Common Frog

What our animals are doing this month…

May 1, 2024 by Admin

Late spring or early summer is a good time to be on the lookout for tadpoles! You might spot common frog or common toad tadpoles or, if you are lucky and on the coast, you might even spot natterjack toad tadpoles!

You might have spotted a few tadpoles already as frogs can lay their frogspawn as early as January and it can take two to four weeks for tadpoles to hatch out. As the tadpoles grow, they become faintly speckled with gold/brown and will slowly grow back and front legs!

Common toads breed a little later than common frogs, laying double strings of spawn and wrapping it carefully around vegetation. Again, it will take two to four weeks for the tadpoles to hatch out. To tell the difference between frog and toad tadpoles, you simply have to look at their colour. Toad tadpoles remain jet black and can also form shoals so can be easier to spot.

Natterjack toad spawn. Credit: Matt Wilson

The natterjack toad is confined to just a handful of sites on the coast in the UK and is only found on the Solway Coast in Scotland. Breeding for natterjack toads takes place in March/April but can continue into the early summer. So, depending on the natterjacks in your area, you may see males waiting by the pond edge (making loud rasping noises to attract the females), natterjack toad spawn or even some tadpoles! Natterjack toad spawn is laid in single strings with their tadpoles being smaller than common toad tadpoles and sporting a grey spot on their throat.

Always remember to record your amphibian and reptile sightings on our FREE Dragon Finder app. All of the data collected is sent to the National Biodiversity Network Atlas. You can download the app here.

Croaks on croaks

March 1, 2024 by Admin

Written by Jade Walton, Transforming Lives Trainee.

What is the difference between a frog’s croak and a toad’s croak? It would be easy to think that their croaks surely sound the same, or at least so similar that it would be very hard to tell the difference. This, however is not the case. Here is a quick guide to the calls of the common frog (Rana temporaria), the common toad (Bufo bufo), and the natterjack toad (Epidalea calamita).

Common frog

Relative to the call of the common toad, common frogs have a rather low-pitched croak. The sound is fairly smooth and repetitive. It is a comparatively soft call when compared to our native toad species.

Common toad

The common toad’s call is a much higher-pitched and stark sound than the common frog. Sounding like a rough ‘qwark-qwark-qwark’, its croak could easily be mistaken for the call of a duck or goose.

Natterjack toad

The natterjack toad has a distinctive call for multiple reasons. Their call is very raspy and higher in pitch than the common frog. The sound of their call carries for long distances, and can be heard from up to 2km away in the right conditions.

To hear the croaks of these species, as well as other amphibian species which may be found in the UK, download Froglife’s Dragon Finder app. Alongside recordings of croaks, the app can aid you in reptile and amphibian identification and allows you to report sightings of any reptiles and amphibians you may find in the wild.

The Basics of Scientific Naming

September 28, 2023 by Admin

Written by Madeleine Barnes, Transforming Lives Trainee

The scientific names of species seem incomprehensible to many people – but peeling back just one layer of confusion reveals how simple they can be to understand. Despite commonly being called ‘Latin names’ due to the prevalence of Latin-based words and a limit of only using the 26 Latin characters, scientific names can actually be made with any language and can even be complete nonsense. Typically, the names describe a species physically, but may also be the names of people or even simply be jokes (see the frog genus Mini).

The first international rules for naming animals were established in the “International Rules on Zoological Nomenclature” published in 1905. Each scientific name is a binomial name, meaning they are composed of 2 parts: the genus and species of the animal. They are always written in the format Genus species, with an added subspecies for a trinomial name if necessary.

Here are the scientific names of some of the species Froglife protects, and their meanings:

Common Frog – Rana temporaria

Translated directly from Latin as ‘temporary frog’, this name refers to how frogs seem to be absent during the colder months.

Great Crested Newt – Triturus cristatus

‘Triturus’ is Neo-Latin (Renaissance-era Latin) derived from the name “Triton”, a Greek god of the sea. In Latin, ‘crista’ means “plume on a helmet” or “tuft on an animal’s head” (typically referring to chickens), which describes the eponymous Great Crest on these male newts.

Grass Snake – Natrix helvetica

From the Latin ‘natrix’, meaning “water snake” – grass snakes are often spotted on water due to their preferred diet of amphibians. In Neo-Latin, ‘helvetica’ means “Swiss”, referring to this snake’s prevalence in central Europe.

NOTE: the barred grass snake was reclassified in 2017 from its previous classification as a subspecies of Natrix natrix, due to genetic testing marking it as a distinct species.

Adder – Vipera berus

‘Vipera’ is a contraction of the Latin ‘vivus’ (alive) and ‘parere’ (to deliver), indicating a snake that gives birth to live young. ‘Berus’ is a misspelling of the Latin ‘verus’, meaning “true” or “authentic” – this could refer to the adder’s reputation as a historical staple of Europe.

Slow-Worm – Anguis fragilis

Being a legless lizard, ‘anguis’ rather confusingly means “snake” in Latin – 1758 Linnaeus was clearly deceived by their snake-like appearance. ‘Fragilis’ means “fragile”, describing the way in which slow-worms drop their tails when in danger.

To learn more about the rules regarding naming animal species, access the International Code of Zoological Nomenclature online: https://www.iczn.org/the-code/the-code-online/

What our animals are doing this month…

September 26, 2022 by Admin

As we head into October and autumn our amphibians are finding places where they can overwinter.

The common toad will have spent most of the summer in its terrestrial phase where they have left their ponds in search of food. During daylight hours, they will have remained hidden under logs, stones, or leaf litter and will only appear at dusk and after dark to forage.

They typically move between 50-500m away from their ponds for foraging and their usual tactic is to sit and wait for food items to pass by. However, when autumn arrives, our common toad will return to areas near to their breeding pond (common toads always return to the breeding ponds where they were born). Before reaching the pond, they will find somewhere nearby to overwinter, this could be a hibernaculum, rockery, a hole in the ground or even a wall. Here they will stay to keep warm in the colder months.

The common frog is similar to the common toad wherein they will also begin overwintering in similar sites in October and November. Timing depends on location, altitude, and average daily temperature. Most common frogs do not emerge until February, however, on occasion the common frog is seen in mid-winter when weather conditions are milder.

The natterjack toad starts to disappear and overwinter a little later than the common toad and common frog, with it disappearing in late October to overwinter from November onwards. Where they choose to hibernate is still a bit of a mystery! but it could well be in sand dunes, in log or rock piles or mammal burrows.

What our animals are doing this month… November 2020

October 27, 2020 by Admin

We’ve recently covered what our amphibians and reptiles are up to over the autumn months, the differences in their overwintering behaviour and where they may spend the colder seasons in structures such as hibernacula.

It might surprise many however to hear that November can be a month for sighting Common Frogspawn in the south of England. Common frogs usually begin breeding and laying spawn as spring commences – often with sightings in January and February into spring depending on their location in the UK. But areas in Cornwall do report sightings of frogspawn before winter even fully commences.

This behaviour could be due to confusion during mild autumn and winter months that we can experience now in the UK or might be a strategy to get ahead of the game in terms of breeding times – albeit it with a huge risk of freezing temperatures affecting the survivability of the spawn.

This could be one sign of more to come in terms of our amphibians adapting to the effects of climate change and seasonal differences their behaviour isn’t quite adapted to. It’s so important that we can monitor these yearly trends in our amphibian and reptile species to help inform our work at Froglife and you can help by submitting your sightings using the Dragon Finder App – available for free on Android and iPhone devices!

*Frogspawn in November? Surely not! But this sighting can occur in mild autumns in the south of England*

Croaking Science: Do frogs and toads change their colours and if so, why?

October 30, 2015 by Admin

Froglife have been running an enquiry line and an email advice service for a very long time now and some issues have been reappearing regularly over the years. Most of those have been incorporated in the FAQs on the website specifically to facilitate the rapid dissemination of information to people searching for it. However, other topics are more complex and there is no short answer to some questions. For example: Do amphibians change their colour and if so what is prompting that change? Is it an adaptation to match the background colour (i.e. a toad is brown on brown soil but becomes dark grey when moving onto a gravel substrate to blend in), is it a seasonal change (lighter in spring but dark in autumn), is it an indication of disease or stress or is it when they are breeding?

Common Frog in autumn Silviu — S. Petrovan

It has been well described how colour can change in many amphibian species due to environmental conditions such as humidity and especially temperature and often frogs and toads or even salamander larvae are much darker when their body temperature is low. The common toad (Bufo bufo) however can have significant variation in dominant colour depending on age and some salamander larvae become lighter as they age, probably because early in the season there is a clear advantage to be darker and warm up quicker in cold water but later on dark larvae are at higher risk of predation. There is equally some evidence that in some species, including the common toad there is a certain level of adaptation of the colour depending on the predominant substrate in the area where they live. Probably toads that stand out (brown toads in dark grey soils) are more in danger of predation and as such there is a level of predation selection. Complex mechanisms are involved in relation to the colour change in most amphibians, including the common frog (Rana temporaria) in relation to the background colour. Confusingly, tree frogs in Europe are known to change their colour dramatically between dark grey in early morning to bright green or light grey later by mid-day yet neither of these species is particularly adapt at changing their colour to match that of their environment. Similar species of treefrogs from North America however do change to adapt to their background.

Some amphibians also dramatically change colour during breeding, with the Moor frog (Rana arvalis) in continental Europe as the best example. Males become UV-blue during breeding and create an amazing visual spectacle at ponds and marshes where they congregate. However, the reasons for this colour change have remained relatively unclear given that the vast majority of social interactions between amphibians are auditory (males sing during the breeding season to attract a high density of females in a small patch). Recent research indicates that while females remain brown during breeding the males change colour at that time not just in the human visible spectrum but also in UV spectrum but neither intensity nor wave length of this blue colour are correlated with body condition of the males. As such the most plausible explanation is that the colour change might serve to communicate male-male competitive advantages or potentially to showcase the fact that they are indeed males and therefore to avoid potentially energetically expensive mistakes when males try to get in amplexus with other males due to confusion in a small area, full of frogs.

Colour change in amphibians is a highly complex and variable topic, with numerous species-specific adaptations. So the question Why do amphibians change colour? has a myriad answers and can vary to involve different species, life stages, predation pressure, ambient conditions, especially temperature, stress, UV light and intra-sexual communication between males.

References:

King, R. B., Hauff, S., & Phillips, J. B. (1994). Physiological color change in the green treefrog: responses to background brightness and temperature. Copeia, 422-432.

Ries C., Spaethe J., Sztatecsny M., Strondl C & Hodl W.(2008) Turning blue and ultraviolet: sex-specific colour change during the mating season in the Balkan moor frog Journal of Zoology 276, 229–236

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Common Frog

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