Curious observation: when a magpie is walking across our lawn, its head bobs backwards and forwards further than the length of its stride. This doesn't happen when it's running or hopping forwards, only when it's strutting. What, I wonder, is the evolutionary advantage of this behaviour pattern? It turns up in other birds too, but with magpies it's especially notable, as the bobbing emphasises the strut.

PS: Not sure whether this should go here, or in the Spring thread, or somewhere better. Now whoever shouted "in the bit bucket" can stay behind after class.