At the same time, they reduced the diameter of the entrances to some of the nest boxes, in order to deny admission to cowbirds (which are larger than warblers).

ECONOMIST: How cowbirds run protection rackets

He said the drill diameter would be reduced from 28 inches to 26 inches until the hammer had cleared the hard rock but added that the slightly smaller diameter would not cause problems for the rescue.

CNN: STORY HIGHLIGHTS

Extrapolating from this result, Dr Mileikowsky thinks that in a meteorite with a diameter of 20cm it would take about 1m years for such a colony to be reduced to a millionth of its original size.

ECONOMIST: Panspermia: Interplanetary migration | The