Urbanization is a threat to 78% of the world’s bird species

We all know that humans have a significant impact on the planet. We build cities, roads, and farms that radically change landscapes. But just how much of a strain is urbanization placing on our feathered friends – the birds?

A new study from the University of Helsinki paints a worrisome picture. Turns out, most birds don’t like living anywhere near us, and their populations are suffering because of it.

Urbanization doesn’t look good for many birds

Scientists recently investigated how well birds handle living in human-dominated environments. Sadly, the news is a downer: 78% of the world’s bird species simply can’t cope. What’s more, these same species are the ones with declining populations.

“Threatened species, and species with declining populations, are less tolerant to breeding in human-dominated habitats,” says Emma-Liina Marjakangas, the lead researcher in the study.

Sadly, a whopping 14% of the world’s 11,000 bird species are currently on the brink of extinction. These alarming numbers show that our actions are having real consequences for the world’s birds.

Challenges faced by birds on urbanization

Adapting to urbanization presents a complex challenge for birds. Unlike some creatures that may find urban spaces easier to navigate, birds encounter specific obstacles. These range from the loss of natural habitats to the introduction of pollution and noise.

Each alteration we make can disrupt their feeding, breeding, and migratory patterns. Essentially, urbanization creates environments that many bird species struggle to adapt to, leading to a decline in their populations.

Mammals can sometimes adapt their shelter-seeking and foraging behaviors to changing environments. However, birds depend greatly on certain environmental features for their existence and reproduction. These features include specific types of vegetation, water sources, and nesting sites. Without these, birds struggle to survive and breed successfully.

Take the fernwren, a bird from Australia’s tropical forests. Marjakangas points out: “[It] is endangered, has a declining population and a very low tolerance to any human pressure.” The fernwren needs the quiet and seclusion of a rainforest to thrive.

For many bird species, particularly those that have evolved in pristine wilderness areas, even minimal human presence can disrupt their delicate way of life. Here’s a closer look at some of the key challenges birds face in our world:

Habitat loss and fragmentation

When we build cities, roads, and farms, we not only destroy natural habitats but also fragment them. This means that large areas of suitable habitat are broken up into smaller, isolated patches. These fragmented habitats often lack the resources birds need, such as nesting sites, food sources, and safe corridors for movement.

Increased noise levels

The constant noise pollution due to urbanization can be a major stressor for birds. It can interfere with their communication, making it difficult for them to attract mates, defend territories, and warn each other of predators.

Light pollution

Artificial light at night disrupts the natural light cycle that birds rely on for a variety of functions, including navigation, breeding, and foraging. For instance, some migratory birds navigate using the stars, and artificial lights can confuse them. Additionally, extended periods of light can shorten a bird’s day, potentially leading to issues with hormone regulation and reproduction.

Predators

Unfortunately, human settlements often attract predators that birds wouldn’t encounter in undisturbed areas. Domestic cats are a major threat to ground-nesting birds, and some birds may struggle to adapt to the presence of opportunistic scavengers like rats or raccoons.

Reduced food availability

Human activities often lead to changes in plant communities. This can mean a decline in the types of plants and insects that birds rely on for food. Additionally, the use of pesticides and herbicides can directly harm bird populations or reduce the insect prey they depend on.

Competition for resources

Birds in human-dominated environments often face increased competition for limited resources, such as food and nest sites. This competition can come from other bird species that have adapted well to human environments, as well as from invasive species that humans may have unintentionally introduced.

These are just some of the challenges that birds face in our world. By understanding the specific ways that human activities impact birds, we can develop more targeted conservation strategies to help them survive and thrive.

Some birds are more adaptable

Not all birds are created alike, and some are surprisingly adaptable. Just like any other living organism, birds exhibit a remarkable range of adaptations that allow them to survive in diverse environments.

This means that some bird species possess unique characteristics that have enabled them to not only tolerate human presence but even thrive in our modified landscapes.

Interestingly, the study found that Europe and North America had more bird species that could at least handle some human presence. The researchers theorize that centuries of dramatic landscape change may have already driven away the most sensitive bird species in these regions. It’s a sobering thought – what else might we have lost without even knowing?

“Some species can tolerate even the most intense human pressures on all continents. Common Swifts are an example of such species that can be found breeding in urban areas all around the world,” explains Marjakangas. These adaptable birds prove that some species can learn to navigate the challenges of living near humans.

Protecting birds from urbanization

Sure, setting aside large chunks of untouched land for nature is vital. But as this study shows, it won’t help all our feathered friends. We need to go beyond national parks and think more broadly about how we can share the planet with a diverse range of bird species. This means:

• Restoring damaged ecosystems: Bringing back native plants and creating healthier habitats, even in smaller patches, can be a lifeline for struggling bird species.
• Bird-friendly design: Our cities don’t have to be completely hostile to birds. Things like bird-safe windows, reducing harsh lighting, and patches of native vegetation can make a difference.

“This study enables us to identify species that are particularly sensitive to human activity and need more protected habitats to thrive,” explains senior curator Aleksi Lehikoinen from the Finnish Museum of Natural History.

The next time you hear birdsong, remember – many of those little musicians are struggling with the changes we make to our world.

This study is a reminder that conservation isn’t just about far-off rainforests. It’s about how we design our own backyards, towns, and cities, and whether we can leave space for the remarkable diversity of birds to thrive alongside us.

The study is published in the journal Global Ecology and Biogeography.

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