Birds colliding with windows are an upsetting symptom of human encroachment on nature. But the barriers we put up between ourselves and the natural world are part of a larger problem.
It’s a depressingly common sight. A bird, lying on the ground, having crashed into glass it cannot see. Windows, and their impact on birds, are something we notice in our everyday lives – and they are a fitting symptom of humanity’s encroachment on nature. But they are not one of the top threats to birds. While less visible, human development has caused many greater problems we should all be aware of, because without this awareness, we can’t combat these threats.
One of the biggest ways humans are negatively impacting nature is through habitat loss. Our recent study State of the World’s Birds 2018 showed that one in eight birds is now threatened with extinction, and the number one threat is something that rapidly eats up natural habitats: agriculture. Farmland now takes up more than a third of the earth’s land surface, and impacts 74% of globally threatened birds.
Worryingly, even birds once considered widespread and common have started to see dramatic population plummets. The European Turtle-dove Streptopelia turtur was once a familiar migrant to Europe, Central Asia and the Middle East from the Sahel zone of Africa. But thanks in a big part to habitat loss, the species is now declining across its range, especially in Western Europe, and it has recently been classed as Vulnerable to extinction.
However, the trouble with farming isn’t just that it destroys natural habitats. Many bird species, such as the Northern Lapwing Vanellus vanellus, have been happily thriving on farmland for centuries. A big problem is intensification: using pesticides and artificial fertilisers to grow vast, otherwise barren monocultures of a single crop. A recent study from the USA found that migrating White-crowned Sparrows Zonotrichia leucophrysexposed to a class of pesticide known as neonicotinoids lost a quarter of their body mass and fat stores.
Since nearly two-thirds of species are found in forests, it’s no surprise that logging is the second biggest threat to birds. Many of these species cannot live outside of forests, and are unable to fly between remaining fragments.
In Bolivia, for example, the Blue-throated Macaw Ara glaucogularis, once threatened by the illegal pet trade, is now being chased out of its home by ranchers burning forest to make room for cattle grazing. In Madagascar, deforestation caused by slash-and-burn practices to make way for subsistence farming is threatening the Madagascar Red OwlTyto soumagnei, which is now Vulnerable to extinction.
In fact, in parts of South East Asia, there is now so little pristine forest left that many forests will be logged for a second or third time in the near future.
And this is causing a worrying new trend in bird extinctions. Over the past centuries, the vast majority of bird extinctions have occurred on islands – typically due to overhunting or the threat of invasive species. However, there is now a growing wave of extinctions sweeping across the continents, driven mainly by habitat loss. In fact, in 2000, the number of extinctions on continents overtook those on islands for the first time.
We’re working hard to overturn this trend. Across the world, we’re helping farmers to welcome wildlife back onto their land and farm in a way that can continue to support livelihoods long into the future. We’re also part of the ambitious Trillion Treescollaboration, which aims to plant, protect and restore a trillion trees by 2050.
But a task of arguably equal importance is to change people’s perceptions of the crucial role they play in nature. So while we want to stop birds from crashing into windows, the bigger challenge is to make sure the windows aren’t there in the first place.