This is the time of the hawthorn blossom - may. Held as sacred by the ancients and still shown great respect by country folk. It is considered unlucky to chop a tree down or to bring cuttings into the the house.
In the Celtic tongue it is uath and takes sixth place in the ogham cycle (covering the period May 13th - June 9th). The bird associated with the sixth ogham month is the night-crow. However, none of the birds of the crow family fly at night so night-crow is either a creature of folk-lore or a nickname for a nocturnal species.
The answer to the above lies in the myth of the Wild Hunt, the ghostly procession of spirits, faeries, spectral hounds and witches which is believed to hunt the night sky. Led by the local god of the dead, Herne the Hunter, King Arthur, Bran or Odin. In Denmark the outrider for the Wild Hunt was the night- raven. Both Bran and Odin are associated with ravens and it was the cry of this bird heard at night which was believed to presage a passing to the Otherworld.