Författare: Becky Thomas Senior Lecturer in Ecology Royal Holloway Unive

During February and March, volunteers head out after dark with buckets and florescent jackets to stand on roads across the UK. These are the toad patrols, and they help an amphibian with love on its mind.

Early spring is the start of the breeding season for common toads (Bufo bufo to scientists). A warm, wet evening is the perfect cue for males to embark for a pond where they hope to find a mate. Females usually arrive a few weeks later, but they only stay long enough to mate and spawn.

Males, who outnumber the females, must engage in gladiator-style battles to win mates. In one pond scientists studied in Sweden, there were four males for every female. The scientists reported intense competition, with only 20.5% of males breeding successfully. The male grabs hold of the female for several days, and as the female begins laying eggs, he fertilises them. Toads lay a long double string of eggs that are black in colour, unlike the mass of eggs laid by frogs.

After that, the parents begin to depart the pond. The spawn they leave behind takes around 16 weeks to grow into toadlets. You’ll often find the toadlets leaving a pond en masse during a wet summer evening, darting for cover to avoid getting eaten. Outside of the breeding season, toads spend their time in woods, grassland and gardens until spring begins and they start their migration.

Stubbier than frogs, with shorter legs, toads crawl to breeding ponds, which can be up to 5km away. Their destination is typically a familiar one. One study found that over 80% of adults that survived to breed the following year returned to their pond of origin.

You may wonder why a species that has made this migration for millions of years needs the help of a toad patrol. Toads are equipped for the journey to their breeding ponds, but they are not built to withstand the obstacles and barriers that people have put in their way. The natural world has been split apart by roads. Britain has 247,800 miles of road, on which 20 tonnes of toad is estimated to be squashed each year.

A toad patrol on duty near Winchester in southern England.
Chris Ison/PA Images/Alamy Stock Photo

What toad patrols have taught us

If a road has lots of toads crossing in the spring, it can be registered with Froglife and a patrol set up to ferry toads across it. The charity Froglife is committed to the conservation of all amphibians, reptiles and their habitats, and has coordinated toad patrols for over 35 years.

Toad patrollers are tasked with recording how many amphibians they help across the road in an evening and how many they find dead. Volunteers are also asked to record the number of days in which a patrol is active each season and how many people take part. This helps scientists understand whether any changes in recorded toad numbers are not just a result of more people submitting data. In 2023, there were 203 crossing sites in the UK, which helped over 115,000 toads to cross a road safely.

Drive carefully.
DP Wildlife Vertebrates/Alamy Stock Photo

The information gathered by these patrols has shown that toad numbers have declined by 68% since 1985 in some areas of the UK, but the reasons are unclear. The loss of ponds for breeding and disruption to migration routes are among the most likely causes.

Roughly half of the UK’s ponds were lost during the 20th century. Those that remain are in a generally poor state. It is no surprise that toads have continued to decline despite the best efforts of volunteers, who have been venturing out on dark, damp evenings since the early 1980s.

One study analysed how effective the patrols were for conserving toads. The authors mentioned a period in Cambridgeshire in the mid-1990s, when volunteers dwindled each year because of declining toad numbers at crossings.

This period still saw significant toad casualties, and it took several years before people realised that toad populations could be reduced by road traffic. By this point, local ponds, despite being protected, saw only small numbers of toads breeding and hardly any toads at the crossing because the local population was so depleted.

Scientists are better informed of the threat roads pose to toad populations.
Allan Staley/Alamy Live News

Mr Toad from Wind in the Willows may have enjoyed zooming around in his sports car, but reckless driving on rural roads is causing real toads to decline. With ever smaller populations, toads need all the help they can get to ensure that adults arrive at their breeding ponds safely.

The Toads on Roads project is one way you can help support toads. See if there is one near you.

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Cities can be deeply unwelcoming places for wildlife. They are noisy, difficult to get around, full of people and heavily reliant on artificial lighting. Yet some species do better in urban areas than in rural ones.

Research is showing that animals of the same species that live in cities and the countryside are behaving differently. These disparities will probably grow since
over half of people worldwide now live in urban areas, and cities and towns are getting bigger.

A recent study from Tel Aviv University found that Egyptian fruit bats living in urban parts of Israel gave birth two and a half weeks earlier than rural populations. This gives them an advantage as they are more likely to reproduce twice per year.

In the urban areas in the study there was a higher abundance and diversity of fruit trees. In Tel Aviv, for instance, the trees are watered. This means there is fruit for a longer period across the year, meaning more reliable food supplies for the bats.

They may also be benefiting from the urban heat island effect, with warmer temperatures reducing the harshness of the winters felt by their rural neighbours.

Most species perceive humans as predators, so our presence disturbs and distracts them from feeding and breeding. To survive in human-dominated cities, animals must therefore be bold.

This is something researchers have studied for a while in wildlife like foxes. Urban foxes are often more confident in their response to new food when it is presented in a novel object like a puzzle box.

City foxes tend to be bolder.
johnhardingfilm/Shutterstock

Urban birds, from robins to feral pigeons, are also bolder. In a 2008 study scientists found that urban birds are more tolerant of human disturbance than rural ones), allowing humans to approach them closely.

The birds that reacted less to approaching humans were descended from a large number of generations since urbanisation, showing a long history of adaptation. This behavioural change helps these animals to adjust their stress responses when they are exposed to new situations. If they did not do this, they would suffer with chronic stress.

To test whether this boldness in birds is due to evolutionary adaptations, one 2006 experimental study in Germany hand-raised blackbird chicks taken from both an urban centre and a nearby forest.

They kept all the birds in the same environment until they were adults and then tested their acute stress responses when the birds were caught and handled. The birds from the city had a lower stress response, suggesting that this difference was genetically determined.

However, urban birds tend to be less successful in raising chicks than those in more natural areas. Although birds can take advantage of food provided by people in many cities and towns across the world – whether directly in bird feeders, or by scavenging on our discarded food – urban areas do not provide enough of the invertebrate prey that many nestlings need.

One study published in 2020 found that the biggest challenge for urban great tits was the low abundance of nearby insects.

Urban great tits have their own problems.
Zestocker/Shutterstock

Same species, different city

Many of these changes in urban species are difficult for people to detect, but one in particular becomes clear when you spend time in cities across the world. Have you noticed that whichever city you visit there seem to be many animals of the same species?

Scientists call this biotic homogenisation. It happens when places start to become increasingly similar over time with the species that you can find there.

This process begins with the exodus of species that cannot tolerate living alongside humans. Large mammals, often predators, are the first to go as an area becomes increasingly urbanised.

Then the non-native species begin to move in. Feral pigeons, rats, starlings and many other species are introduced by people over time, whether accidentally or deliberately, until a point is reached when the biodiversity found in one city, say in the US, starts to resemble another in Europe.

These species often have broader dietary and habitat niches, which makes them good at exploiting urban areas.

Noticed how the wildlife in cities is pretty similar wherever you go?
PauliusPeleckis/Shutterstock

Urbanisation is continually changing our relationship with animals and how we perceive nature. Although scientists debate whether we have entered the Anthropocene (a new geological age based on significant planetary changes caused by humans) it is undeniable that humans have and still are moulding landscapes to suit our needs.

The growth of cities and other urban areas is set to continue, with future urban expansion predicted to swallow 11-33 million hectares of natural habitat by 2100, an area the size of Norway. Indeed, humans are becoming the largest driving force in the evolution of wildlife. Läs mer…