Adult frogs are carnivores that aren’t very picky with what they eat. Their generalist diet means frogs can find food in the variety of habitats they live in – from rainforests to mountainous areas to dry regions.
However, despite their diverse diets, frogs still sometimes find themselves in environments where food sources are scarce. So, how long can frogs survive without food?
In general healthy adult frogs can survive for 2- 4 weeks without food, provided they were well-fed before the period of starvation. Juvenile frogs and tadpoles can not survive long without food as they are still growing and have higher energy needs.
How long a frog can survive without food is influenced by several factors, including the frog’s health, stage of development, environmental temperatures, and time of the year.
Tadpoles Can Not Survive Long Without Food
Frogs start their lives as tiny embryos inside egg sacs. Their first food source for the developing embryos is the yolk of their eggs.
After hatching, the tadpoles , will spend the first few days feeding on the remaining yolk of the eggs. This will provide them with enough energy to grow and develop further.
After about a few days, the tadpoles would have developed enough to start free swimming and feeding on food sources available in the water.
At this early stage, frog tadpoles are mostly herbivorous, and will eat
- Algae
- Soft roots and leaves of aquatic plants (eg. duckweed mosses)
- Phytoplankton
- Detritus (mostly composed of degraded plant materials)
A few weeks into their development, the tadpoles start to grow legs, starting with the back legs. Their digestive tract will also gradually shorten.
Frog tadpoles at this stage become omnivores and will eat animal protein (such as mosquito larvae, and worms) in addition to plant matter.
Whatever they eat, they will eat constantly. They have high energy demands because they are growing very rapidly. Growing big as fast as possible is necessary for survival, as it enables them to escape their ponds before they dry up.
Since tadpoles have high energy demands, they can only survive for 24 hours to a few days without food.
Some species of tadpole have been known to eat smaller, vulnerable tadpoles when they face starvation.
Juvenile Frogs Cannot Survive Long Without Food
After a few months, to a few years (depending on the species) the tadpoles will go through a process known as metamorphosis, in which they will transform into juvenile frogs.
During metamorphosis, the thyroid gland secretes a growth hormone called thyroxine.
This hormone triggers the tadpoles to:
- Lose the gills, and develop lungs for breathing air
- Absorb the tail into the body
- Grow strong legs for moving on land
- Remodel other organs to form an adult frog
Once metamorphosis fully is complete, the tadpoles are now young frogs and will leave the water for a mostly terrestrial, or semi-aquatic life (depending on the species).
These juvenile frogs will grow into adult frogs over time.
Since Juvenile frogs are still growing, they have high energy demands and can not survive long without food.
As a generalization, most juvenile frogs can only survive for 3 days to a week without food.
Adult Frogs Can Survive 3-4 Weeks Without Food
In general, adult frogs can survive for 3 – 4 weeks without food if they are healthy and were previously well-fed before this period.
However, during hibernation (brumation), adult frogs can survive for several months without food.
This is because their metabolic rate is drastically reduced to a point where all their energy needs can be met without any food intake for extended periods.
Some frogs, such as the wood frog (Lithobates sylvaticus) can ‘freeze Solid‘ during the winter and stay that way for up to 8 months each year.
In this frozen state, Wood frogs will have no heartbeat, no muscle movement, no breathing– and will not consume any food or water.
In the spring, Wood frogs will thaw, their hearts will start beating again – and the frogs will resume their regular activities.
How Long Frogs Can Survive Without Food Is Mainly Influenced by 7 Factors
1. Species
Frogs of some species are genetically programed to be able survive without food for longer periods than those of other species.
As earlier mentioned, Wood frogs have special adaptations that enable them to freeze solid and survive without food for up to 8 months per year.
One species of frog, the striped burrowing frog (Cyclorana alboguttata) native to Australia can survive for years buried in mud without food or water. They do this when resources are scarce.
While buried, the frogs will be in a state of torpor and their cell metabolism changes drastically enabling the frogs to maximize the use of their limited energy resources without running empty.
2. Stage of Development
Most frogs (not all) develop in 3 distinct life stages: Egg, Tadpole, and Adult.
Female frogs lay eggs, usually in shallow, fish-free freshwater bodies.
After a few days to a few weeks, (depending on the species) tiny tadpoles will hatch from these eggs.
Over time, these tadpoles will go through a process known as metamorphosis, and develop into miniature frogs.
These juvenile frogs will grow into the adult frogs most people are more familiar with.
During these different stages of their life cycle, frogs will have different energy needs.
Tadpoles grow rapidly and need to eat a lot of food to support their development. Under ideal conditions, tadpoles need to eat daily and have food available at all times.
Juvenile frogs, while more developed than the tadpoles, are still growing and also have high energy demands and need to eat frequently, ideally once daily or every other day.
Adult frogs are fully developed and do not need as much nourishment as tadpoles or juveniles.
Most healthy adult frogs can survive for 2 weeks, and as long a 3 or 4 weeks without food provided they were well fed before this period.
However, in general, adult frogs should ideally eat at least twice a week to maintain optimal health.
3. The Frog’s Health
Health also plays a role in how long a particular frog can survive without food.
Healthy frogs can generally survive for longer periods without food than weak or sickly frogs.
For example, a frog with a broken leg may require more energy than a healthy frog.
4. How Well Fed the Frog Was Before the Starvation Period
A frog that was well nourished before the period of starvation may be able to survive without food for longer than an individual that was poorly nourished.
This is because the well-nourished frog would have built up more energy reserves enabling it to survive longer.
5. Environmental Conditions
The environmental conditions can impact how long a frog survives without food.
Frogs may be able to survive for longer periods without food in clean habitats, free of predeors, and have plenty of water.
Generally, frogs will be able to preserve their energy if they do not have to escape predators, or travel long distances to find water, or suitable hiding spots.
6. Temperature
Like all amphibians, frogs are cold-blooded (ectothermic) animals.
This means they cannot internally regulate their body temperature. Instead, their body temperature changes with the temperature in their surroundings.
In other, their environment is the main influence on their body temperature.
For example, a frog in an environment with a temperature of 30°C (86°F) has a body temperature very close to 30°C. In an environment with a temperature of 15°C (59°F), the body temperature of the same frog is around 15°C.
Being ectothermic means frogs will have a varied rate of metabolism, depending on the temperature.
Warmer water temperatures increase metabolic rates. This means frogs have to eat more often to meet all their energy needs.
On the opposite end, cooler temperatures allow frogs to conserve oxygen. This extends the time they can survive without food.
7. Time of the Year
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Winter
During the winter, frogs enter a state of hibernation (brumation) to protect themselves from freezing temperatures in the winter.
During hibernation, their metabolic rates fall and frogs can survive for several months without food.
That said, frogs need to “bulk up” to prepare for hibernation,
During this period, they will start to eat more than normal, to put on good body weight, and create energy reserves to maintain important bodily functions during hibernation.
If a frog does not adequately prepare for hibernation and create sufficient energy reserves, it may not make it through the winter.
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Summer
Freezing temperatures aren’t the only thing frogs have to worry about.
High summer temperatures are just as undesirable as the cold. This is where estivation (also spelled as aestivation) comes in.
Estivation is when an animal enters a state of dormancy to conserve energy when the environmental conditions are very hot and dry.
The breathing rate, heart rate, and general metabolic rate all decrease, just as they do in hibernation. Think of it as some sort of summer hibernation.
If the summer weather gets too harsh, frogs of some species will find a cool moist place and estivate as they wait for the rain to come and the temperatures to drop.
During estivation, frogs can survive for several weeks without food.
How Long Can Frogs Survive Without Water?
In general, highly aquatic frogs can only survive for a few hours without water outside of hibernation or estivation.
Terrestrial frogs, on the other hand, can survive without water from 24 hours to a few days, depending on the species, and environmental conditions.
That said, some frog species such as the Common coquí (Eleutherodactylus coqui) evolved to live in environments with low availability of undisturbed surface water to live in.
For this reason, they developed strategies that enable them to survive and thrive without direct access to water.
These frogs can re-hydrate entirely by absorbing moisture from moist soil, or any other moist material, such as damp leaf litter.
This adaption allows Common Coquís to live in forests, mountains, and even in urban areas – without the limitation of a direct dependency on water.
Sources:
National Research Council (US) Subcommittee on Amphibian Standards. Amphibians: Guidelines for the breeding, care, and management of laboratory animals. Washington (DC): National Academies Press (US); 1974. VI, Amphibian Management and Laboratory Care. Available from: https://www.ncbi.nlm.nih.gov/books/NBK217594/
Cramp, Rebecca L. (2005). The effects of aestivation and re-feeding on the structure and function of the gut in the green-striped burrowing frog, Cyclorana alboguttata. PhD Thesis, School of Integrative Biology, The University of Queensland.