The Spiny Toad in Brittany
Between forests and ponds, the Spiny Toad leads a discreet life, shaped by the seasons and damp nights. From its migration to breeding sites to the emergence of tadpoles, discover the life cycle of this amphibian. Join me in Brittany as we set out to encounter this fascinating species.
A Nocturnal Encounter with the Spiny Toad in Brittany
It was in the Amazon that I learned to head out at night to observe amphibians. It is a different world that comes to life, and the sensations are completely different. The wind in the trees, a branch cracking, something plunging into the river… All our senses are alert and on the lookout, because our eyes can no longer fully do their job.
Living in Brittany, close to several wetlands and a valley crossed by the River Jaudy, it was only natural that I set out on my first nocturnal excursions to discover the amphibians living in my region.
I had missed an outing organised by a local association that runs wildlife observation activities, raises public awareness and protects sensitive natural areas where many species live side by side. That week, its members had gone out at dusk to look for salamanders and Spiny Toads. I decided to head out on my own, and during my very first outing, I did not have to wait long to find what I was looking for. Numerous toads were gathered along the edge of the pond, hopping around while the males called to attract females.
This animal, which we think we know so well, actually has a much more complex life cycle than it might seem… Why had so many suddenly appeared, when they seem almost nonexistent for most of the year?
We will answer that question in the following sections. But I can already tell you one thing: no, a toad is not a male frog! They are two different types of amphibians.
How to Recognise the Spiny Toad (Bufo spinosus)
How to Identify the Spiny Toad
It is time to take a closer look at this species. Why is it called the “Spiny” Toad? The name actually refers to the bumps on its back, which vary in shape and can sometimes be pointed. It also has large glands on the back of its head, known as parotoid glands. These are one of the features that help distinguish it from its close relative, the Common Toad (Bufo bufo), along with its generally larger size (females can reach up to 15 cm).
These glands secrete a substance that helps deter predators. It was only relatively recently, in 2004, that the Spiny Toad was recognised as a species distinct from the Common Toad (Bufo bufo).
It is a large, stocky toad with a broad head and a rounded snout. Its skin is usually brownish, but its colour can range from light beige to reddish-brown, and sometimes even greenish.
What particularly draws me to photographing this species, however, are its fiery-coloured eyes and horizontal pupils.
This species displays sexual dimorphism (physical differences between males and females). Males are smaller than females and have small nuptial pads on their fingertips, which allow them to grip the female’s back during mating.
What Is the Difference Between the Spiny Toad and the Common Toad?
The two species are very closely related. As we have seen, the Spiny Toad is generally larger and has more prominent parotoid glands.
Their geographical ranges can also help us tell them apart. If we divide France into three broad diagonal regions, the first, stretching from Brittany to south-eastern France, corresponds mainly to the Spiny Toad’s range. The central region is where the ranges of the two species overlap, while eastern France is mainly home to the Common Toad.
Where Does the Spiny Toad Live?
A Habitat Between Forest and Pond
Like most amphibians, it prefers cool, damp environments. It generally stays relatively close to the place where it was born: the pond where it developed. However, contrary to what one might expect, and like frogs, it is mainly terrestrial and only returns to bodies of water to breed.
The Spiny Toad can adapt to several types of habitat:
- Forests
- Farmland with hedgerows
- Gardens
- Hedges
- Areas offering natural shelter
- Urban parks, where it can also be found
Why Is the Spiny Toad So Rarely Seen?
Although it can be found in many different habitats, it is rarely seen. Firstly, it is mainly active at night and particularly favours cool, damp nights, like many other amphibians.
Secondly, this amphibian enters a period of winter dormancy between October and November and generally emerges towards the end of winter, between January and February. It then gradually resumes its activity and prepares to head towards its breeding site when weather conditions become favourable.
Finally, it spends much of its time sheltering under hedges, beneath layers of dead leaves or in rocky cavities. During winter dormancy, it may also burrow into the ground, sometimes reaching depths of up to 50 cm.
Furthermore, its slow movements and dark colouring make it particularly difficult to spot. Even during the breeding season, it can remain almost completely submerged in water. Only the top of its head emerges above the surface, allowing it to breathe. Sometimes, all you can see are its eyes.
What Does the Spiny Toad Eat?
The toad is an ambush predator. It spots its prey by detecting movement and catches it with its sticky tongue.
It is a gardener’s ally, thanks to its varied diet. It feeds on a range of creatures, including:
- Flies
- Ants
- Beetles
- Slugs
- Earthworms…
It can also feed on organic waste found in compost.
What Are Its Predators?
It has all kinds of natural enemies… That’s the law of nature!
Among birds, buzzards and herons are some of its predators. Certain mammals, such as the European badger, may also feed on it. Badgers can even turn the toad over to avoid its venom glands.
I also came across a surprising anecdote on the DORIS website (Common Toad species profile): hedgehogs may use toxic secretions from toads to coat their spines. This observation concerns the Common Toad, a close relative of the Spiny Toad. Quite an astonishing defensive strategy!
Finally, some grass snakes are also well-known predators of amphibians.
Destroying a pond or damaging a wetland therefore means depriving toads of an essential breeding site. But the consequences do not stop there: it can also deprive their predators of a food source and disrupt the balance of an entire ecosystem.
A Little Taxonomy
The word amphibios means “double life”. It refers to the difference between the aquatic environment of the larval stage and the terrestrial environment of adult life.
Behind this word lies a remarkable diversity of forms, lifestyles and adaptations. This is why amphibians are divided into three major groups:
- Anurans: meaning “without a tail”, this group includes frogs, toads and tree frogs, which lose their tails as they develop into adults. They may also have webbed feet and are, for the most part, good jumpers.
- Urodeles: these amphibians retain their tails into adulthood and include newts and salamanders (you can read my article dedicated to salamanders by clicking here).
- Gymnophionans (very little known): these are legless amphibians that look like worms. They are thought to be absent from Europe, so I won’t go into this group in greater detail for now.
Our toad therefore belongs to the Anuran group, which includes a variety of frogs and toads. Here are a few species found in Brittany:
- Spiny Toad (Bufo spinosus): the main subject of this article.
- Midwife Toad (Alytes obstetricans): a fascinating toad whose male carries the strings of eggs wrapped around his hind legs until they hatch.
- Natterjack Toad (Epidalea calamita): the only anuran that does not jump, because its legs are too short.
I would like to take this opportunity to remind you that ALL amphibians are protected in France. Their handling, capture and transportation are prohibited.
January and February Nights: The Migration to the Pond
The Breeding Season
At the end of winter (January–February), when temperatures begin to rise above 5°C, the Spiny Toad gradually becomes active again. This is the easiest time of year to observe it. Sometimes, all it takes is a cool, damp night to witness a real flurry of activity around the ponds.
When heading out at this time of year, you might think the cold would keep animals from venturing outside. Yet, as you approach a pond, you discover an abundance of life. The toads leave their shelters to make their way to their breeding sites, often returning to the same places they have used for several years.
The males arrive first. You can hear their calls, which help them attract females. The females arrive afterwards, and it is not unusual for some to have already found a mate along the way, with the male clinging to their backs.
Competition can be fierce and sometimes even fatal for females. To lay their eggs, they must reach the pond and remain in the water long enough. Sometimes, several males attempt to cling to the same female at once. In certain situations, this multiple amplexus can cause her to drown, as she is no longer able to reach the surface to breathe.
The Spiny Toad’s Migration: When the Road Gets in the Way
As with salamander breeding migrations, sometimes dozens or even hundreds of individuals move towards their breeding sites. These movements can lead to large concentrations of toads in certain areas.
Unfortunately, this journey sometimes involves crossing roads, and many animals lose their lives as a result.
To reduce this mortality, some conservation organisations organise rescue operations. Along roads where crossings are known to occur, temporary barriers are installed to prevent amphibians from crossing directly. Buckets are buried at regular intervals to collect the animals as they move along these barriers.
Volunteers regularly check the buckets, collect the toads that have fallen into them and help them cross the road safely. These operations also provide an opportunity to count the animals and gather information about the populations observed.
It is worth repeating: humans transform landscapes to meet their needs, but that does not mean wildlife species should have to disappear as a result.
The Spiny Toad’s Egg-Laying Underwater
When observing toads during the breeding season, you sometimes need to be patient to catch a glimpse of them. They often spot us from a distance and quickly dive underwater. Only after a few minutes might you see them discreetly return to the surface to breathe.
As I explained earlier, the male clings to the female’s back during amplexus. The female then lays the characteristic long strings of eggs. Unlike frog eggs, which are generally grouped together in gelatinous clumps, toad eggs are arranged in long, necklace-like strings.
A single string can contain several thousand eggs, sometimes as many as 6,000.
From Eggs to Tadpoles
The tadpoles, recognisable by their dark colouring, usually hatch after one to two weeks, depending on the water temperature and environmental conditions. They then undergo metamorphosis in early summer, generally in June or July.
I can assure you that egg strings and tadpoles look remarkably similar from one continent to another! I was able to observe these same stages of development in several amphibian species in the Peruvian Amazon. You can find these discoveries on my social media accounts.
At this stage of their development, tadpoles spend much of their time searching for food in the pond. Their diet consists mainly of plant matter, algae and organic debris. They can also be opportunistic, feeding on dead animals and even other tadpoles.
How Can We Protect Spiny Toads?
What Individuals Can Do
If you have a pond in your garden, it is probably home to many different species, provided its ecological balance is maintained (amphibians, insects, and so on).
It is important to protect these habitats. The idea that a pond inevitably attracts swarms of mosquitoes and quickly becomes a nuisance is simply not true. If insects such as odonates (dragonflies) come to lay their eggs there, or if amphibians breed in it, their larvae and tadpoles can help regulate mosquito populations. You may also attract birds that come to cool off or wash their feathers, and which will also help control certain insect populations.
Remember to provide stones or other features that allow small animals to climb out of the water easily if they accidentally fall in.
It may also be worth avoiding certain gardening or landscaping work during sensitive periods, particularly while amphibians are overwintering or breeding. Preserving hedgerows, piles of dead leaves and natural shelters also helps maintain the refuges they need to survive.
On the Roads
I believe conservation organisations are best placed to take action in this area. They know which sites are most vulnerable, have the necessary expertise and understand how to organise rescue operations.
But they cannot do it all by themselves! All organisations need volunteers to carry out their work. If you love nature, and amphibians in particular, don’t hesitate to get involved. These animals remain especially vulnerable to climate change and human activities.
I came across this article by Bretagne Vivante, which describes an amphibian protection initiative in Talensac, in the Ille-et-Vilaine department of Brittany.
Observing the Spiny Toad Without Disturbing It
Before sharing a few tips on how to go out and observe these animals, I would like to remind you once again that amphibians are legally protected in France. Depending on the species and circumstances, capturing, transporting or handling them is prohibited or strictly regulated. This may seem harmless, but handling an amphibian with bare hands can damage its delicate skin and transfer potentially harmful substances to it.
The best way to observe them while respecting their welfare is to join an outing organised by biologists or naturalist associations. You will have the opportunity to discover the Spiny Toad, learn more about its habits and make plenty of other discoveries along the way.
As we have seen, the best opportunities to observe it generally occur at night, in January and February, during the breeding season. However, be careful where you step so as not to crush animals moving along the ground.
You can also approach ponds to observe their activity, but take care not to trample or damage the surrounding vegetation. Many species hide there during the day, taking advantage of the cool conditions provided by grasses and plants, particularly newts.
FAQ
- Why is it called the “Spiny” Toad?
- The term “spiny” refers to the bumps on its back. These vary in shape and can sometimes be pointed, giving its skin a spiny appearance.
- What is the difference between the Spiny Toad and the Common Toad?
- The two species are very similar. The Spiny Toad is generally larger and has more prominent parotoid glands. Their geographical ranges also help distinguish them: the Spiny Toad is mainly found in western and south-western France, while the Common Toad is found notably in the north-east. However, their ranges overlap in some areas.
- Why are so many toads found in the same place?
- In January and February, toads make their way to their breeding sites. Many individuals then travel towards the ponds they regularly use for breeding. It is not unusual to see dozens, or even hundreds, gathered in the same place during this period.
- Is the Spiny Toad poisonous?
- The Spiny Toad has parotoid glands that secrete toxic substances to protect it from predators. It does not have a system for injecting venom, unlike some venomous animals. However, contact with its secretions can cause irritation, particularly to the eyes and mucous membranes. It is therefore best not to handle it. It is also worth remembering that amphibians are legally protected in France: capturing or handling them, and damaging their habitats, is prohibited or regulated depending on the species and circumstances.
- Is finding a toad in your garden a good sign?
- Yes! The presence of amphibians in a garden can indicate that the habitat is favourable to biodiversity, with suitable shelters and sufficient moisture. The Spiny Toad can also be a useful ally for gardeners. Its diet includes slugs, insects and other small invertebrates that may damage your vegetable plants. All the more reason to make room for it in your garden!