Midwife Toads and Painted Frogs: Discoglossidae

Midwife toads and painted frogs are mainly active at night, which is when they hunt for food. During the day, they remain hidden under logs and rocks or in burrows. Not all of the members of this family dig their own burrows, but those that do, like the species that is known simply as a painted frog, use their front legs and toes to scrape their way into sandy ground head-first. They may pat firm the top of the burrow as they dig by butting the head up against it. Sometimes the frog digs only shallow burrows that go little farther than the length of its body, but at other times, the frog may dig a deeper, longer system with side tunnels. When the frogs leave their hiding spots at night, they tend to stay in fairly moist areas to look for food.

The males of all species call during the breeding season either from the water or from shoreline spots on land. In some species, the call sounds like chiming bells, and in others it sounds more like a series of high-pitched "poo" or "pie" noises. Unlike most other species of frogs, some females in this family also call. The Iberian midwife toad, for example, calls back when the male calls. Her call is similar, but quieter than his. Studies of the Iberian midwife toads show that females respond better to males who make faster but lower-pitched calls. Both male and female Mallorcan midwife toads also call. Some scientists believe that their calls do more than bring males and females together to mate. Their studies suggest that the toads, especially the youngest froglets—those that have just made the change from tadpoles—may listen to the calls simply to find out where other toads are, so they can join them in a safe place.

When a male and female mate, the male climbs onto her back and hangs on just above her back legs. From this position, she releases her eggs, and he releases sperm, which unite to start development. Here again, the painted frogs do things differently from the midwife toads. The female painted frogs may mate many times a night, laying up to 1,000 eggs in a single 24-hour period, and she may have more than one mating day in a year. The Iberian painted frog, for example, may mate on six separate days a year and lay a total of 1,500 eggs in a year. Females drop their eggs into the water, where they either stay on the surface or sink to the bottom. The eggs hatch into tadpoles several days later. The exact timing of the hatch depends on the temperature of the water. In Iberian midwife toads, for example, eggs in warm water can hatch in just two days, but eggs in cold water may need six days before they are ready to hatch. The young then remain in the tadpole stage until the next spring or summer, when they change into froglets. When they reach 3 to 5 years old, the young are adults and old enough to mate themselves.

The midwife toads are very unusual in the way their eggs develop. The process starts when the female lays strings of eggs, one string at a time. After 10 minutes or so, the male collects the strings and wraps them around his ankles, one after the other. By the time he is done twirling them around his legs, the male is wearing what looks like a skirt of beads. A single male may mate with several females, and some, like the Iberian midwife toad, may carry up to 180 eggs from four different females. The eggs of the Mallorcan midwife toad are larger, but fewer in number. The Iberian midwife toad's eggs are about one-tenth of an inch (2.6 to 3.5 millimeters) in diameter, and the female may lay 40 to 50 eggs at a time. The female Mallorcan midwife toad typically lays only a dozen or fewer eggs, but her eggs are twice the size at about two-tenths of an inch (5.4 to 7 millimeters) in diameter.

Regardless of the size or number of eggs, the male continues to wear and protect them until they are ready to hatch. At that time, he hops over to the water to allow the newly hatched tadpoles to swim off on their own. This unusual behavior of the male gives the toads their name: midwife toads. A midwife is a person who helps a woman deliver her baby. Although the male toad doesn't help the female bear her eggs, he does help make sure they hatch. Tadpoles of the midwife toads can grow quite quickly. Those of the Mallorcan midwife toad, for instance, can double their size and double it again in just a few weeks. Tadpoles make the change to toadlets, a process called metamorphosis (MEH-tuh-MORE-feh-sis), early the following spring and generally are old enough to mate when they reach their second year.