A chirping chorus or low rumble in the spring may be many things, but it could signal the mating call of various frog and toad species. While mating rituals, calls and acts vary between species, many aspects are common. Whether in captivity or the wild, most species will perform various actions throughout the mating session, albeit not always involving a romantic encounter.
In the wild, many male frogs wake from hibernation and start making their way to their breeding grounds -- typically a pond -- before the females show up. Each male in the species, and sometimes even subspecies, have distinctive mating calls to attract females. Some calls are high-pitched chirps, some are more songlike, and some are deep, low rumbling sounds. Because a certain body of water may be the breeding grounds for dozens of individuals and even different species, breeding season often comes with a chorus of different calls.
Male frogs climb onto the female's back in an act known as amplexus. Males have nuptial pads on their forelegs to help grasp onto the female. Several amplexus positions occur across different species; however, the main goal of the act is for the male to be able to fertilize the female's eggs.
In some cases, numerous males try to mount a single female at a time, resulting in a spectacle known as a mating ball. Females of certain species, including Rhinella proboscidea, sometimes drown in this intense mating competition. The males, however, squeeze the sides of a dead female's body to release her eggs and subsequently fertilize them.
Most frogs reproduce through external fertilization. This means the male's sperm does not meet the eggs inside the female's body. When the female releases her eggs into the water during amplexus, the male releases his sperm to fertilize them.
Some species reproduce via internal fertilization, in which the male frog's sperm fertilizes the eggs inside the female's oviducts. Some of these species give birth to tadpoles, meaning the eggs develop and hatch within the female.
Females often lay clusters or long strings of eggs in the water where they are more protected and won't dry out. When the eggs hatch, the hatchlings and tadpoles look more fishlike than froglike: Their legs aren't visible at first and they have a long, paddlelike tail. As they grow, the tadpoles go through metamorphosis and major transformations: Rear legs become more distinct and the mouth and jaw become more froglike. When approaching adulthood, the forelegs become more developed and visible and the tail continues to fade.
- University of Florida - Florida Wildlife Extension: Frequently Asked Questions About Frogs and Toads
- BBC Earth: The Mating Habits of Frogs in Spring
- The National Center for Biotechnology Information: Developmental Biology, 6th Edition; Scott F Gilbert
- National Geographic - Phenomena: Male Frog Extracts and Fertilises Eggs from Dead Female
- The Scientist: Unique Frog Breeding
- Photo Credit MatthewJWilliams/iStock/Getty Images