* Blue stain believed to be sign of poisoning or hypoxia - lack of oxygen that is precursor to altitude sickness
* Cold weather and overbreeding blamed for deaths of two 2million fish in Chesapeake Bay
* Disease behind deaths of 100,000 fish in Arkansas River
* At least nine incidents of mass animal deaths across the globe
* Hundreds of confused birds plummeted to their deaths in multiple locations in the U.S.
* Rapid movement of Magnetic North Pole towards Russia may have caused bird deaths
Thousands of dead turtle doves rained down on roofs and cars in an Italian town in the latest in a growing spate of mass animal deaths across the globe.
Residents in Faenza described the birds falling to the ground like 'little Christmas balls' with strange blue stains on their beaks.
Initial tests on up to 8,000 of the doves indicated that the blue stain could have been caused by poisoning or hypoxia.
A witness told www.examiner.com: 'We have no idea why this happened all of a sudden.
'The doves just started falling one-by-one then in groups of 10s and 20s.'
Hypoxia, a lack of oxygen, is known to cause confusion and illness in animals. It is also a common precursor to altitude sickness.
Experts said results from tests on the doves will not be available for at least a week.
They said that cold weather could have caused the birds' deaths as the flock was swept into a high-altitude wind storm before falling to the earth.
It comes after two million dead fish were found to have washed up on shores in Chesapeake Bay, Maryland.
The alarming find is being blamed by authorities in Maryland on the stress caused by unusually cold water and overbreeding among spot fish.
via Animal death mystery: Two MILLION dead fish wash up in Maryland bay | Mail Online.