Calcium in the wild

[PythonWallace]

For all of the reptiles and amphibians that need calcium and D3 suplements, where do they get their daily calcium in the wild? I'd imagine some of the species get it from sand or egg shells, but can anyone explain where most of them get it, or why these animals evolved to need so much calcium when their main diet lacks calcium?

[Ginevive]

I am not sure about all herps. But I know about horned frogs, as I have one. I know that in the wild, these frogs will basically shove anything into their mouth that will fit, and that they can catch. This includes insects, other frogs, possibly small snakes and other creatures even. It is comical in a sad way, because when they congregate for breeding purposes, you can often see frogs biting into each other and trying to eat their potential mates. And these guys have a JAW! I got bitten by one of mine years back, and it drew a lot of blood and hurt like heck, like small saw blades cutting into my finger.
I know that in captivity, most people just feed crickets to juvies. Thus, vitamin powder is used, I guess because the frog is not getting the wide variety of foods that they get in the wild (including other frogs!) I feed my adult mostly rats now with occasional nightcrawlers. Many people's young horned frogs die as a result of calcium deficiencies and the weakened, deformed bones that result.

[Brimstone111888]

Only thing I can think of is, they eat a wider variety of food in the wild than in captive care.

[CeraDigital]

Bones of their prey is a source of calcium for snakes, and monitors, as well as other herps. Vegetarians, such as the Green Iguana need sunlight (UVA/UVB) so that they can produce D3. When Iguana's don't get enough calcium, such as D3, their bodies begin to absorb it from their bones, which causes weird warps, kinks, fragile/glass bones etc...number one cause of MBD...and the number one killer in Iguanas.

[fishmommy]

some vegetable materials are rich in calcium. moose up here need vast amounts of calcium and get it during the summer by feeding on a lot of aquatic plants rich in calcium.

[PythonWallace]

I understand about the herps that eat vertibrates getting calcium from bones like snakes do. I'm mostly asking about strictly insect eaters like smaller frogs and lizards. Are their diets gut loaded with calcium rich vegetable matter?