The shepherds mentioned in Luke chapter 2 are watching their flocks at night when angels appear to them on the hills to say that a Saviour has been born. The angels encourage the shepherds to go and find the new born baby; as a sign they will find him lying in a manger.
At this time, sheep were only pastured out on the hills all night in the warmer months of the year between March and November. Between December and February it was too cold for the sheep to be outside at night, so they were kept inside after dark in barns.
“And there were shepherds living out in the fields near by, keeping watch over their flocks at night. An angel of the Lord appeared to them, and the glory of the Lord shone around them, and they were terrified.” (Luke 2:8-9)
That the Christmas story includes shepherds watching their sheep out on the hills at night shows that the time of year could have been March or April, but not December. Thus, shepherds tending sheep out on the hills favours the Passover time of year for Jesus’ birth.
The shepherds descended to Bethlehem from the hills above the town, with sheep and lambs and found the baby hidden in the feeding receptacle beneath the hay. It was probably the sheep that found him there when they went to feed on the hay. Mary would have hidden the baby there in fear of the unknown visitors, I think, as no one used cradles for new-born babies back in those days.
Merry and True 