Why Do Frogs Lay Large Numbers of Eggs? (6 Reasons)

In the wet season, many frogs migrate to wetlands and other breeding sites to lay their eggs. In some species, such as the wood frog, many females congregate and lay their eggs communally, so it’s common to find large stretches of frog eggs floating in the same pool.

Most frogs lay large numbers of eggs as a natural way to counter the high mortality rates they experience in their early life stages. It is estimated that only 2% of frog eggs laid will survive to adulthood. The rest will be lost to predators such as newts and turtles – and also to the environmental conditions. 

The large number of eggs laid by each frog is important for the survival of their species. If just a handful of eggs become adult frogs and live long enough to breed, the population of that species should remain stable.

How Many Eggs 22 Frog Species Lay

Most frogs are seasonal breeders, and will only lay eggs 1 to 3 times per year, usually in the spring or summer months after a heavy rain.

Over the course of the breeding season, a single frog can lay anywhere from a few hundred to as many as 20,000 eggs, depending on the species.

In some frog species, female fecundity (capability to produce offspring) increases with body size, so large females may lay more eggs than smaller females of the same species.

For example, most Cuban tree frogs only lay about 3,000 eggs, but large females can lay more than 15,000 eggs in one breeding season!

Below Is a Table That Shows Approximately How Many Eggs 15 Frog Species Lay at a Time.

Frog Species
Scientific Name
How Many Eggs They Lay (Approx.)
Wood frog Lithobates sylvaticus 1,000 – 3,000
Pickerel Frog Lithobates palustris 700 – 3,000
Northern Leopard Frog Lithobates pipiens 300 – 6,500
American bullfrog Lithobates catesbeianus 6,000 – 20,000
Green frog Rana clamitans 1,000 – 7,000
Gray tree frog Hyla versicolor 1000 – 2,000
Spring peeper Pseudacris crucifer 750 – 1,200
American green tree frog Hyla cinerea 300 – 1,000
River frog Rana heckscheri 6,000 – 8,000
Australian green tree frog Litoria caerulea 200 – 2,000
Northern cricket frog Acris crepitans 200 – 400
Pacific tree frog Pseudacris regilla 400 – 750
Crawfish frog Lithobates areolatus 3,000 – 7,000
Pig Frog Rana grylio 6,000- 10,000
Carpenter frog Rana virgatipes 200 – 600
California red-legged frog Rana draytonii 300 – 4,000
Cascades frog Rana cascadae 300 – 800
Oregon spotted frog Rana pretiosa 250 – 1,000
European common frog Rana temporaria 300 – 4,000
American toad Anaxyrus americanus 2,000 – 20,000
Cane toad Rhinella marina 8,000 – 35,000
Asian common toad Duttaphrynus melanostictus 6,000 – 40,000
Fun fact: If every egg from one pair of American bullfrogs survived to adulthood, and each frog lived for five years, and all the eggs from their descendants survived, the entire surface of the earth would be covered in bullfrogs in less than 2 decades.

The Reasons Why Most Frogs Lay So Many Eggs

There are many reasons for frogs to lay as many eggs as they do.

1. Most Frogs Abandon Their Eggs After Laying Them

Most frog species do not show parental care for their eggs. After the mating is complete, both the males and females will leave the pond, abandoning the eggs.

This means the eggs are all on their own and are at the mercy of the environmental conditions. They are also easy meals for lots of predators.

2. Many Frog Eggs Are Lost to Predators

Frogs often lay eggs in open ponds and other water bodies – where predators accumulate over the course of the breeding season.

A large number of frog eggs are eaten by newts, turtles, leeches, dragonfly larvae, diving beetles, and other large water bugs.

Eastern newts often prey on frog eggs
Eastern newts often prey on frog eggs.

It’s common for over 75% of frog eggs in a pond to be wiped out by predators before they hatch.

3. Frog Eggs Are at the Mercy of the Environmental Temperatures

Many frogs have extended breeding seasons and their eggs are exposed to a wide range of temperatures depending on the time of year when they are laid.

For frog embryos to develop normally, the surrounding water temperature should stay within a certain range.

If the temperatures fall beyond their preferred range, their development rate decreases, meaning they will take longer to hatch. And if the temperatures drop too low, the embryos can die.

On the opposite end, if the temperatures rise above the preferred range, the developing embryos may overheat which can lead to a very high mortality rate.

Since most frogs lay their eggs clamped together, the eggs closest to the outside of the egg mass are the most vulnerable to the elements – especially if they are exposed above the water’s surface.

4. Frog Eggs Are Vulnerable to UV-B Radiation From the Sun

Unlike reptile or bird eggs, frog eggs do not have a hard outer shell to protect the developing embryos. Rather, each egg has a jelly coat.

This jelly coat absorbs UV-B radiation, and also indirectly protects the eggs by virtue of its sticky texture and its tendency to accumulate a covering of pond debris.

However, the protection the jelly gives is only limited, so frog embryos are still vulnerable to certain doses of UV-B radiation.

Many frogs lay their eggs in well-shaded water bodies to protect the eggs from direct sunlight.

But some frog species such as the Northern red-legged frog (Rana aurora) often lay their eggs at the surface of the water, in direct sunlight.

Wood frog eggs laid in direct sunlight
Wood frog egg masses laid in direct sunlight. Photo by: Adam Garrity (CC BY-NC 4.0)

Exposure to high levels of UV-B radiation can degrade the eggs of many frog species – and lead to lower hatching success.

High doses of UV-B radiation have also been shown to increase deformities in the embryos of some amphibians.

The embryos of most species of frogs and toads that breed in open water are nearly black – due to high concentrations of melanin in their dorsal hemisphere, which serves as protection from ultraviolet radiation.

5. Frog Eggs Are Vulnerable to Pathogens

The eggs of many frog species are susceptible to infection from pathogens and fungi such as water mold (Saprolegnia).

The eggs are especially vulnerable to infection when they have been weakened by environmental stresses such as UV-B radiation or unusually cold weather.

Infection of frog eggs by fungi sometimes causes catastrophic losses of reproductive effort.

6. Most Tadpoles Do Not Survive Long Enough To Become Frogs

When the tadpoles hatch, they too will have very low survival rates.

Many tadpoles often hatch into crowded pools, and there will be intense competition for food and limited resources, meaning again the number of tadpoles will naturally thin out.

Many species of tadpoles are even known to eat smaller, vulnerable tadpoles – further reducing the numbers.

When the tadpoles develop into froglets and leave the water, only a few will live to adulthood and reproduce, – which can be as low as 1%

The rest will get eaten by predators such as snakes, raccoons, and a wide variety of birds.

Many frogs are also run over by cars, or indirectly killed by humans in other ways before, they ever get to reproduce.

Given all these factors, the large numbers of eggs laid by each frog are crucial to the survival of its species. If just 2 out of 1,000 eggs laid become adult frogs and live long enough to reproduce, the population of that species should increase.

Some Frog Species Only Lay a Few Eggs

Some frogs such as poison dart frogs (Dendrobatidae) and glass frogs (Centrolenidae), only lay a few dozen eggs at a time. The reason for this is, that they breed in more favorable environments – so, their offspring generally have higher survival rates.

Poison dart frogs and glass frogs are even known to protect their offspring – which improves the survival rates.

Atrato Glass Frog Hyalinobatrachium aureoguttatum with eggs
Male Atrato Glass Frog protecting its eggs. Photo by: jorgebrito ( (CC BY-NC 4.0)

Generally, about 10 – 20% of all known frog species show some form of parental care. In these species, parental care may include the protection of eggs and/or tadpoles, transporting of tadpoles, feeding of tadpoles, or brooding of eggs.

For example, in many glass frog species, the mothers brood the eggs during the night the eggs are fertilized, and the fathers stay with the eggs to guard them for much longer periods.

Female horned marsupial frogs (Gastrotheca cornuta) carry their eggs in a pouch on their back until they hatch as fully developed frogs.

Darwin’s frogs ‘swallow’ their tadpoles, and put them in their specialized vocal sacs – then release them as fully metamorphosed froglets.


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