Movement of Birds I r It has been claimed that the tha Persians Per Per- I r 0 portions rV slabs and Arabs compiled complied of their calendar according to the tho I regular movement of the birds and the only mysterious part of ot this natural phenomenon to them was the destination of ot the flyers ayers During During Dur Dur- Dur- Dur During ing the earliest years of the Christian Christian Christian Chris Chris- tian era writers believed that swallows swallows I lows hibernated In hollow trees in inthe I the winter I I