Springtime is officially upon us and nature is waking up from its winter slumber. Days are getting longer; daffodils are blooming, and frog spawn is a plenty!
In Ireland, we have only one native frog species – the Common Frog or Rana temporaria. Frogs in Ireland are recognised as an internationally important species and are protected by the EU Habitats Directive (92/43/EEC) and the Irish Wildlife Act (1976, amended 2000). These important little fellows live to be on average between 7 & 8 years old and can be found in aquatic, terrestrial and urban habitats all over Ireland.
Frog Breeding Season
Now Spring has begun, so has the breeding season for the frog. In recent weeks, you may have begun to spot them as they wake from their Winter hibernation, to prepare for the mating season (typically February/ March). Did you know that some frogs will hibernate at the bottom of a compost heap, underneath logs, while others settle on the mud at the bottom of a pond, absorbing oxygen through their skin?
Once they do emerge you may hear the mating calls of the males that wait patiently for females at breeding grounds. Typically, the male will travel to the freshwater breeding site first and his impressive calls will attract females. Once the females arrive, the males may have a few boxing rounds to secure a potential mate at which point the “winner” will hop onto the female’s back, using his nuptial pads in a position known as amplexus. Spawning may occur at any time during amplexus, and the pair may even remain in this position for days before spawning.
Spawning itself may only last a few seconds during which time the female will release anywhere from 1000 – 4000 black eggs, and the male will release its sperm, quickly fertilising the eggs. The fertilised eggs are encapsulated by a gelatinous substance which absorbs water, swells, and floats to the surface. The eggs are well insulated and even eggs from other individuals will clump together providing warmth. The jelly-like substance itself, keeps the eggs up to 10°C warmer than the surrounding water. These capsules also protect the eggs and provide nourishment for the developing tadpole, until they hatch after approximately 10 – 21 days. Amazingly, when the tadpole reaches 2 days old, it’s eyes, mouth and external gills are formed, and it switches its diet to a diet of algae as it begins to swim like a fish! Tadpoles begin to lose their feathery gills when they are about 12 days old, which is when internal gills are formed.
By 5 weeks, what will eventually be two powerful hind legs begin to emerge and the lungs begin to form, pushing the tadpole to the surface of the water where it takes its first gulp of air! By 7 weeks old, the tadpole can use its teeth to eat plants, insects, and other tadpoles.
As the little tadpole grows bigger, metamorphosis into a froglet begins to take place. Their front legs begin to grow when they are about 10 weeks old, and the tail begins to be absorbed (absorbed fully at approximately 14 weeks of age). The tadpole has now become a froglet and will spend his time hiding in the nearby, damp vegetation or hanging out on the rocks near the water’s edge. These tiny froglets will be spending the next year growing, in fact, doubling in size. It isn’t until they reach sexual maturity in their third year that they can carry on this fascinating breeding cycle!
Many tadpoles will never make it to the froglet stage as they are quite sensitive and vulnerable to surrounding conditions and threats. However, only 1 tadpole for every 10,000 needs to reach maturity to maintain a population and that is precisely why we must protect our frogs, and their spawn. So how can we do this?
How to help the frogs
The best way as individuals that we can help the frogs is by setting up a suitable pond in our gardens that frogs can successfully breed in. Providing them with them rocks, logs, heaps of leaves and of course ample long grass and vegetation means they also have a place to hibernate after spawning and the froglets too will have a safe place to grow, feed and practice their hopping! You’ll find that each year the same males and females will return to your pond to reproduce because they have the ability to recognise the smell of the water and algae which is pretty impressive! These carnivorous frogs and froglets, will also help protect your flowers against slugs and insects too, which they love to eat!
Protect the Frogs Habitat
As a community, we can also take action. The biggest threat to our frogs is of course habitat destruction with over 50% of amphibian wetlands lost to peat extraction, drainage, and pollution. Frog’s terrestrial habitats suffer much the same fate as the wetlands, as hedgerows and ditches are being destroyed, cut back or damaged. As well as affecting the habitat of the frog itself, this loss of biodiversity affects the food source for the frogs also which of course has a knock-on effect for species such as the fox and otter, who rely on frogs as a nutritional source. Making sure we do not disturb our ditches, hedgerows, ponds, streams, and stream edges can play a massive part in protecting frogs and spawn during the breeding season. Frog spawn is incredibly delicate, and its removal is not only illegal, but can have a direct impact on the survival of this protected species.
So, if you see any spawn or indeed frogs or froglets, be sure to leave them as you find them, and please partake in the “Hop to It Irish Frog Survey” which is run by The Irish Peatland Conservation Council (IPCC). This survey enables researchers and conservationists to keep track of our one and only native frog species, it’s habitats, reproductive status, and any threats which may be arising in order to protect this vital species. You can find the survey here: Hop To It Irish Frog Survey Card – Irish Peatland Conservation Council – IPCCIrish Peatland Conservation Council.
You can also submit any sightings or photographs you might have to The National Biodiversity Data Centre database http://records.biodiversityireland.ie/index.php
Written By Natalie Cunningham
Rana temporaria, Common or Grass Frog (freenatureimages.eu) Rana temporaria 52, Bruine kikker, Saxifraga-Hans Dekker
Rana temporaria, Common or Grass Frog (freenatureimages.eu) Rana temporaria 47, Bruine kikker, Saxifraga-Luc Hoogenstein
Rana temporaria, Common or Grass Frog (freenatureimages.eu) Rana temporaria 12, larvae, Bruine kikker, Saxifraga-Kees Marijnissen
Rana temporaria, Common or Grass Frog (freenatureimages.eu) Kikkervisje van Bruine kicker. Picture is taken in a cuvet filled with water from a pond
Rana temporaria, Common or Grass Frog (freenatureimages.eu) Rana temporaria 48, Bruine kikker, Saxifraga-Marijke Verhagen