Did you know that some birds living in cities have changed their songs so they can be heard above the roar of traffic? Most of us love hearing birds sing, but of course they don’t sing for our entertainment. They do so to mark their territories and to attract mates, so it’s a serious problem if they cannot hear each other.
And guess what? Researchers at the Centre of Ecological Research in Hungary have found that in order to be heard in noisy cities, some species of songbirds not only sing more loudly than they do in the wild, but they actually change the frequency of their songs, making them higher pitched. They also sing for longer and some even change notes. Clever birds. Something else I found interesting recently is that some scientists say that humans – who took millions of years to evolve – have now become the world’s greatest force for evolutionary change. Take elephant poaching for example. Humans have killed elephants on a massive scale for the illegal ivory trade. Poaching was particularly rife in the Gorongosa National Park during the Mozambican civil war. Researchers have now found that this intense poaching has actually changed the elephants’ evolution. Because poachers targeted elephants with tusks, those without tusks survived to breed – and so tuskless ellies in Gorongosa have now become dominant. Then there are lizards. The BBC reported last week that anole lizards in Puerto Rican cities have evolved longer legs with many more lamellae – microscopic hair-like thingies on their feet that enable them to stick to walls. In nature lizards walk mainly on rough surfaces, but in cities they often have to walk on super smooth surfaces like glass and metal – which can also become extremely hot. In response these lizards have evolved longer legs to keep their bodies further away from the hot surfaces and have grown more lamellae so they can walk on glass and metal. The article also described how some fish species have evolved to become smaller because of commercial fisheries targeting the big fish. This results in a larger number of smaller fish and they breed to produce smaller fish like themselves. But the wild animals that can adapt to humans changing the planet are the lucky ones, and they are in the minority. As we heat the planet, mainly with coal and oil emissions, we create more extreme weather – floods, droughts, fires – and most wildlife, animals and plants, cannot adapt to this rapid change. To be safe from the worst of global warming, we have to keep the average global temperature increase to 1.5°C. We have already reached 1.1°C. But there are hopeful signs: the sale of electric vehicles rose by 25% in 2025. Renewable energy, mainly solar and wind, overtook coal electricity production last year – an historic first. We need to keep our foot on the pedal of clean energy, for all the millions of animals and plants that cannot adapt to how humans are changing the planet. And as Nelson Mandela said, let’s hope world leaders make choices that reflect our hopes, not our fears.
