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I was over at Sweetwater Wetlands this morning. I noticed that the small man-made stream near the wetlands’ entrance was full of small frogs, dozens of them all crammed into an area a few yards long and a few feet wide. Intrigued, I took some photographs.
The frogs were rather small, about 2 – 3 inches long, and my first thought was that they were of some native species, perhaps Leopard Frogs. But, a quick glance at my images dispelled that notion. These are immature American Bullfrogs.
Bullfrogs are not native to Arizona. They are an eastern species, common to streams and ponds east of the Rocky Mountains. They were introduced to California in about 1900 by someone who thought that their legs would make for a food delicacy. They quickly escaped and spread like wildfire. They have become a major nuisance in western waterways because they threaten lots of native species and because they have few natural predators capable of making inroads on their population.
Although bullfrogs are an aquatic species they are capable of migrating over land. An adult can travel several miles from one body of water to the next. In that manner they have been able to populate even the relatively isolated bodies of water in southern Arizona.
An adult bullfrog will attain a length of about nine inches and weigh up to about two pounds. It is a voracious predator and will eat almost anything, including fish, small mammals like mice, birds, reptiles, and other amphibians. Several species have suffered severe depredations from bullfrogs, including Mexican Garter Snakes, which have been endangered to the edge of extinction.
Surprisingly, adult bullfrogs’ main source of food is — other bullfrogs! These animals are cannibals par excellence. Youngsters, like the ones in these images, are easy pickings for the adults and the adults consume their own offspring avidly. That doesn’t stop the species from multiplying like wildfire. A female bullfrog can lay about 20,000 eggs at one time and the tadpoles have few natural predators.
I found these youngsters to be kind of cute in spite of their nasty reputation. I just wish there weren’t so many of them.
Images taken with a Canon 5Diii, 400 DO assisted by Canon 600EX-RT Speedlite, ISO 500, M setting, f10 @ 1/160. As a technical note, I’ve never used a flash attachment to provide fill-in light with a long telephoto lens. These frogs were in very deep shade and shooting in ambient light proved to be impossible. So, more out of desperation than for any other reason, I put the flash on the camera and tried that. I was 2 – 3 meters away from my subjects when I made these photos. I shot at full flash power using a diffuser. I was surprised that the frogs didn’t flee the instant the flash went off, but generally, they stayed put. Perhaps they thought that the flashes were distant lightning strikes. I am very pleased with the results and I will be doing this more often in the future.