I'm just wondering what kind of frogs could they be to be able to eat something as big as a sparrow?
Another member posted a reply here at the same site above and posted a link to a news story on African clawed frogs that are eating things like turtles, fish and each other.
A lot of people keep frogs as pets, much like snakes and lizards. Many of these creatures fall under exotic pets. The African clawed frog is an example, because of its uniqueness and is popular among frog fanciers. Like a lot of people, I was not aware that a frogs diet went beyond eating bugs until your question. I did a bit of research on your question and this is the basics of what I learned.
The larger portion of a frogs diet consists of spiders and snails and since they are a scavenger anything that they can fit into their mouths is considered dinner. They are an opportunist and will take advantage of any small animal that is unwary. Please note that this is not limited to any specific breed or variety of frogs.
The frog in the article upon maturity reaches the length of 5 inches, this is quite large in comparison to the common sparrow. If you include the tail feathers in its length it is basically the same size. National geographic has a video on youtube showing a bullfrog feeding on a wide variety of creatures, and yes it did catch and eat a sparrow.