When are the lambs due?...... ancient wisdom or baloney?

 We know when they are due.... five months after mating and five days back. The tup went in on 5 th November and we should see the first lamb on 1st April.

Essential kit for ancient shepherds

But how did shepherds know this before there were calendars? Knowing when the lambs were due would be a useful management tool even to a neolithic herder he could  stay in his cave drinking home brew and napping flints until just before they started.

Perhaps the most intelligent herder cut notches on a stick for each day between mating and parturition then in the next year he could just tick off the days. This sounds the most plausible but I looked it up on the internet.

This is what I found:..... ancient shepherds would:

 " Note the position of the bright star Deneb on the horizon at dawn on the day the sheep were mated. They could then expect the lambs when the star Vega occupied the same position at sunset."

It seems rather complicated and requires an intimate knowledge of the galaxy, which they may or may not have had, after all they had plenty of time on their hands. I suspect however that they would rather be inside the cave by the fire drinking  and watching the Flintstones than outside on a cold, wet November evening looking at stars.

I have checked this out on my Phillips "Planisphere" , Deneb is in the Western horizon in November and Vega is in the East in April, perhaps some astronomer out there can enlighten me. In the meantime I'll stay with notches on my stick.