Post by Sam on Mar 15, 2018 6:04:36 GMT -5
I saw this Robin pecking around in a bare dirt patch yesterday. Though Robins eat softer foods like insects and worms and don't really need grit to grind their food, they do still need a calcium boost during their egg laying period, so ... here's another small project for you and especially the kids. It can be a learning experience for them. You can teach them about both aspects of birds, their digestion and that need for calcium. (The extra calcium is needed for the forming of new egg shells for the eggs about to be lain). Many birds do, however, need grit to aid in digestion. One example is the dove. It has a very active gizzard and needs to store grit inside its gizzard to grind weed seeds and other hard to digest foods.
Now for the project:
Use your empty egg shells for the grit. To do this you should first sterilize the egg shells. I rinse them first then sterilize in the microwave for about two minutes for a small batch like the six halves shown.
Once sterilized, I crush the egg shells into bits trying to get all the pieces smaller than a sunflower seed. In the photo I'm using my bean masher ... because I have one and wanted really badly to show it to you A spoon works just as well. The crushed eggshell will be placed separate from other foods put out for the birds. I'll put it on a low stone or log in an open area so that the birds can watch for cats, hawks and other predators (Gracie)
Here is more information that will help you explain all this to the kids.
THE CROP:
Not present in all birds, the crop serves more or less as a "doggy bag" when the bird eats. Let's say you're a Song Sparrow and you discover a weed just loaded with delicious-looking seeds, but the weed grows in the open. If you flit into the open area to eat the weed's seeds, you're making yourself vulnerable to predators who want to eat you. What to do?
What you do is to flit into the open and gobble up those seeds far faster than any stomach could possibly handle them, then fly to safety. You can do this because of your crop. For, as you cram in those seeds, a few at first go straight to the gut but, when that fills, further seeds begin detouring to the bag-like crop. Once the crop is full of seed, you fly to your favorite perch, and now there's not much to do but let your stomach digest. As those first seeds in the stomach begin working their way through the rest of the body, seeds stored in the crop automatically refill the stomach. If someday you pick up a bird, perhaps one that has flown into a window and you want to save it from the cat, if that bird has recently eaten, you well may be able to feel the crop in the chest area, feeling like a bag filled with grit right below the feathers.
THE TWO-CHAMBERED STOMACH:
The stomach is an amazing affair consisting of two chambers. The proventriculus is the first chamber. It secretes an acid for breaking down food, and is best developed in birds that swallow entire fish and other animals containing bones which must be digested. If you know a little chemistry, you'll know how amazing it is that bird stomach-acid can have a pH as low as 0.2. In most of North America there's a kind of bird known as a shrike, which eats small animals, especially rodents and songbirds. A shrike's well developed first stomach-chamber can digest an entire mouse in only three hours!
The gizzard:
The bird stomach's second chamber is known as the gizzard. If you've ever eaten a chicken gizzard you know how tough and rubbery it is. To accomplish what the gizzard does, it absolutely must be tough, for the gizzard's main function is to grind and digest tough food. Though the gizzard consists of very powerful muscles, it alone can't pulverize everything the typical bird eats; you know how hard uncooked rice and corn kernels are, and these aren't even considered hard types of grain.
Something other than muscle power is needed. This "something else" is acquired when grain- eating birds pick up grit and small rocks as they peck seeds from the ground.
This mineral matter accumulates in the gizzard, and ultimately the gizzard grinds the particles against the seeds, smashing them. Turkey gizzards can actually pulverize English walnuts and steel needles! Bird species that eat softer food possess less well developed gizzards. In some species, the gizzard remains small and insignificant during the summer when the diet consists of soft food such as flesh, insects, or fruit, but it grows more powerful during the winter when seeds are the main food. Since birds eat such a wide variety of foods, you can imagine that variations on the stomach theme are many.
Now for the project:
Use your empty egg shells for the grit. To do this you should first sterilize the egg shells. I rinse them first then sterilize in the microwave for about two minutes for a small batch like the six halves shown.
Once sterilized, I crush the egg shells into bits trying to get all the pieces smaller than a sunflower seed. In the photo I'm using my bean masher ... because I have one and wanted really badly to show it to you A spoon works just as well. The crushed eggshell will be placed separate from other foods put out for the birds. I'll put it on a low stone or log in an open area so that the birds can watch for cats, hawks and other predators (Gracie)
Here is more information that will help you explain all this to the kids.
THE CROP:
Not present in all birds, the crop serves more or less as a "doggy bag" when the bird eats. Let's say you're a Song Sparrow and you discover a weed just loaded with delicious-looking seeds, but the weed grows in the open. If you flit into the open area to eat the weed's seeds, you're making yourself vulnerable to predators who want to eat you. What to do?
What you do is to flit into the open and gobble up those seeds far faster than any stomach could possibly handle them, then fly to safety. You can do this because of your crop. For, as you cram in those seeds, a few at first go straight to the gut but, when that fills, further seeds begin detouring to the bag-like crop. Once the crop is full of seed, you fly to your favorite perch, and now there's not much to do but let your stomach digest. As those first seeds in the stomach begin working their way through the rest of the body, seeds stored in the crop automatically refill the stomach. If someday you pick up a bird, perhaps one that has flown into a window and you want to save it from the cat, if that bird has recently eaten, you well may be able to feel the crop in the chest area, feeling like a bag filled with grit right below the feathers.
THE TWO-CHAMBERED STOMACH:
The stomach is an amazing affair consisting of two chambers. The proventriculus is the first chamber. It secretes an acid for breaking down food, and is best developed in birds that swallow entire fish and other animals containing bones which must be digested. If you know a little chemistry, you'll know how amazing it is that bird stomach-acid can have a pH as low as 0.2. In most of North America there's a kind of bird known as a shrike, which eats small animals, especially rodents and songbirds. A shrike's well developed first stomach-chamber can digest an entire mouse in only three hours!
The gizzard:
The bird stomach's second chamber is known as the gizzard. If you've ever eaten a chicken gizzard you know how tough and rubbery it is. To accomplish what the gizzard does, it absolutely must be tough, for the gizzard's main function is to grind and digest tough food. Though the gizzard consists of very powerful muscles, it alone can't pulverize everything the typical bird eats; you know how hard uncooked rice and corn kernels are, and these aren't even considered hard types of grain.
Something other than muscle power is needed. This "something else" is acquired when grain- eating birds pick up grit and small rocks as they peck seeds from the ground.
This mineral matter accumulates in the gizzard, and ultimately the gizzard grinds the particles against the seeds, smashing them. Turkey gizzards can actually pulverize English walnuts and steel needles! Bird species that eat softer food possess less well developed gizzards. In some species, the gizzard remains small and insignificant during the summer when the diet consists of soft food such as flesh, insects, or fruit, but it grows more powerful during the winter when seeds are the main food. Since birds eat such a wide variety of foods, you can imagine that variations on the stomach theme are many.