Scientists studied the vernal window—transition period from winter to the growing season. They found that Warmer winters with less snow resulted in a longer lag tune between spring events and a more protracted vernal window. This change in the spring timetable has ecological, social and economic consequences — for agriculture, fisheries and tourism. As the ice melts earlier, the birds don't return, causing a delay, or lengthening in springtime ecological events.
With reference to the above passage. the following assumptions have been made:
Which of the above assumptions is/are correct?