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Some raptors adapt well to growing cities, but others are struggling

As the relentless pace of urbanization threatens biodiversity, Australian native wildlife struggles for survival. Raptors are among the most affected, with their habitat shrunk, overshadowed by towering buildings, and constantly disturbed by car noises and night lights.

In an attempt to understand the “urban tolerance” of Australian raptors, a team of experts led by the BirdLab at Flinders University and the University of Vienna conducted an exhaustive study of 24 species. 

What the researchers learned 

The findings reveal an interesting disparity: smaller birds of prey, such as kites and falcons, display a higher tolerance for living in urban areas than larger species.

The researchers found that the Eastern Barn Owl, Brahminy Kite, and the Australian Hobby (Falco longipennis) have demonstrated the highest tolerance to urbanization. 

On the other hand, the Brown Falcon (Falco berigora) and the Wedge-tailed Eagle (Aquila audax) have been identified as the least tolerant raptor species to urban areas.

The experts also discovered that urban tolerance among wildlife is generally higher in species that have adaptable behavior, high fertility rates, and a strong ability to disperse across diverse landscapes like urban green spaces, parks, cemeteries, or golf courses. 

Dr. Petra Sumasgutner, a raptor conservation researcher at the University of Vienna, and lead author of the study, highlighted the importance of community science data in this research. Using data from eBird, the team analyzed raptors’ body mass, nest and habitat types, feeding habits, and migratory status to evaluate their urban tolerance.

Raptor populations are declining worldwide

“The worldwide decline in predator populations is contributing substantially to the biodiversity crisis,” said Dr. Sumasgutner. “As we see extensive cascading effects on ecosystems caused by human-dominated landscapes, we can find examples of predators which stay or return to ecosystems, creating a buffer against biological invasion and disease transmission.”

In light of the concerning population decline, especially in larger raptors around the world, it is worth noting that out of the over 500 raptor species, 52% are on the decline and 19% are on the brink of extinction.

These findings were inspired by the studies of Taylor Headland, a PhD student at Flinders University, who shed light on the adaptive techniques of the small-bodied Australian falcon – the Nankeen kestrel – in both human-modified and natural landscapes.

“As raptors are vital for ecosystem functioning, prioritizing feeding and breeding habitat for urban-tolerated raptor species is essential to enable biodiverse urban landscapes,” said Headland. “We are concerned for the raptors of Australia and the Southern Hemisphere which are far less studied than those in the Northern Hemisphere, making resources like eBird life invaluable.”

Raptor sightings

In a dataset comprising 276,674 species observations of 24 raptors, the Whistling Kite (Haliastur sphenurus) emerged as the most frequently detected raptor with 45,787 observations, while the Eastern Barn Owl (Tyto alba) was observed the least.

Additionally, the study found that the Brown Goshawk (Accipiter fasciatus) and Southern Boobook (Ninox boobook) were most commonly observed in Docklands Park, a central area of Melbourne. 

The Whistling Kite was frequently sighted at Lagoon Island, Lake Argyle, a region in north-eastern Western Australia with the lowest median radiance.

Importance of citizen science 

Since its inception over a decade ago by the Cornell Lab of Ornithology and US Audubon Society, eBird has collected more than 90 million checklists and 1.2 billion observations of birds, making it one of the most successful community or citizen science projects to date.

While the study underscores the dire state of raptor species and their struggle for survival amidst expanding urbanisation, it also points to an urgent need for balanced conservation efforts that consider the needs of both smaller, adaptable raptors and larger species less tolerant to urban expansion.

More about raptors 

Raptors, also known as birds of prey, are a group of avian species characterized by their predatory lifestyle. These birds are known for their exceptional hunting skills, sharp talons, and beaks adapted for tearing flesh. Raptors can be found across the globe in nearly every type of environment, from the highest mountains to coastal areas and deserts to urban landscapes.

Raptors include various species of eagles, hawks, falcons, owls, vultures, ospreys, and kites. Each species has its own unique set of traits and adaptations. For example, eagles are generally known for their size and power, with some species capable of taking down large prey such as deer. Hawks, meanwhile, are renowned for their speed and agility, which they use to snatch up smaller prey mid-flight.

Falcons, such as the peregrine falcon, are recognized as the fastest animals on the planet, reaching speeds of over 240 miles per hour during their hunting stoop (high-speed dive). Owls are known for their remarkable nocturnal hunting abilities, made possible by their silent flight and keen night vision.

Raptors play a critical role in the ecosystem by controlling the populations of other animals, particularly rodents and other small mammals. They are at the top of the food chain, and changes in raptor populations can often signal changes in the health of the entire ecosystem.

However, raptors face numerous challenges, including habitat loss, pesticide exposure, and climate change. Many species are declining and some are threatened with extinction. Efforts are being made worldwide to conserve these magnificent birds, including habitat preservation, captive breeding and release programs, and public education about the crucial role raptors play in our world.

The research is published in the journal Scientific Reports.


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