RETURN OF THE RED-LEGGED FROG

Rex Burress

The Threatened Red-legged frog under the Endangered Species Act has returned to Yosemite Valley after an absence of ten years, so states a news item!

This is especially good news for Batrachophiles or Frogophiles [ frog lovers] to hear about California's largest and endemic frog that's in a stage of recovery. Most everyone enjoys the presence of Rana aurora draytonii, but the introduction of the much larger Bullfrog [Rana catesbeiana] almost wiped them out until the bullfrogs were controlled. It's like “reduce one predator species to save another species!”

Bullfrogs are very predaceous and will eat anything that moves, including the red-legged frog. Even drag a piece of cloth-bait before them on a cane fishing pole and they'll grab it, a method used by Eastern frog-leg hunters! Bullfrogs, snapping turtles, carp, and a bunch of non-native species are banned from being imported into CA because of this incompatibility prone to upset delicate balances of nature.

Nearly all frog species in California are in the foothill and mountainous regions ever since the valley lands have been taken over by agriculture, which involved the reduction of wetlands, the frog's favored habitat. The Yellow-legged Frog is also threatened and being considered now for the endangered list, but with President Trump's resistance to save land for ecological benefits, the move is in doubt [vote]. Amphibian's in general are having a tough time to survive. Even high mountain lakes have been stocked with alien trout that also devour Rana muscosa, the Mountain Yellow-legged frog.

Thus there are no red-legged frogs around Oroville, nor few other frog species in the drought-prone region, except for the tree frogs that put on an evening song-show in the spring.

Frogs have a universal interest, and especially are a fascination for kids. I remember frogs by the dozens jumping in the water as you walked along a Missouri waterway, or leopard frogs out in the moist creek-bottom meadows. They bring out the urge for a boy to catch them.

An extreme interest is in the reproduction methods of all amphibians, much like the fantastic story of butterfly metamorphosis. Frogs start out the process with the males making specialized calls to attract a mate. Like using an inflated drum, the throat pouches balloon to resonate their croak, and the get together is a lengthy coupling called 'amplexus,' sometimes lasting several days. All the while the female is pumping out strings of eggs in a mucous strip and the male is pumping out sperm for external fertilization. There is marvelous diversity, though, in reproduction methods.

Even more bizarre, a fish-like larvae hatches out, that slowly grows legs and retains the tail until it falls off later! This all happens in a couple weeks, and if puddle-tadpoles sense a dry-up, they can speed up development. I once studied a puddle of week-old tadpoles just starting leg growth. With the puddle almost gone, I went down next morning to save them, but they were all gone, not eaten by a bird, but fully developed into air breathers and hopping around in the grass!

There are about 7,000 species of frogs in the world, and about 300 in CA, including a few salamanders. They've been around a long time, at least 175 million years in fossil terms. Most species can tolerate freezing by going into a torpor, even under ice, and they estivate in summer heat, to live about ten years. The moist skin of frogs is sensitive and absorbent, an irritant in toads, and some South America 'Poison Dart Frogs' develop extremely poisonous skin from the poison insects they eat. Thus there are jungle tribes that make poison blow-gun darts. That's no small stuff when one Golden Dart Frog yields enough poison to kill 22,000 animals.

“The frog does not drink up the pond in which he lives.” --Indian Proverb