Health officials in Massachusetts are trying to figure out what caused a large flock of birds to fall out of the sky and on to a Boston street.

NECN reported that 47 songbirds were found in the city's Dorchester neighbourhood. Some of the grackles were found dead, while others were just sick.

The Animal Rescue League of Boston says it went to the neighbourhood after residents reported birds falling from the sky and a sick cat. The cat was later euthanised.

The birds that died will be sent to Tufts University for testing.