the wild.
In 2009, a rescue plan involving the Durrell Wildlife Conservation Trust and the Wildfowl and Wetlands Trust removed a batch of 24 ready-to-hatch eggs from nests and incubated them in a lab that was set up in a shore-side tent. After hatching, the day-old chicks were taken to a holding facility in a local hotel. Reared in captivity, they hatched eighteen ducklings in April 2012 at the captive breeding center in Antsohihy, bringing the total population to 60. In April 2013, the population reached 80. But the Madagascar pochard will not be able to thrive without a new wetland home.
A new study by experts of the Wildfowl and Wetlands Trust (WWT) established that 96% of the newly hatched chicks were disappearing at two to three weeks old. WWT researchers, estimate that only 25 individual birds now remain in one wetland in north-east Madagascar – a complex of lakes near Bemanevika. Piecing the evidence together, including samples of food from the bottom of the lake, the researchers realized that the chicks were starving to death.
These diving ducks feed from the bottom of lakes, and apparently the steep volcanic crater lake is simply too deep for them. But the researchers say the species could thrive in Madagascar again if the captive-bred ducks can be found a new wetland reintroduction site for the captive breeding population free from the pressures of fishing invasive predators.
More information at: http://www.wwt.org.uk/conservation/wwt-projects/saving-the-madgascar-pochard/
Author: Gerhard Damm