How Many Tadpoles Survive?

Frogs lay eggs in substantial quantities, typically ranging within the hundreds to several thousands.

While laying large numbers of eggs helps have a drastic impact on species continuation, overall, only a small fraction of tadpoles survive long enough to develop into mature adults capable of reproduction. 

Approximately 2% of frog eggs become tadpoles, 0.8% of tadpoles become froglets, and 0.1% of froglets become mature frogs capable of reproduction. However, these figures vary based on frog species, predation, and habitat. Some favorable environments may see higher average survival rates of 1 – 2%.

Tadpoles can survive in a wide range of environments.

But, they are incredibly fragile creatures and are threatened by many dangers in the wild.

Join me as I discuss average tadpole survival rates and assess the aspects influencing higher or lower tadpole survival rates in the wild and in captivity.

Only a Small Percentage of Tadpoles Survive

Amphibians face countless threats from the beginning of their metamorphic journey.

Here is a quick overview of frog tadpole survival rates (Thurnheer, 2000):

Only a small fraction of tadpoles survive to become froglets, and only a minor portion of this group will typically survive long enough to mature and reproduce. 

Frog Egg Survival Rates

Since amphibians encounter a barrage of threats from their initial conception, it must be noted that any zygote that survives long enough to emerge from its embryonic state is already within the minority.

Frog eggs are preyed on by many different predators, meaning only a fraction of frog eggs become tadpoles in the first place. 

The following table provides an example of frog egg survival rates based on the figures above:

On average, only 1 in 50 (2%) frog eggs survive long enough to transform into tadpoles.

Using this estimate as a guide, only around 400 frog eggs would survive and transform into tadpoles if a female frog had laid 20,000 eggs during the mating season.

This ratio must be understood as a base or as a general rule, as tadpole survival percentages and averages are not based on the total number of frog eggs laid by a mature frog. 

Let me explain further.

Tadpole Survival Rates

In a study conducted by the University of Zurich, Switzerland (Thurnheer et al, 2000), the average survival rates of tadpoles were studied across numerous aquatic habitats.

The study intended to assess the potential for tadpole survival in various environments while identifying crucial aspects for overall well-being and longevity. 

Researchers assessed the weekly decrease in tadpole population across six ponds, varying in environmental characteristics and climates. In three of the six ponds, none of the tadpoles survived at all.

The study found that the survival rate of tadpoles till their next metamorphic stage averaged at only 0.8%.

Froglet to Maturity Survival Rates

Based on that study, if only around 0.8% of tadpoles survive to become froglets and leave their aquatic habitat, very few froglets will survive long enough to reach full maturity.

The researchers further assessed the survival rates of the studied tadpoles into their adult life and gathered the following information over a few years:

Based on the study’s further observations after the tadpole phase, it was estimated that only 0.1% of tadpoles survived to see adulthood.

Species continuation is affected by these figures, as the number of females that survive to mature and reproduce plays a large role in the process. 

Higher Tadpole Survival Rates

However, the study’s findings represented figures approximately 10 to 20 times lower than most investigations.

Since this figure differs between environmental contexts and species, other studies have identified more optimistic average tadpole survival rates. 

Figures reported by Sjögren reflected an average tadpole survival rate of 1 – 2 %, while other studies estimated that tadpole survival rates may average at around 1%.

Higher survival rates typically occur when the environmental conditions are favorable, and more frog eggs survive to become tadpoles in the first place. 

Factors That Influence Tadpole Survival Rates

The main factors that influence tadpole survival rates include frog species, predation, natural selection, availability of adequate food, and an appropriate habitat.

This is true for frogs in the wild as well as in captivity.

Numerous factors are responsible for the tadpole survival rates in different contexts, apart from potentially superior genetics or poisonous secretions depending on the frog species.

These factors generally lead to a larger fraction of some clutches surviving in most cases, while entire clutches may not survive at all in other cases. 

Predators 

Tadpoles are feeble creatures with next to no tools to defend themselves against hundreds of predators.

They generally avoid being eaten by hiding in dense aquatic vegetation, having an unpleasant taste or odor, and being toxic in some cases. 

However, these tactics do not always protect them from the large and hungry lifeforms in their shared habitats, and predators play a large role in how many tadpoles survive.

Many mammals and small vertebrates feed on frog eggs, tadpoles, froglets, and frogs, and the predator to prey ratio affects tadpole mortality rates. 

Natural Selection

Despite the presence of predators overall, tadpoles may gain advantages or disadvantages by additional factors attributed to natural selection.

This conflict often concerns their visual qualities compared to their surroundings, as tadpoles that camouflage more easily will naturally have higher odds of evading predators (CTNF). 

Tadpoles may also feed on their siblings if there is not enough food or space in their natural habitat or enclosure.

Water Bodies

Water quality plays a massive role in tadpoles’ health and longevity, irrespective of the species or habitat.

The water chemistry can directly affect their mortality rates or indirectly affect their health by lowering their productivity.

Tadpoles need shallow freshwater habitats, and they typically develop more effectively in warmer waters. 

The water’s oxygen levels also impact their health, as does the pH balance.

Water quality also contributes to the growth of aquatic vegetation and algae, further supporting their needs.

Tadpoles generally prefer newly formed water bodies, as there are fewer predators and competition for food sources. 

Food Availability 

Tadpoles feed on their remaining yolk sustenance for the first few days, after which they begin finding food in their habitat.

Tadpoles need sufficient vegetation during their early phases and access to small invertebrates during later phases. 

When the environmental conditions are appropriate, tadpoles gain the advantage of a diverse range of food sources.

But, they will die of starvation if there is a food shortage in their habitat, which is often a side effect of overpopulated water bodies. 

More About Tadpole Survival Rates

Although witnessing hundreds of little tadpoles swimming in a pond may seem like a frog infestation waiting to happen, these large numbers are generally temporary.

In most cases, a small percentage of tadpoles survive, and only the fittest or luckiest tadpoles live to see adulthood.

Learn more about tadpole and frog survival rates on our blog:

• What Do Tadpoles Need To Survive?
• How Do Frogs Survive?
• Can a Frog Survive a Broken Leg?
• Frog Hibernation: How Frogs Survive Winter

Sources

Sylvie Thurnheer, Heinz-Ulrich Reyer, Spatial distribution and survival rate of water frog tadpoles in relation to biotic and abiotic factors: a feld experiment, Zoological Institute, University of Zurich, 8057 Zurich, Switzerland, Corresponding author: H.-U. Reyer. 2000.