[00:00.00] The bird’s bill is composed of a horny sheath over a bony core. [00:05.74]The entire structure has evolved in numerous ways to the specialized needs of its owner. [00:11.74]The bird’s bill is highly modified for a variety of activities—such as cutting and crushing seeds, probing tree crevices for insects, drinking nectar from flowers, catching fish, and so on. [00:25.74] There’s a large variety in the diets of birds throughout the world. [00:29.74]Different birds have evolved different bill types to assist in their feeding. [00:34.24]What I mean is, the shape of the bird’s bill is specially adapted to specific foods.
[00:40.74]A large number of birds are primarily seed eaters. [00:44.74]These birds typically have stout, cone-shaped bills and strong jaw muscles for crushing seeds. [00:51.74]The edible kernel of a seed is protected by a husk, or shell, which must be removed before the seed can be digested. [01:00.24]The smaller finches, sparrows, and grosbeaks use their heavy conical bills to process seeds by removing the outer covering before swallowing them. [01:10.44]Larger birds, such as pigeons and pheasants, swallow seeds whole and rely on grit in the gizzard to remove the husks and crush the seeds.
[01:20.44]A wide variety of birds are nectar drinkers. [01:24.44]These birds prefer the sweet liquid nectar of flowering plants. [01:28.44]The coevolution of birds and flowers has led to specialization, in which the bird’s bill is adapted for the collection of nectar. [01:38.44]The bill evolved so that it could reach the nectar at the bottom of a flower’s long tubular corolla. [01:45.44]Birds who drink nectar have long, narrow bills and tongues with finely divided tips that form a brush. [01:54.14]The tongues are very long, and the edges roll inwards to make a narrow scoop, so the bird can sort of lap up nectar, taking several licks every second. [02:04.84] The tongue holds the nectar by capillary action—a physical force that causes fluids to rise in narrow tubes. [02:12.84]The tongue moves in and out rapidly, carrying nectar up tiny grooves in the tongue, all the way to the mouth.
[02:20.84]Hummingbirds can stick their long tongues out far beyond the tips of their bills. [02:25.24] This enables them to reach the nectar at the base of flowers. [02:29.34]But along with drinking nectar, hummingbirds will also grab any insect they meet. [02:34.84]As they flit from flower to flower, they consume the flower’s nectar as well as insects and spiders that provide them with protein.
[02:44.84]Birds that eat insects collect their food in a number of ways. [02:47.84]The warblers have short, slender, tweezer-like bills, that they sort of use like tweezers to pick small insects off leaves and twigs.[02:57.44]Plovers pluck insects from the soil with their short bills. [03:01.74]Starlings have longer bills, which they push into the earth and force open to make a hole, and then look down the hole for insects.
[03:10.74]The insect eater’s tongue—like the bill—is specialized to the bird’s diet. [03:16.44]The tongue of some woodpeckers is long, sticky, and barbed, which makes it easier for the bird to catch its insect prey. [03:24.34]Several species of woodpeckers use their bills as wedges to pry the bark off trees to reach the insects underneath and then lap them up with their long, sticky tongues.
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