A huge oak tree towers into the deep blue Californian sky. It has been dead for many years yet it is covered with thousands of acorns. How can this be? The answer lies with the acorn woodpecker (Melanerpes formicivorus). This industrious bird drills perfectly round little hidey-holes in the trunks of oak trees in which to stash its hoard of acorns. Where there isn't a suitable tree, a telephone pole is used. The birds spend all summer chiselling out the funnel-shaped holes and when the acorns are ripe, they are brought one at a time and tried out in several holes until a perfect fit is found - too tight and the shell gets damaged in the effort and the nut rots; too loose and it falls out. Even when a snug fit is found there is work to do later. As the acorns dry they shrink and have to be re-housed. With some stores numbering up to 50,000 nuts, the task is too much for a lone bird or even a pair and has to be carried out by a whole family group.
