The curious beak of a crossbill ([Fig 6]) is to pick seeds out of pine cones.
A duck's wide beak, with a strainer at the edge, is to let water out while keeping food in. A spoon-shaped bill is to scoop up food, and a thin, flat one is to poke into narrow cracks.
Both parts of the beak, which take the place of our jaws, are called mandibles, upper and lower. Both of them can be moved, while we can move only our lower jaw.
Birds' tongues are as curious as their beaks. To all birds they take the place of a finger, as the beak takes the place of a hand, and they differ as much as the beaks from each other.
Fig 7.
Tip of Tongue of Downy Woodpecker.
Insect eggs are very small, and often packed snugly into cracks and corners, and the birds who eat them have a brush on the tip of the tongue, which brushes an egg out of its hiding-place very easily.
The nuthatch picks his small grubs out of crevices in bark with the four-tined fork at the end of his tongue.
A hummingbird's tongue can be used as a tube, to draw up the honey of flowers, or perhaps as a pair of tweezers, to pick out the tiny spiders that live there.