More dead birds fall from sky in US
Test are being carried out on about 500 red-winged blackbirds and starlings found dead in the US state of Louisiana.
It happened just a few days after some 3,000 blackbirds fell to Earth in neighbouring Arkansas in the small town of Beebe.
Several scientific explanations as well as conspiracy theories have been put forward to explain what may have happened.
Iain Mackenzie reports from Washington.
05 Jan 2011