Birds migrate long stretches, sometimes even thousands of miles between its breeding and non-breeding ground, a journey _____________ many hiccups, often perilous, but it doesn’t have the luxury to reproduce and blossom in a fixed habitat. It has to fly to a new spot, sometimes _____________ food, some other times to escape harsh winters, the reasoning the same each time-the desire to survive. Migration as a phenomenon is nature’s remarkable way of _____________ Darwin’s theory-‘Survival of the fittest’; the Syrian migrants _____________ the theory even more vehemently.