Sanderling The varying migration choices made by different birds I’ve seen recently has made me ponder the pros and cons of the various strategies they adopt. Most, if not all, life has one overriding driver, to produce viable offspring and hence perpetuate the gene line. Pretty much all bird behaviour derives from this one simple driver. Different birds adopt different tactics to deliver this, the key being how to be in prime condition when it comes to breeding season in order to attract a mate and successfully raise their progeny. Condition is largely determined by food supply and energy usage, put simply the question is how to consume the maximum amount of food while expending the minimum amount of energy. In northern climes there are two basic choices in winter. Firstly, stay put, save energy and hope there is enough food to see you through the winter. Secondly, expend a lot of energy migrating to warmer climes but hence ensuring abundant winter food. The other part of the...