Last updated on October 23rd, 2023 at 08:55 pm
Frogs and toads are among the beneficial animals in the open landscape and in the home garden. For some they are unwelcome garden inhabitants, for others they bring a little more nature into the home. Whoever owns a garden pond or other standing water has a good chance to welcome them one day. Water plays a major role in the reproduction and spawning of frogs and toads. Everything you need to know about this can be found here.
Contents
Frogs and toads
Many times the green hops are called frogs or toads, but they are two different species. Both belong to the order of frogs (Anura), but the toad species come from different families. In order to know which of the two species is present and when the spawning season of these is, they can be told apart based on the following differences:
- Toads are more terrestrial animals and move to water only to spawn – Frogs are water-loving.
- Toads do not have webbed toes as frogs do.
- Toad’s physique is more plump than that of frogs.
- toads move mostly by crawling/running – frogs jump mostly
- toads have front and hind legs of almost the same length – in frogs the hind legs are much longer and slimmer
- toad skin wrinkled, leathery, often with wart- or bump-like appearances – frog skin is mostly smooth and often shiny
Reproduction time
When frogs and toads reproduce depends on the species. Basically, early spring heralds the spawning season for the species that most often use the garden for spawning. These include:
- Jumping frogs in late February
- Grass frogs in early March
- Toad species between mid-March and early April
- Pond frog between late April and May.
Note: A loud “quacking orchestra” beginning in early spring is a clear sign that mating season is approaching.
Mating search
Frogs and toads are solitary animals, but the frog accepts conspecifics in the vicinity and therefore does not move in another direction. When mating season is upon us, it is time to find a female. In particular, more toad species can be heard trying to attract females with their luring calls, while some frogs may already have one in their sights at their location, but announce their readiness through their luring calls. These luring calls consist of loud croaking sounds that can be heard within a radius of up to two kilometers. For maximum volume, they use the so-called sound bubbles, as they are inflated on the side of the face. Some frog species make themselves heard much more quietly and croak under water.
Mating
If a pair of frogs has found each other for mating, this is carried out near water banks or directly in the water. In most species, males cling under female axils. Toads hold onto the loins of females for several days, but never for more than an hour at a time. In frogs and toads that spawn early, such as spring and grass frogs and common toads, males already “piggyback” on the females’ backs on their way to spawning water.
Eggs and fertilization
It takes about a week for the female toads and frogs to spawn. To do this, they look for a suitable spawning site, where they usually lay their eggs in several successive stages. Some females, after each egg-laying, move to another nearby site for the next egg-laying. Other species, such as green and brown frogs, however, lay their eggs all clustered together at once. Only after spawning does egg fertilization occur by the male’s sperm, which he spreads over the eggs with his hind legs.
Exception
Common midwife toad (Alytes obstetricans)
The reproduction/mating of the Common Midwife Toad, which is rarely found in European gardens, takes place exclusively on land. Once the female has released the eggs there, the male lays them around his hind legs and leaves them there for several weeks until they are about to hatch. Only then are they released into the water as tadpoles.
Spawning sites
In principle, all frog and toad species lay their eggs on or in standing water. The toad stays on land and looks for a suitable place at the water’s edge, or pulls so-called spawning lines from there around plants or branches standing in the water. The natterjack toad is special because it lays its eggs on the bottom of the water.
The frog spawns directly in the water. Either the frog eggs adhere to aquatic plants or they float as a compound ball on the water surface. The latter can cause large spawning carpets to form, up to several square meters in size.
Tip: If you want to discover the small eggs, look more closely, because then you will see jelly-like sheaths in the water, in which the eggs are located and holds them together so that balls and strings can form.
After egg laying/fertilization
Once the female has finished laying eggs, she usually leaves the site after the male has disengaged from her grasp. The female green frog is an exception, and males also remain at the spawning site. In some cases the “fathers” still take care of the offspring, while others are already on the lookout for the next females.
Mating frequency
It is not uncommon for males to mate four to five times. Most female toads spawn only once every two years. Female frogs usually mate once a year. The natterjack toad is an exception with several times a year. However, in addition to frequency, egg quantity is also interesting, as it varies greatly:
- pond frogs: between 300 and 400 eggs per year
- Common toad: between 3,000 and 6,000 per year
- Golden toad: about 230 eggs per year
- Green toad: between 9,000 and 15,000 eggs per year
- Aga toad: between 8,000 and 25,000 eggs per year
Egg development
Already in the eggs the development to the larva progresses. It takes only a few days until the first signs of a tadpole are formed. It takes further days until the jelly-like shell dissolves and the tiny tadpole can move unhindered in the water. Exactly when this process is complete depends on the temperature and frog/tadpole species. Generally, this covers a period between five days and four weeks from egg laying. In the case of the grass frog, it is usually after ten to 14 days.
The frog offspring can be recognized and distinguished from toad tadpoles by the following characteristics:
- Frog tadpoles average five centimeters in size – toad tadpoles only half that size.
- Frog tadpoles have external gills
- Black underside seen on toad offspring
- Frog offspring have eyes located at the edge of the body
- Toad tadpoles mainly swarm on water surfaces
Chances of survival
The chances of survival of the tadpoles are low. It is estimated that at least three quarters of the offspring do not survive because they become victims of their natural predators. One of the most feared predators is the yellow blister beetle of the diving beetle family (Dytiscidae), which can eat up to 900 tadpoles per day. Other predators include:
- Newts
- water bugs
- dragonflies
- water birds, such as ducks and herons
Tip: To prevent tadpoles from being eaten in the garden pond, it is advisable to stretch a close-meshed net over the pond with a distance of several centimeters to the water surface. This is the only way to prevent long-billed birds and insects from reaching the offspring.
From tadpole to frog
In order for the tadpoles to thrive, they feed on the jelly mass at the beginning and later on algae and plant parts. After 1.5 to two months the first extremities appear. The hind legs are visible first, while the front legs initially remain in “pockets” and emerge later. Further development occurs as follows:
- Two to three weeks after that, shedding of their rape mouth (for previous feeding).
- Discontinuation of food intake
- Feeding takes place exclusively through fat reserves
- Fat reserves come from the tail, which now recedes
- Front legs appear
- Now has the stature/body shape of a young frog
- After two to three days they go ashore
- Body size: about one centimeter
- Sexual maturity: one to three years, depending on weather and frog species
Young frog and toad
In the case of frogs, the young usually remain around the water body/garden pond for the summer. Only when they have grown somewhat do they move into shallow water. The exception is grass frogs, which, like the toad species, immediately set out for suitable habitat after leaving the water as frogs and land animals. They do not return until sexual maturity has occurred and the cycle of reproduction begins again.