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Life cycle of a frog: A fresh start

As the new year gets fully underway, native amphibians are at their most visible. Breeding season is upon them, and they’re clustering around ponds everywhere in the hope of finding a mate.

The winter months saw our frogs, toads and newts hibernating in compost heaps, piles of dead wood or at the bottom of ponds. But temperatures are slowly rising, causing them to wake up and re-emerge into the big wide world.

It’s around this time of year that you will be able to see some of your local species, as they congregate around ponds in an attempt to mate. This process kicks off a new rotation of their life cycle.

Frogs mating
(Photo: P Hetherington/WTML)

Breeding

As the amphibians gather, every male attempts to claim a female. In frogs and toads, the males will clamber on top of the female. This causes the female to lay her eggs – up to 5,000 of them – which are promptly fertilised by the male.

Newts do it differently, with the male having to prove his worth by shaking his tail. If the female is suitably impressed, he’s allowed to mate with her. He presents her with a sperm-containing bubble, which she picks up to fertilise her eggs. After a few days, she starts to lay up to 12 a day. She may lay as many as 400 eggs in a season, each placed carefully under the leaves of aquatic plants.

Toad spawn in strings
(Photo: northeastwildlife.co.uk)

Hatching

In all amphibians, eggs hatch after one to three weeks (depending on water temperature). The resulting tadpoles initially live off the yolk that stays with them, but after a few days they need to feed. Frog and toad tadpoles feed on plant matter, whilst newt tadpoles eat microorganisms such as freshwater plankton.

Tadpole
(Photo: M Barton/WTML)

Metamorphosis

Tadpoles have to undergo huge physiological changes to survive on land. Their external gills become internalised, and their lungs develop. Eventually, the gill structures entirely vanish. This happens much earlier in frogs and toads than in newts. Limbs also form in this stage. Front limbs appear first in newts; hind limbs are first in frogs and toads.

More changes happen in frogs and toads as their lifestyle completely changes, but newts stay more constant.

Adult frog
(Photo: northeastwildlife.co.uk)

Juveniles

Due to a high predation rate, few tadpoles make it to this stage. If they do survive, they are developed enough to leave their nursery ponds. This usually happens around August, and all the survivors leave together. They then disperse across the countryside, ready to hibernate over winter.

Juveniles spend the next couple of years just eating and avoiding being eaten. Frogs and newts reach sexual maturity at around three years old, whereas toads only fully develop at four years of age.

Adult frog
(Photo: P Holmes/WTML)

Adults

Fully grown individuals only return to ponds when they are ready to mate. This migration can start as early as September. They reach the spawning ponds in February, following their hibernation. At this point, it’s warm enough for them to mate successfully, and the life cycle begins again. On average, frogs will live eight years, toads for 12, and newts for six.

Be on the lookout for these magical creatures this month. Here in the UK, we have seven species of amphibian. You’re most likely to see a common frog, common toad or smooth newt as they’re all widespread. If you’re lucky, you’ll be able to find a pool frog, a natterjack toad, a palmate newt, or even a great-crested newt.

Our native amphibians are getting busier with warmer temperatures, so why not see what you can find?

Hunt out a local pond or wood near you, keep your eyes peeled, and let us know what you can find!